**Neural Tube Defects in Algeria**

Bakhouche Houcher1, Samia Begag1, Yonca Egin2 and Nejat Akar2

*1Faculty of Sciences, Department of Biology University of Sétif, Sétif 2Department of Pediatric Molecular Genetics, University Medical School, Ankara, 1Algeria 2Turkey* 

#### **1. Introduction**

162 Neural Tube Defects – Role of Folate, Prevention Strategies and Genetics

[117] Kibar Z, Salem S, Bosoi CM, Pauwels E, De Marco P, Merello E, Bassuk AG, Capra V,

[118] Lei YP, Zhang T, Li H, Wu BL, Jin L, Wang HY. 2010. VANGL2 mutations in human

cranial neural-tube defects N Engl J Med 362:2232-2235.

Clin Genet 2011 80(1):76-82.

Gros P. 2010. Contribution of VANGL2 mutations to isolated neural tube defects.

Neural tube defects (NTD) are severe congenital malformations and can be fatal. These malformations constitute one of the principal causes of mortality and morbidity in childhood. Classically, NTD have been divided into two main groups: (a) defects affecting cranial structures, such as anencephaly and encephalocele, and (b) defects involving spinal structures (spina bifida) (Verrotti et al., 2006). In newer classification schemes for the NTD, encephalocele shows more similarities to spina bifida or anencephaly than it shows differences with respect to characteristics, temporal trend and the impact of fortification (Rowland et al., 2006).

In recent years, various clinical and experimental studies have demonstrated that folic acid supplementation during the periconceptional period can prevent the occurrence and recurrence of NTD (Czeizel and Dudas, 1992). Thus, a low folate status is associated with an increased NTD risk. Up to 70% of human NTD can be prevented by folate supplementation during the periconceptional period (Czeizel and Dudas, 1992; MRC Vitamin Study Research Group, 1991).

Both genetic and environmental factors such as the maternal vitamin status have been proposed to affect the risk for NTD (Copp et al., 1990). The incidence is nearly 1 in 1,000 births, but various numbers have been reported from different countries (Botto, 2000). At present, the exact mechanism through which folic acid works remains unknown (Morrison et al., 1998). It is known that folic acid plays an important role in the homocysteine metabolism, in which 5-methylene-tetrahydrofolate (THF), formed upon reduction of 5,10 methyl-THF by the enzyme methylene-THF reductase (MTHFR), donates its methyl group via the vitamin- B12-dependent enzyme methionine synthase to homocysteine to form methionine. Another major pathway of homocysteine metabolism is the transsulfuration pathway, in which homocysteine is irreversibly condensed with serine to cystathionine by the vitamin B6-dependent enzyme cystathionine -synthase (Afman et al., 2003).

The genetic risk factors for NTDs have been intensively studied in recent years. As a result, numerous candidate genes associated with folate metabolism have been studied in detail and their association with NTD, including MTHFR (Selhub et al., 1993). The prevalence of

Neural Tube Defects in Algeria 165

purity were quantified for each DNA sample by spectrophotometry (Nanodrop ND-1000).

The genetic analysis of the MTHFR C677T polymorphism was performed by real-time polymerase chain reaction (PCR) via a melting curve analysis performed on a Light Cycler (Roche Molecular Biochemicals, Mannheim, Germany) in borosilicate capillaries with an MTHFR C677T polymorphism detection kit (Roche Molecular Biochemicals). Primers and fluorescence-labelled hybridization probes designed were used. The primer sequences were: 5'-TGGCAGGTTACCCCAAAGG-3' (forward) and 5'-TGATGCCCATGTCGGTGC-3'

5'-TGAGGCTGACCTGAAGCACTTGAAGCACTTGAAGGAGAAGGTGTCT-3'-Flu and 5'-

The 20.0 μl amplification reaction was prepared, containing 5.0 μl genomic DNA, 1.6 µl Mg, 4.0 µl Reagent Mix (Specific primers and probe, Tib molbion), 2 µl Fast Start DNA master

Cycling conditions for MTHFR were initial denaturation at 95°C for 10 min, followed by 45 cycles with denaturation at 95°C for 5 s, annealing at 60°C for 10 s and extension at 72°C for 15 s. After amplification, melting curves have been generated following denaturation of the reaction at 95°C for 20s, holding the sample at 40°C for 20s and then slowly heating the sample to 85°C with a ramp rate of 0.2°C/s and simultaneous monitoring of fluorescence

The identification of the *MTHFR* genotype has been performed by an analysis of the melting peaks of the run of the real-time PCR. The presence of just 1 melting peak at 63.0°C indicates a wild–type genotype, 2 melting peaks at 54.5°C and 63.0°C indicate a heterozygous mutant,

Fig. 1. Melting-curve analysis was performed analyze the MTHFR C677T polymorphism

Comparisons of NTD between sex and/or between mother's age and of genotype and allele frequencies between cases and control subjects were done by a 2 test. Allele frequencies were deduced from genotype distribution Statistical significance was accepted at p < 0.05. The odds

LC-640-CGG GAG CCG ATT TCA TCA T-3'-PHO (TIB Molbiol, Berlin Germany).

HybProbe (Roche Diagnostics Mannheim, Germany), 7.4 μl H2O (PCR-grade).

and 1 melting peak at 54.5°C indicates a homozygous mutant (fig. 1).

**2.3 Polymorphism analysis by LightCycler PCR and melting curve analysis** 

DNA samples were stored at -4°C until use.

(reverse) and hybridization probe sequences were:

decline.

**2.4 Statistical analysis** 

MTHFR C677T genotypes varies among different ethnic groups. It is low in Africa, whereas in Europe and North America it ranges between 5% and 15%, thereby suggesting regional differences in the MTHFR C677T distribution (Almawi et al., 2004). For example, a high prevalence of the TT genotype was reported for Mexico (34.8%) (Mutchinick et al., 1999), Italy (21.4%) (D'Angelo et al., 2000) and France (16.8%), while lower prevalences were reported for Thailand (1.4%) and India (2.0%).

There are several studies that have found a positive association between NTD and the common mutation C677T of MTHFR, and other studies that have not found such an association. Van der Put et al. (1995) discovered that a common genetic defect in the *MTHFR* gene, the C677T mutation, resulting in a reduced but not an abolished enzyme activity, is a genetic risk factor for spina bifida. The C677T mutation is associated with a 2- to 4-fold increased risk if an NTD mother is homozygous for this mutation.

Data from several association studies on different ethnic groups have resulted in conflicting conclusions about the role of the C677T mutation of the MTHFR gene, as a risk factor for NTD (Rampersaud et al., 2003).

In the present study, we aimed to determine the prevalence of the MTHFR C677T polymorphism in the Algerian population and evaluated their impact on NTD individuals and their relatives.

#### **2. Patients and methods**

#### **2.1 Study population**

The study was a retrospective review of the medical case notes over a 3-year period. Infants born with a NTD were identified from the University Maternity Hospital of Sétif (Algeria) database. The following items are routinely collected for each case: birth date, sex, single or multiple birth, presence of additional congenital malformations, mother's county of residence and birth date. The proportion of all congenital anomalies on the register accounted for by NTD was calculated. Prevalence (birth) rates per 1,000 births were examined each year for 3 year study period. The following factors were compared by type of NTD: prevalence, sex ratio, mother's age and season of birth. It was not possible to identify stillbirths with NTD born at home and we have no data on prenatal diagnosis of NTD by ultrasound among our patients.

#### **2.2 Sample collection and DNA extraction**

The total study group consisted of 71 mothers and 27 fathers. A group of 147 apparently healthy adult (82 women and 65 men) were used as control group. Peripheral blood samples were collected by venipuncture, collected in test tubes which contained EDTA as an anticoagulant and maintained frozen at -20°C until extraction of DNA and genotyping. The research protocol was approved by the Sétif Medical Faculty Ethics Committee.

DNA extraction was performed using the conventional phenol-chloroform method. After haemolysis of the blood in hypotonic solution, the DNA was isolated by using a simple proteinase K treatment at 65°C in the presence of SDS, followed by ammonium actetate precipitation of debris and ethanol precipitation of the DNA. Then, DNA amount and DNA

MTHFR C677T genotypes varies among different ethnic groups. It is low in Africa, whereas in Europe and North America it ranges between 5% and 15%, thereby suggesting regional differences in the MTHFR C677T distribution (Almawi et al., 2004). For example, a high prevalence of the TT genotype was reported for Mexico (34.8%) (Mutchinick et al., 1999), Italy (21.4%) (D'Angelo et al., 2000) and France (16.8%), while lower prevalences were

There are several studies that have found a positive association between NTD and the common mutation C677T of MTHFR, and other studies that have not found such an association. Van der Put et al. (1995) discovered that a common genetic defect in the *MTHFR* gene, the C677T mutation, resulting in a reduced but not an abolished enzyme activity, is a genetic risk factor for spina bifida. The C677T mutation is associated with a 2- to 4-fold

Data from several association studies on different ethnic groups have resulted in conflicting conclusions about the role of the C677T mutation of the MTHFR gene, as a risk factor for

In the present study, we aimed to determine the prevalence of the MTHFR C677T polymorphism in the Algerian population and evaluated their impact on NTD individuals

The study was a retrospective review of the medical case notes over a 3-year period. Infants born with a NTD were identified from the University Maternity Hospital of Sétif (Algeria) database. The following items are routinely collected for each case: birth date, sex, single or multiple birth, presence of additional congenital malformations, mother's county of residence and birth date. The proportion of all congenital anomalies on the register accounted for by NTD was calculated. Prevalence (birth) rates per 1,000 births were examined each year for 3 year study period. The following factors were compared by type of NTD: prevalence, sex ratio, mother's age and season of birth. It was not possible to identify stillbirths with NTD born at home and we have no data on prenatal diagnosis of NTD by

The total study group consisted of 71 mothers and 27 fathers. A group of 147 apparently healthy adult (82 women and 65 men) were used as control group. Peripheral blood samples were collected by venipuncture, collected in test tubes which contained EDTA as an anticoagulant and maintained frozen at -20°C until extraction of DNA and genotyping. The

DNA extraction was performed using the conventional phenol-chloroform method. After haemolysis of the blood in hypotonic solution, the DNA was isolated by using a simple proteinase K treatment at 65°C in the presence of SDS, followed by ammonium actetate precipitation of debris and ethanol precipitation of the DNA. Then, DNA amount and DNA

research protocol was approved by the Sétif Medical Faculty Ethics Committee.

reported for Thailand (1.4%) and India (2.0%).

NTD (Rampersaud et al., 2003).

**2. Patients and methods** 

ultrasound among our patients.

**2.2 Sample collection and DNA extraction** 

and their relatives.

**2.1 Study population** 

increased risk if an NTD mother is homozygous for this mutation.

purity were quantified for each DNA sample by spectrophotometry (Nanodrop ND-1000). DNA samples were stored at -4°C until use.

#### **2.3 Polymorphism analysis by LightCycler PCR and melting curve analysis**

The genetic analysis of the MTHFR C677T polymorphism was performed by real-time polymerase chain reaction (PCR) via a melting curve analysis performed on a Light Cycler (Roche Molecular Biochemicals, Mannheim, Germany) in borosilicate capillaries with an MTHFR C677T polymorphism detection kit (Roche Molecular Biochemicals). Primers and fluorescence-labelled hybridization probes designed were used. The primer sequences were: 5'-TGGCAGGTTACCCCAAAGG-3' (forward) and 5'-TGATGCCCATGTCGGTGC-3' (reverse) and hybridization probe sequences were:

 5'-TGAGGCTGACCTGAAGCACTTGAAGCACTTGAAGGAGAAGGTGTCT-3'-Flu and 5'- LC-640-CGG GAG CCG ATT TCA TCA T-3'-PHO (TIB Molbiol, Berlin Germany).

The 20.0 μl amplification reaction was prepared, containing 5.0 μl genomic DNA, 1.6 µl Mg, 4.0 µl Reagent Mix (Specific primers and probe, Tib molbion), 2 µl Fast Start DNA master HybProbe (Roche Diagnostics Mannheim, Germany), 7.4 μl H2O (PCR-grade).

Cycling conditions for MTHFR were initial denaturation at 95°C for 10 min, followed by 45 cycles with denaturation at 95°C for 5 s, annealing at 60°C for 10 s and extension at 72°C for 15 s. After amplification, melting curves have been generated following denaturation of the reaction at 95°C for 20s, holding the sample at 40°C for 20s and then slowly heating the sample to 85°C with a ramp rate of 0.2°C/s and simultaneous monitoring of fluorescence decline.

The identification of the *MTHFR* genotype has been performed by an analysis of the melting peaks of the run of the real-time PCR. The presence of just 1 melting peak at 63.0°C indicates a wild–type genotype, 2 melting peaks at 54.5°C and 63.0°C indicate a heterozygous mutant, and 1 melting peak at 54.5°C indicates a homozygous mutant (fig. 1).

Fig. 1. Melting-curve analysis was performed analyze the MTHFR C677T polymorphism

#### **2.4 Statistical analysis**

Comparisons of NTD between sex and/or between mother's age and of genotype and allele frequencies between cases and control subjects were done by a 2 test. Allele frequencies were deduced from genotype distribution Statistical significance was accepted at p < 0.05. The odds

Neural Tube Defects in Algeria 167

The observed frequencies of the various genotypes and alleles of C677T polymorphisms in the *MTHFR* gene are shown in Table 2. Forty-two (46%) out of 92 mothers analysed for the C677T polymorphism carried the T allele and 15 (16%) were homozygotes (table 2). Finally, 5 (10%) out of 48 fathers had the TT genotype and 22 (46%) were heterozygotes (Tab. 2). In the control mothers group (n = 82), 35 (43%) were heterozygotes (table 3). In the control mothers group (n = 82), 35 (43%) were heterozygotes and 14 (17%) were homozygotes (table 2). These frequencies were not significantly different from those observed in a sample of the

There was no statistically significant difference between the genotype and allele frequencies of C677T polymorphisms in mothers with a previous child with NTD compared with mother controls. The allele frequencies for the MTHFR C677T polymorphism were similar in case mothers and control mothers, with approximate allele frequencies of 0.6 and 0.3 for C and T alleles, respectively (table 2). Comparisons of genotype frequencies between case mothers and controls did not reveal any statistically significant differences (tables 2, 3).

The frequency of C677T homozygotes in the couple was higher in mothers with a previous child with NTD than in corresponding controls (19 vs. 14%), but the difference was not statistically significant. The OR was 2.05 (95% CI: 0.78-5.41) (table 2). The frequency of T alleles too was higher in case mothers compared to controls (45 vs. 34%; OR = 1.55; 95% CI:

> Case mothers (n = 92)

> > 35 (0.38) 42 (0.46) 15 (0.16)

112 (0.61) 72 (0.39)

1

1

2.03 (0.97-4.26) 2.05 (0.78-5.41)

1.55 (0.97-2.48)

Table 2. Genotype and allele frequency of the MTHFR C677T polymorphism among control mothers and mothers with a previous child with NTD. Values in parentheses denote allele

> NTD fathers (n = 48)

21 (0.44) 22 (0.46) 5 (0.10)

64 (0.67) 32 (0.33)

Table 3. Genotype distribution and allelic frequency of the MTHFR C677T polymorphism among mothers and fathers of cases with a previous child with NTD and controls.

OR

1 1.13 (0.59-2.17) 1.01 (0.42-2.41)

1 1.03 (0.67-1.59)

ORNTD mothers1 ORNTD fathers1

1

1

1.19 (0.6-2.38) 0.76(0.26-2.26)

0.96 (0.59-1.56)

0.97-2.48), but the differences in frequencies were statistically insignificant (table 3).

Control mothers (n = 82)

> 33 (0.40) 35 (0.43) 14 (0.17)

101 ( 0.62) 63 (0.38)

frequencies (columns 2 and 3) or 95% CI (column 4)

NTD mothers (n = 48)

14 (0.29) 25 (0.52) 9 (0.19)

53 (0.55) 43 (0.45)

Values in parentheses denote allelic frequencies unless otherwise specified. 1OR (95% CI) versus controls.

general population (n = 147) (table 3).

CC CT TT

> C T

Variable Controls

Genotype CC CT TT

Allele C Allele T

(n = 147)

67 (0.46) 59 (0.40) 21 (0.14)

193 (0.66) 101 (0.34)

ratios (OR) as well as their 95% CI were computed to assess strength of association, if any, between different genotypes and NTD. We calculated the OR and associated 95% CI for individuals who were homozygous for the thermolabile variant at MTHFR (TT).

#### **3. Results**

The annual prevalence of all types of NTDs during the 3 years treated in the Service of Pediatrics and Genocology-Obstetrics at Sétif Hospital (Algeria), was 7.3, 8.2 and 7.1 NTD cases per 1000 live births and fetal deaths. The total NTDs numbered 215 and the total live births and fetal deaths were around 28,500. Therefore, the incidence of NTD at Sétif Hospital is 7.5 per 1,000 births.

Of the total NTD cases, there where 122 (56.7%) with spina bifida, 69 (32.1%) with anencephaly, 1 (0.5%) with encephalocele and 23 (10.7%) with spina bifida and anencephaly; the corresponding birth prevalence per 1000 births was 4.35 for spina bifida, 2.42 for anencephaly, 0.70 for spina bifida and anencephaly and 0.03 for encephalocoele.

Table 1. shows the characteristics of cohorts of the different types of NTD. The sex distribution among NTD cases was significantly different, 126 (58.6%) females, 88 (40.9%) males (p <0.05) and one (0.5%) unknown or indeterminate. There were also significant differences between the type of NTD with regard to the female to male sex ratio. The female sex ratio was significantly higher for anencephalics (1.76) and spina bifida and anecephalics (4.0) compared with spina bifida (1.1) (p <0.05). Of all NTD cases studied, hundred and seventeen (54.4%) cases died in utero and 4 cases (1.9%) unknown. The trend had not significantly changed for spina bifida and anencephaly during the 3 year period. The spina bifida/anencephaly ratio for the 3 year period was 1.77 (122/69).

Of the 215 NTD cases in the study, there were 64 (29.8%) with associated hydrocephalus anomalies. This study shows 13% (28/215) of the parents with affected newborns had consanguineous marriages. The rate of affected newborns was highest in mothers aged between 31-35 years (21.9%) (Tab. 1). Seasonal variation in the birth prevalence of NTD during the 3 year period was observed. Birth prevalence of NTD was higher in the January-June period (58.14%) compared with the July-December period (41.86%). The rate of NTD in May and June was 13.5 and 15.8% respectively, and was higher than for other months.


Table 1. Characteristics of cohorts of the different types of NTD.

ratios (OR) as well as their 95% CI were computed to assess strength of association, if any, between different genotypes and NTD. We calculated the OR and associated 95% CI for

The annual prevalence of all types of NTDs during the 3 years treated in the Service of Pediatrics and Genocology-Obstetrics at Sétif Hospital (Algeria), was 7.3, 8.2 and 7.1 NTD cases per 1000 live births and fetal deaths. The total NTDs numbered 215 and the total live births and fetal deaths were around 28,500. Therefore, the incidence of NTD at Sétif Hospital

Of the total NTD cases, there where 122 (56.7%) with spina bifida, 69 (32.1%) with anencephaly, 1 (0.5%) with encephalocele and 23 (10.7%) with spina bifida and anencephaly; the corresponding birth prevalence per 1000 births was 4.35 for spina bifida, 2.42 for

Table 1. shows the characteristics of cohorts of the different types of NTD. The sex distribution among NTD cases was significantly different, 126 (58.6%) females, 88 (40.9%) males (p <0.05) and one (0.5%) unknown or indeterminate. There were also significant differences between the type of NTD with regard to the female to male sex ratio. The female sex ratio was significantly higher for anencephalics (1.76) and spina bifida and anecephalics (4.0) compared with spina bifida (1.1) (p <0.05). Of all NTD cases studied, hundred and seventeen (54.4%) cases died in utero and 4 cases (1.9%) unknown. The trend had not significantly changed for spina bifida and anencephaly during the 3 year period. The spina

Of the 215 NTD cases in the study, there were 64 (29.8%) with associated hydrocephalus anomalies. This study shows 13% (28/215) of the parents with affected newborns had consanguineous marriages. The rate of affected newborns was highest in mothers aged between 31-35 years (21.9%) (Tab. 1). Seasonal variation in the birth prevalence of NTD during the 3 year period was observed. Birth prevalence of NTD was higher in the January-June period (58.14%) compared with the July-December period (41.86%). The rate of NTD in May and June was 13.5 and 15.8% respectively, and was higher than for other months.

Variable Type of defect Total ² *P*-value

Male 59 (67.0) 25 (28.4) 4 (4.5) 0 (0.0) 88 (100) 5.02 0.05

20 4 (57.1) 1 (14.3) 2 (28.6) 0 (0.0) 7 (100) 14.28 0.01

Sex

Female 65 (51.6) 44 (34.9) 16 (12.7) 1 (0.8) 126 (100)

21-25 24 (60.0) 11 (27.5) 5 (125) 0 (0.0) 40 (100) 26-30 23 (67.6) 9 (22.5) 2 (59) 0 (0.0) 34 (100) 31-35 20 (42.5) 22 (46.8) 5 (10.6) 0 (0.0) 47 (100) 36 21 (56.7) 13 (35.1) 2 (5.4) 1 (2.7) 37 (100) Consanguinity 16 (57.1) 9 (32.1) 3 (10.7) 0 (0.0) 28 (100) Death 30 (25.6) 64 (54.7) 23 (19.6) 0 (0.0) 117 (100)

No. (%) No. (%) No. (%) No. (%) No. (%)

+Anencephaly Encephalocele

individuals who were homozygous for the thermolabile variant at MTHFR (TT).

anencephaly, 0.70 for spina bifida and anencephaly and 0.03 for encephalocoele.

bifida/anencephaly ratio for the 3 year period was 1.77 (122/69).

bifida Anencephaly Spina bifida

Table 1. Characteristics of cohorts of the different types of NTD.

Spina

Mother's age (y)

**3. Results** 

is 7.5 per 1,000 births.

The observed frequencies of the various genotypes and alleles of C677T polymorphisms in the *MTHFR* gene are shown in Table 2. Forty-two (46%) out of 92 mothers analysed for the C677T polymorphism carried the T allele and 15 (16%) were homozygotes (table 2). Finally, 5 (10%) out of 48 fathers had the TT genotype and 22 (46%) were heterozygotes (Tab. 2). In the control mothers group (n = 82), 35 (43%) were heterozygotes (table 3). In the control mothers group (n = 82), 35 (43%) were heterozygotes and 14 (17%) were homozygotes (table 2). These frequencies were not significantly different from those observed in a sample of the general population (n = 147) (table 3).

There was no statistically significant difference between the genotype and allele frequencies of C677T polymorphisms in mothers with a previous child with NTD compared with mother controls. The allele frequencies for the MTHFR C677T polymorphism were similar in case mothers and control mothers, with approximate allele frequencies of 0.6 and 0.3 for C and T alleles, respectively (table 2). Comparisons of genotype frequencies between case mothers and controls did not reveal any statistically significant differences (tables 2, 3).

The frequency of C677T homozygotes in the couple was higher in mothers with a previous child with NTD than in corresponding controls (19 vs. 14%), but the difference was not statistically significant. The OR was 2.05 (95% CI: 0.78-5.41) (table 2). The frequency of T alleles too was higher in case mothers compared to controls (45 vs. 34%; OR = 1.55; 95% CI: 0.97-2.48), but the differences in frequencies were statistically insignificant (table 3).


Table 2. Genotype and allele frequency of the MTHFR C677T polymorphism among control mothers and mothers with a previous child with NTD. Values in parentheses denote allele frequencies (columns 2 and 3) or 95% CI (column 4)


Values in parentheses denote allelic frequencies unless otherwise specified. 1OR (95% CI) versus controls.

Table 3. Genotype distribution and allelic frequency of the MTHFR C677T polymorphism among mothers and fathers of cases with a previous child with NTD and controls.

Neural Tube Defects in Algeria 169

observation is different from other studies which show a linear relation between the rate of NTD and increasing maternal age (Golalipour et al., 2007) or which show, a U-shaped curve with a higher risk among younger mothers and higher rates in mothers aged over 35 years (Hendricks et al., 1999; Li et al., 2006). It may be due to factors such as lower rate of marriage under 20 years (sometimes even more than 25 years of age) and can be attributed to the use

In this study a seasonal variation in the birth prevalence of NTD was observed, it was higher in the January-June period compared with July-December period, then is similar to that reported by Mc Donnell et al. (1999). Some research has shown a predominance of NTD births in winter months particularly in October to December and January to March (Golalipour et al., 2007; Office for Population Censuses and Surveys, 1998). Our research has shown that rate of NTD was higher in May with a peak in June. In Ireland the peak prevalence was in April (McDonnell et al., 1999) and in Northern Iran it was in December (Golalipour et al., 2007). The seasonal variations in the birth prevalence and the peak of NTD observed in our population were difficult to compare with those of previous studies, which were performed in countries where income, seasonal changes in diet is completely different. The high prevalence of NTD it may be attributed to the low dietary intake of folate in our women population (Houcher et al., 2003) and related with the seasonal variation of folate consumption. For example, the folate dietary intake of Havanan men was lowest in June and July, which contrasts with improvement in folate intake in June and July observed in Gambian women ( Bates et al., 1994), and with the increase in serum folate concentration

It has shown that the rate of consanguineous marriage is high in NTD births (Murshid, 2000). In different Middle Eastern countries the rate of consanguineous marriages varies from 23.3% to 57.9% (Khoury & Massad, 1992; Teebi, 1994) The incidence of consanguineous marriage in Algeria was 23-34% (Benallegue & Kedji 1984; Zaoui & Biemont, 2002) and the frequency of consanguineous marriage rates were 40.5 and 30.6% in rural and urban settings, respectively (Zaoui & Biemont, 2002). First-cousin marriages constitute almost onethird of all marriages in many Arab countries (Hamamy et al., 2005). First-cousin marriage in Algeria was 10-16% (Zaoui & Biemont, 2002). In our study 13% of parents with affected newborns had consanguineous marriage (first-cousin). In families with children born with neural tube defects, the consanguinity rate was much higher than observed in the general population (Jaber et al., 2004; Khrouf et al., 1986; Zlotogora, 1997). The relatively high proportion of first cousin marriages among parents of individuals with neural tube defects suggests that some of these cases are due to monogenic disorders (Zlotogora, 1997). We were not able to confirm the suggestion that there is an increase risk for NTD in children born of consanguineous parents. The possibility that consanguinity could be a risk factor for

NTD in a population requires further research (Murshid, 2000; Rajab et al., 1998).

Numerous articles have been published regarding the effect of folic acid intake on the reduction or prevention of NTD (Frey & Hauser, 2003; Li et al., 2006; Morin et al., 2001; Smithells et al., 1980; Stevenson et al., 2000). Intake of 0.4 mg per day of folic acid in the periconceptional period reduces the risk of NTD by 30-100% (Berry et al., 1999; Czeizel and Dudas, 1992; MRC Vitamin Study Research Group, 1991; Ray et al., 2002). Several studies have suggested that low vitamin B12 levels may be associated with an increased risk for

of contraceptive drugs using over 35 years.

during the summer observed in British men (Clarke et al., 1998).

#### **4. Discussion**

Neural tube defects are a worldwide problem, affecting an estimated 300,000 or more fetus or infants each year (The Centers for Disease Control and prevention (CDC), 1998). The reported annual percentage fall in the rates of NTD was 3.1-7.7% for the United States and 10.6% for the United Kingdom (Windham & Edmands, 1982). Unfortunately we do not have previous data from our area or in all Algeria for comparison. This is the first report regarding NTD in Sétif (Algeria). Our study showed the incidence was 7.5 cases per 1,000. The trend over the 3 years remained fairly constant. Our rate is higher than studies in other countries such as Canada where it was 1.41/1,000 (DeWalls et al., 1992; Murphy, 1992; Van Allen et al., 1992; Wilson & Van Allen , 1993), in the United States of America 0.93 to 1.46/1,000 (Hendricks et al., 1999; Stevenson et al., 2000), in Germany 1.50/1,000 (Koch & Fuhrmann, 1984), in Holland 0.58/1,000 (Eurocat Working Group, 1991), in the North of England 1.79/1,000 (Rankin et al., 2000), in France 1,000 (Alembik et al., 1995; Candito & Van Obberghen, 2001), in Italy 0.36/1,000 (Eurocat Working Group, 1991), in South Africa 1.74/1,000 (Buccimazza et al., 1994), in Turkey 3.01/1,000 (Tuncbilek et al., 1999), in Jordan 1.63/1000 (Daoud et al., 1996), Palestine 5.49/1000 (Dudin, 1997), in United Arab Emirates 1.23/1000 (Samson, 2003), in Tunisia 2.2/1000 (Khrouf et al., 1986) and in Iran 2.87/1,000 (Golalipour et al., 2007). A higher prevalence in comparison with our results was observed in China 10.23-13.87/1000 (Dai et al., 2002; Li et al., 2006; Xiao et al., 1990) and Egypt 13.8/1000 (Samaha et al., 1995).

Spina bifida was the most common NTD in our study, which agrees with other studies (Golalipour et al., 2007; Harris & James, 1997; Soumaya et al., 2001; Wasant & Sathienkijkanchai, 2005), followed by anencephaly and encephalocele. The spina bifida to anencephalic ratio is similar to that reported by other workers (McDonnell et al., 1999). Our research was shown that more than half of mortality is a consequence of anencephaly (Eurocat Working Group, 1991).

In our study, there were 64 spina bifida (29.8%) with associated hydrocephalus anomalies. The etiology of congenital hydrocephalus is extremely heterogeneous and for instance it may be secondary to an open neural tube defect (Williamson et al., 1984). In general, patients with spina bifida, not including anencephaly and encephalocele, will have 80 to 85% chance of developing hydrocephallus (Rintoul et al., 2002). Also, it has been suggested that there is an increased risk for hydrocephalus in families with a propositus affected with NTD (Cohen et al., 1979).

As reported in many other studies (Lary & Paulozzi, 2001; Rittler et al., 2004), we also observed a significant females predominance. Regarding sex differences, our results indicate that the rate of NTD was higher in females than males (male to female ratio = 0.70). Others had reported 0.73 (Daoud et al., 1996), 0.78 (Golalipour et al., 2007; Stevenson et al., 2000) and 0.85 (Samson, 2003), or even a male predominance 1.07 (Wasant & Sathienkijkanchai, 2005). The predominance of female anencephalic births over males in our study is similar to that seen in other countries and likewise the slight female predominance in spina bifida births (McDonnell et al., 1999).

Our research showed that the highest rate of affected newborns was in mothers aged 31-35 years (21.9%), with 3.2% in mothers aged 16-20 years and 9.76% aged 36-40 years. Our

Neural tube defects are a worldwide problem, affecting an estimated 300,000 or more fetus or infants each year (The Centers for Disease Control and prevention (CDC), 1998). The reported annual percentage fall in the rates of NTD was 3.1-7.7% for the United States and 10.6% for the United Kingdom (Windham & Edmands, 1982). Unfortunately we do not have previous data from our area or in all Algeria for comparison. This is the first report regarding NTD in Sétif (Algeria). Our study showed the incidence was 7.5 cases per 1,000. The trend over the 3 years remained fairly constant. Our rate is higher than studies in other countries such as Canada where it was 1.41/1,000 (DeWalls et al., 1992; Murphy, 1992; Van Allen et al., 1992; Wilson & Van Allen , 1993), in the United States of America 0.93 to 1.46/1,000 (Hendricks et al., 1999; Stevenson et al., 2000), in Germany 1.50/1,000 (Koch & Fuhrmann, 1984), in Holland 0.58/1,000 (Eurocat Working Group, 1991), in the North of England 1.79/1,000 (Rankin et al., 2000), in France 1,000 (Alembik et al., 1995; Candito & Van Obberghen, 2001), in Italy 0.36/1,000 (Eurocat Working Group, 1991), in South Africa 1.74/1,000 (Buccimazza et al., 1994), in Turkey 3.01/1,000 (Tuncbilek et al., 1999), in Jordan 1.63/1000 (Daoud et al., 1996), Palestine 5.49/1000 (Dudin, 1997), in United Arab Emirates 1.23/1000 (Samson, 2003), in Tunisia 2.2/1000 (Khrouf et al., 1986) and in Iran 2.87/1,000 (Golalipour et al., 2007). A higher prevalence in comparison with our results was observed in China 10.23-13.87/1000 (Dai et al., 2002; Li et al., 2006; Xiao et al., 1990) and Egypt

Spina bifida was the most common NTD in our study, which agrees with other studies (Golalipour et al., 2007; Harris & James, 1997; Soumaya et al., 2001; Wasant & Sathienkijkanchai, 2005), followed by anencephaly and encephalocele. The spina bifida to anencephalic ratio is similar to that reported by other workers (McDonnell et al., 1999). Our research was shown that more than half of mortality is a consequence of anencephaly

In our study, there were 64 spina bifida (29.8%) with associated hydrocephalus anomalies. The etiology of congenital hydrocephalus is extremely heterogeneous and for instance it may be secondary to an open neural tube defect (Williamson et al., 1984). In general, patients with spina bifida, not including anencephaly and encephalocele, will have 80 to 85% chance of developing hydrocephallus (Rintoul et al., 2002). Also, it has been suggested that there is an increased risk for hydrocephalus in families with a propositus affected with

As reported in many other studies (Lary & Paulozzi, 2001; Rittler et al., 2004), we also observed a significant females predominance. Regarding sex differences, our results indicate that the rate of NTD was higher in females than males (male to female ratio = 0.70). Others had reported 0.73 (Daoud et al., 1996), 0.78 (Golalipour et al., 2007; Stevenson et al., 2000) and 0.85 (Samson, 2003), or even a male predominance 1.07 (Wasant & Sathienkijkanchai, 2005). The predominance of female anencephalic births over males in our study is similar to that seen in other countries and likewise the slight female predominance in spina bifida

Our research showed that the highest rate of affected newborns was in mothers aged 31-35 years (21.9%), with 3.2% in mothers aged 16-20 years and 9.76% aged 36-40 years. Our

**4. Discussion** 

13.8/1000 (Samaha et al., 1995).

(Eurocat Working Group, 1991).

NTD (Cohen et al., 1979).

births (McDonnell et al., 1999).

observation is different from other studies which show a linear relation between the rate of NTD and increasing maternal age (Golalipour et al., 2007) or which show, a U-shaped curve with a higher risk among younger mothers and higher rates in mothers aged over 35 years (Hendricks et al., 1999; Li et al., 2006). It may be due to factors such as lower rate of marriage under 20 years (sometimes even more than 25 years of age) and can be attributed to the use of contraceptive drugs using over 35 years.

In this study a seasonal variation in the birth prevalence of NTD was observed, it was higher in the January-June period compared with July-December period, then is similar to that reported by Mc Donnell et al. (1999). Some research has shown a predominance of NTD births in winter months particularly in October to December and January to March (Golalipour et al., 2007; Office for Population Censuses and Surveys, 1998). Our research has shown that rate of NTD was higher in May with a peak in June. In Ireland the peak prevalence was in April (McDonnell et al., 1999) and in Northern Iran it was in December (Golalipour et al., 2007). The seasonal variations in the birth prevalence and the peak of NTD observed in our population were difficult to compare with those of previous studies, which were performed in countries where income, seasonal changes in diet is completely different. The high prevalence of NTD it may be attributed to the low dietary intake of folate in our women population (Houcher et al., 2003) and related with the seasonal variation of folate consumption. For example, the folate dietary intake of Havanan men was lowest in June and July, which contrasts with improvement in folate intake in June and July observed in Gambian women ( Bates et al., 1994), and with the increase in serum folate concentration during the summer observed in British men (Clarke et al., 1998).

It has shown that the rate of consanguineous marriage is high in NTD births (Murshid, 2000). In different Middle Eastern countries the rate of consanguineous marriages varies from 23.3% to 57.9% (Khoury & Massad, 1992; Teebi, 1994) The incidence of consanguineous marriage in Algeria was 23-34% (Benallegue & Kedji 1984; Zaoui & Biemont, 2002) and the frequency of consanguineous marriage rates were 40.5 and 30.6% in rural and urban settings, respectively (Zaoui & Biemont, 2002). First-cousin marriages constitute almost onethird of all marriages in many Arab countries (Hamamy et al., 2005). First-cousin marriage in Algeria was 10-16% (Zaoui & Biemont, 2002). In our study 13% of parents with affected newborns had consanguineous marriage (first-cousin). In families with children born with neural tube defects, the consanguinity rate was much higher than observed in the general population (Jaber et al., 2004; Khrouf et al., 1986; Zlotogora, 1997). The relatively high proportion of first cousin marriages among parents of individuals with neural tube defects suggests that some of these cases are due to monogenic disorders (Zlotogora, 1997). We were not able to confirm the suggestion that there is an increase risk for NTD in children born of consanguineous parents. The possibility that consanguinity could be a risk factor for NTD in a population requires further research (Murshid, 2000; Rajab et al., 1998).

Numerous articles have been published regarding the effect of folic acid intake on the reduction or prevention of NTD (Frey & Hauser, 2003; Li et al., 2006; Morin et al., 2001; Smithells et al., 1980; Stevenson et al., 2000). Intake of 0.4 mg per day of folic acid in the periconceptional period reduces the risk of NTD by 30-100% (Berry et al., 1999; Czeizel and Dudas, 1992; MRC Vitamin Study Research Group, 1991; Ray et al., 2002). Several studies have suggested that low vitamin B12 levels may be associated with an increased risk for

Neural Tube Defects in Algeria 171

homocysteine levels. The high prevalence of the *MTHFR 677T* allele (17%) (Bourouba et al., 2009), the higher risk of NTD (7.5 per 1,000 births) (Houcher et al., 2008) and lower daily folate intake (69%) of less than the reference nutrient intake for folate (Houcher et al., 2003), i.e. a combination of genetic and nutritional factors, may therefore play a role in the NTD rate in this region of Algeria, although the mechanism, by which the genotype or folate

Our results support the hypothesis by Shields et al. (1999), which upholds that the 677T allele may only be a risk factor in populations with a poor folate diet, which could explain the lack of consistency among studies. Molloy et al. (1997) observed a decreased red cell folate in individuals that were homozygous for the C677T mutation. Consequently, the MTHFR A1298C variant was found to increase the risk of spina bifida when combined with MTHFR C677T alteration (Akar et al., 2000). However, it cannot be excluded that mutations of folate receptor genes correlate with NTD (De Marco et al., 2000) and can be involved in

Currently, the molecular analysis in case of NTD is based on the examination of mutation (polymorphism) in genes, which is why it is difficult to determine their genetic basis. It seems that NTD diagnosis will be based on single nucleotide polymorphism analysis (Gos and Szpecht-Potocka, 2002). It has been established that the dihydrofolate reductase (DHFR) 19-bp intron deletion allele has a significant protective association by reducing the risk of woman having NTD of offspring in the Irish population (Parle-McDermott et al., 2007). Very recently, it has been reported that NTD mothers homozygous for the 19-bp del allele have a 2.04-fold greater risk compared to the controls in the Turkish population (Akar et al., 2008). In addition, Au et al. (2008) also found that several genes for glucose transport and

Several studies even pointed out that a folate intake high enough to prevent NTD cannot be achieved by a diet of folate–rich nutrition. Only intake of folate supplements or fortified foods such as flour and cereals can achieve these recommended daily values (van der Put et al., 1998). In terms of public health, we think that the most important finding from this study is the very low periconceptional use of folic-acid–containing vitamins among our population

According to our findings genetic factors, interfamilial marriage and nutritional factors as folate deficiency may play a role in the NTD rate in this region of Algeria, although the mechanism, by which the genotype or folate status increases the risk of NTD, is not clear. So further investigations are needed, and we recommend that a central registry be set up to

Several studies even pointed out that a folate intake high enough to prevent NTD cannot be achieved by a diet of folate–rich nutrition. Only intake of folate supplements or fortified foods such as flour and cereals can achieve these recommended daily values. In terms of public health, we think that the most important finding from this study is the very low periconceptional use of folic-acid–containing vitamins among our population of

status increases the risk of NTD is not clear.

metabolism are potential risk factors for meningomyolocele.

NTD etiology (Heil et al, 1999).

of women.

women.

**5. Conclusion** 

record NTD occurring in the Sétif region.

NTD (Candito et al., 2004; Kirke et al., 2004; Williams et al., 2005). Our NTD group showed a higher risk of NTD among our women population, which may in part be attributable to a lower daily folate intake of women in our previous report; it revealed a large proportion of women (69%) presenting with less than the Reference Nutrient Intake (RNI) for folate (Houcher et al., 2003). Possibly, the most important finding from this study was the very low periconceptional use of folic acid-containing vitamins among our women population. Only 2.4% women in our population consumed multivitamins daily (Houcher et al., 2003).

NTD is recognized to have a complex etiology, involving both environmental and genetic factors. The *MTHFR* gene is chosen for study because of its direct catalytic interaction with homocysteine, cobalamin and folate, which predicted risk factors in NTD (Kirke et al., 1993; van der Put et al., 1997). It has been shown that homozygosity for the common C677T mutation in the *MTHFR* gene is a genetic risk factor for NTD in man (van der Put et al., 1995; Ou et al., 1995).

The association between the C677T variant in the *MTHFR* gene and NTD is controversial in several populations worldwide. Our research is the first in Algeria, which studied NTD patients in order to determine the association of the T allele with NTD in the region of Sétif, where NTD are highly prevalent (Houcher et al., 2008). The MTHFR C677T gene polymorphism was neutral in our population. We found the same prevalence of the 677T *MTHFR* allele in mothers as in controls and in the general population. Our results on Algerian NTD mothers did not show a significant association for any group, suggesting that the thermolabile variant C677T in the MTHFR gene is not a risk factor for NTD for a mother to have NTD offspring. These data are not in agreement with those of others (Grandone et al., 2006), who reported a higher prevalence in mothers than in controls and in the general population. However, no association was found for mothers of offspring with NTD in Italy or in Ireland, two countries with a higher 677 T allele frequency (De Marco et al., 2002; Kirke et 2004).

Thus, homozygosity for *MTHFR 677T* may only be a risk factor for NTD in some ethnic groups and not in others (Papapetrou et al., 1996). The divergence between populations raises the question whether dietary factors could play a significant interactive role in C677T mutations. There is evidence that the risk for NTD in association with the *MTHFR* genotypes might vary depending on the nutritional status (Gonzalez-Herrera et al., 2002) and, especially, due to low levels of red cell folate (Martinez de Villarreal et al., 2001). It is also relevant to note that the incidence of the C677T variant differs markedly amongst populations. These differences do not correlate with the incidence of NTD; for example, the frequency of homozygosity for the 677T allele is 8.3% in Ireland where the prevalence of NTD is high, and 16% in Italy where the NTD prevalence is low (Morrison et al., 1998).

Davalos et al (2000), who included among their cases the mothers and fathers of children affected by NTD, also found no differences between the cases and the control groups concerning the maternal genotype or allelic frequencies. We found that mothers who are homozygous for the C677T mutation, have a 4-fold higher risk of having a child with an NTD. Thus, the *MTHFR* genotype of the father also contributes to the risk of NTD (Blom, 1998)

The thermolabile MTHFR C677T variant is a risk factor for NTD in some but not all populations (Botto and Yang, 2000) and is associated with low folate and elevated

NTD (Candito et al., 2004; Kirke et al., 2004; Williams et al., 2005). Our NTD group showed a higher risk of NTD among our women population, which may in part be attributable to a lower daily folate intake of women in our previous report; it revealed a large proportion of women (69%) presenting with less than the Reference Nutrient Intake (RNI) for folate (Houcher et al., 2003). Possibly, the most important finding from this study was the very low periconceptional use of folic acid-containing vitamins among our women population. Only 2.4% women in our population consumed multivitamins daily (Houcher et al., 2003). NTD is recognized to have a complex etiology, involving both environmental and genetic factors. The *MTHFR* gene is chosen for study because of its direct catalytic interaction with homocysteine, cobalamin and folate, which predicted risk factors in NTD (Kirke et al., 1993; van der Put et al., 1997). It has been shown that homozygosity for the common C677T mutation in the *MTHFR* gene is a genetic risk factor for NTD in man (van der Put et al.,

The association between the C677T variant in the *MTHFR* gene and NTD is controversial in several populations worldwide. Our research is the first in Algeria, which studied NTD patients in order to determine the association of the T allele with NTD in the region of Sétif, where NTD are highly prevalent (Houcher et al., 2008). The MTHFR C677T gene polymorphism was neutral in our population. We found the same prevalence of the 677T *MTHFR* allele in mothers as in controls and in the general population. Our results on Algerian NTD mothers did not show a significant association for any group, suggesting that the thermolabile variant C677T in the MTHFR gene is not a risk factor for NTD for a mother to have NTD offspring. These data are not in agreement with those of others (Grandone et al., 2006), who reported a higher prevalence in mothers than in controls and in the general population. However, no association was found for mothers of offspring with NTD in Italy or in Ireland, two countries with a higher 677 T allele frequency (De Marco et al., 2002; Kirke

Thus, homozygosity for *MTHFR 677T* may only be a risk factor for NTD in some ethnic groups and not in others (Papapetrou et al., 1996). The divergence between populations raises the question whether dietary factors could play a significant interactive role in C677T mutations. There is evidence that the risk for NTD in association with the *MTHFR* genotypes might vary depending on the nutritional status (Gonzalez-Herrera et al., 2002) and, especially, due to low levels of red cell folate (Martinez de Villarreal et al., 2001). It is also relevant to note that the incidence of the C677T variant differs markedly amongst populations. These differences do not correlate with the incidence of NTD; for example, the frequency of homozygosity for the 677T allele is 8.3% in Ireland where the prevalence of NTD is high, and 16% in Italy where the NTD prevalence is low (Morrison et al., 1998).

Davalos et al (2000), who included among their cases the mothers and fathers of children affected by NTD, also found no differences between the cases and the control groups concerning the maternal genotype or allelic frequencies. We found that mothers who are homozygous for the C677T mutation, have a 4-fold higher risk of having a child with an NTD. Thus, the *MTHFR* genotype of the father also contributes to the risk of NTD (Blom, 1998)

The thermolabile MTHFR C677T variant is a risk factor for NTD in some but not all populations (Botto and Yang, 2000) and is associated with low folate and elevated

1995; Ou et al., 1995).

et 2004).

homocysteine levels. The high prevalence of the *MTHFR 677T* allele (17%) (Bourouba et al., 2009), the higher risk of NTD (7.5 per 1,000 births) (Houcher et al., 2008) and lower daily folate intake (69%) of less than the reference nutrient intake for folate (Houcher et al., 2003), i.e. a combination of genetic and nutritional factors, may therefore play a role in the NTD rate in this region of Algeria, although the mechanism, by which the genotype or folate status increases the risk of NTD is not clear.

Our results support the hypothesis by Shields et al. (1999), which upholds that the 677T allele may only be a risk factor in populations with a poor folate diet, which could explain the lack of consistency among studies. Molloy et al. (1997) observed a decreased red cell folate in individuals that were homozygous for the C677T mutation. Consequently, the MTHFR A1298C variant was found to increase the risk of spina bifida when combined with MTHFR C677T alteration (Akar et al., 2000). However, it cannot be excluded that mutations of folate receptor genes correlate with NTD (De Marco et al., 2000) and can be involved in NTD etiology (Heil et al, 1999).

Currently, the molecular analysis in case of NTD is based on the examination of mutation (polymorphism) in genes, which is why it is difficult to determine their genetic basis. It seems that NTD diagnosis will be based on single nucleotide polymorphism analysis (Gos and Szpecht-Potocka, 2002). It has been established that the dihydrofolate reductase (DHFR) 19-bp intron deletion allele has a significant protective association by reducing the risk of woman having NTD of offspring in the Irish population (Parle-McDermott et al., 2007). Very recently, it has been reported that NTD mothers homozygous for the 19-bp del allele have a 2.04-fold greater risk compared to the controls in the Turkish population (Akar et al., 2008). In addition, Au et al. (2008) also found that several genes for glucose transport and metabolism are potential risk factors for meningomyolocele.

Several studies even pointed out that a folate intake high enough to prevent NTD cannot be achieved by a diet of folate–rich nutrition. Only intake of folate supplements or fortified foods such as flour and cereals can achieve these recommended daily values (van der Put et al., 1998). In terms of public health, we think that the most important finding from this study is the very low periconceptional use of folic-acid–containing vitamins among our population of women.

#### **5. Conclusion**

According to our findings genetic factors, interfamilial marriage and nutritional factors as folate deficiency may play a role in the NTD rate in this region of Algeria, although the mechanism, by which the genotype or folate status increases the risk of NTD, is not clear. So further investigations are needed, and we recommend that a central registry be set up to record NTD occurring in the Sétif region.

Several studies even pointed out that a folate intake high enough to prevent NTD cannot be achieved by a diet of folate–rich nutrition. Only intake of folate supplements or fortified foods such as flour and cereals can achieve these recommended daily values. In terms of public health, we think that the most important finding from this study is the very low periconceptional use of folic-acid–containing vitamins among our population of women.

Neural Tube Defects in Algeria 173

Buccimazza, S. ; Molteno, C. ; Dunne, T. & Viljoen, DL. (1994). Prevalence of neural tube

Candito, M.; Houcher, B.; Boisson, C.; Abbellard, A.; Demarcq, MJ.; Gueant, JL.; Benhacine,

Cohen, T.; Stern, E. & Rosenman, A. (1979). Sub risk of neural tube defect. Is prenatal

Copp, AJ.; Brook, FA.; Estibeiro, JP.; Shum, AS. & Cockroft DL. (1990). The embryonic

Czeizel, AE. & Dudas, I. (1992). Prevention of the first occurrence of neural tube defects by

Dai, L.; Zhu, J.; Zhou, G.; Wang, Y.; Wu, J.; Miao, L. & Liang, J. (2002). Dynamic monitoring

D'Angelo, A. ; Coppola, A. ; Madonna, P. ; Fermo, L., Pagano, A. ; Mazzola, G. ; Galli, L. &

Daoud, AS.; Al-Kaysi, F.; El-Shanti, H.; Batieha, A.; Obeidat, A. & Al-Sheyyab, M. (1996).

Davalos, IP.; Olivares, N.; Castillo, MT.; Cantu, JM.; Ibarra, B.; Sandoval, L.; Moran, MC.;

De Marco, P.; Calevo, MG.; Moroni, A.; Arata, L.; Merello, E.; Finnell, RH.; Zhu, H.;

DeWalls, P.; Trochet, C. & Pinsonneaut, L. (1992). Prevalence of neural tube defect in the province of Quebec. *Can J Pub Health*, Vol.90, pp. 237-239, ISSN 0008-4263

*Hemost*, Vol.15, pp. 529-534, ISNN 1076-0296

*Med Genet*, Vol.16, pp. 14-16, ISNN0022-2593

ISSN 1530-8561

403, ISNN 0301-0082

pp. 402-405, ISNN 0253-9624

*Genet*,Vol.47, pp. 319-324, ISSN 0002-9297

ISSN 0028-4793

ISSN 0340-6245

5284

0003-3995

20210 G-A mutations in healthy populations in Sétif, Algeria. *Clin Appl Thromb* 

defects in Cape Town, South Africa. *Teratology*, Vol.50, pp. 194-199, ISNN 0040-3709

K.; Gérard, P. & Van Obberghen, E. (2004). Neural tube defects and vitamin B12 : a report of three cases. *Ann Biol Clin (Paris)*, Vol.62, pp. 235-238, ISSN 0003-3898 Candito, M. & , Van Obberghen E. (2001). Folates, vitamine B12, homocystéine et anomalies du tube neural. *Ann Biol Clin (Paris)*, Vol.59, pp. 111-112, ISNN 0003-3898 Clarke, R.; Woodhouse, P.; Ulvik, A.; Frost, C.; Sherliker, P.; Refsum, H.; Ueland, PM. &

Khaw, KT. (1998). Variability and determinants of total homocysteine concentrations in plasma in an elderly population. *Clin Chem*, Vol.44, pp. 102-107,

diagnosis indicated in pregnancies following the birth of a hydrocephalic child? *J* 

development of mammalian neural tube defects. *Progr Neurobiol*, Vol.35, pp. 363-

periconceptional vitamin supplementation. *N Engl J Med*, Vol.327, pp. 1832-1835,

of neural tube defects in China during 1996 to 2000. *Chinese J Prevent Med*, Vol.36,

Cerbone, AM. (2000). The role of vitamin B12 in fasting hyperhomocysteinemia and its interaction with the homozygous C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene. A case-control study of patients with early-onset thrombotic events. *Thromb Haemost*, Vol.83, pp. 563-70,

Neural tube defects in Northern Jordan. *Saud Med J*, Vol.17, pp. 78-81, ISSN 0379-

Gallegos, MP., Chakraborty, R. & Rivas F. (2000). The C677T polymorphism of the methylenetetrahydrofolate reductase gene in Mexican mestizo neural tube defect parents, control mestizo and native populations. *Ann Genet*, Vol.43, pp. 89-92, ISSN

Andreussi, L.; Cama, A. & Capra, V. (2002). Study of MTHFR and MS polymorphisms as risk factors for NTD in the Italian population. *J Hum* 

#### **6. Acknowledgment**

This study was supported in part by Ankara University, Turkey. We extend our special thanks to the personnel of the newborns and delivery sections at the Setif University Maternity Hospital, Algeria, and the families who participated in this study.

#### **7. References**


This study was supported in part by Ankara University, Turkey. We extend our special thanks to the personnel of the newborns and delivery sections at the Setif University

Afman, LA. ; Lievers, KJA. ; Kluijtmans, LAJ. ; Trijbels, FJM. & Blom, HJ. (2003). Gene-gene

Akar, N.; Akar, E.; Deda, G. & Arsan, S. (2000). Spina bifida and common mutations at the

Akar, N.; Akar, E.; Eğin, Y.; Deda, G.; Arsan, S. & Ekim, M. (2008). Neural tube defects and

Alembik, Y.; Dott, B.; Roth, MP. & Stoll, C. (1995). Prevalence of neural tube defects in

Almawi, WY.; Finan, RR.; Tamim, H.; Daccache, JL. & Irani-Hakime, N. (2004). Differences

Au, KS.; Tran, PX.; Tsai, CC.; O'Byrne, MR.; Lin, J-I.; Morrison, AC.; Hampson, AW.; Cirino,

Bates, CJ.; Prentice, AM.; & Paul, AA. (1994). Seasonal variations in vitamins A, C, riboflavin

Benallegue, A. & Kedji, F. (1984). Consanguinité et santé publique: Une étude algérienne.

Berry, RJ.; Li, Z.; Erickson, JD.; Li, S.; Moore, CA.; Wang, H.; Mulinare, J.; Zhao, P.; Wong,

Blom, HJ. (1998). Mutated 5,10-methylenetetrahydrofolatereductase and moderate hyperhomocysteinemia. *Eur J Pediatr*, Vol.157, pp. S131-S134, ISSN 0340-6199 Botto, LD. & Yang, Q. (2000). 5,10-Methylenetetrahydrofolate reductase gene variants and

Bourouba, R., Houcher, B., Djabi, F., Egin, Y. & Akar, N. (2009). The prevalence of

Prevention. *N Engl J Med*, Vol.341, pp. 1485-1490, ISNN 0028-4793

*Arch Fr Pédiatr*, Vol.41, pp. 435-40, ISSN 0003-9764

interaction between the cystathionine -synthase 31 base pair variable number of tandem repeats and the methylenetetrahydrofolate reductase 677C>T polymorphism on homocysteine levels and risk for neural tube defects. *Mol Gent* 

homocysteine metabolism pathway. *Clin Genet*, Vol.57, pp. 230-231, ISSN 0009-9163

19 bp deletion within intron-1 of dihydrofolate reductase gene. *Turk J Med Sci*,

northeastern France, 1979-1992 impact of prenatal diagnosis. *Ann Genet*, Vol.38, pp.

in the frequency of the C677T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene among the Lebanese population. *Am J Hematol*, Vol.76, pp. 85-87,

P.; Fletcher, JM.; Ostermaier, KK.; Tyerman, GH.; Doebel, S. & Northrup, H. (2008). Characteristics of a spina bifida population including north American Caucasian and Hispanic individuals. *Birth Defects Research A ,* Vol.82, pp. 692-700, ISNN 1542-

and folate intake and status of pregnant and lactating women in a rural Gambian community: some possible implications. *Eur J Clin Nutr*, Vol.48, pp. 660-668, ISSN

LY.; Gindler, J.; Hong, SX. & Correa, A. (1999). Prevention of neural tube defects with folic acid in China. China-U.S. Collaborative Project for Neural Tube Defect

congenital anomalies: a HuGe review. *Am J Epidemiol*, Vol.151, pp. 862-877, ISSN

methylenetetrahydrofolate reductase 677 C-T, factor V 1691 G-A, and prothrombin

Maternity Hospital, Algeria, and the families who participated in this study.

*Metab*, Vol.78, pp. 211-215, ISSN 1096-7192

Vol.38, pp. 383-386, ISSN 1300-0144

49-53, ISNN 0003-3995

ISSN 0361-8609

0752

0954-3007

0002-9262

**6. Acknowledgment** 

**7. References** 

20210 G-A mutations in healthy populations in Sétif, Algeria. *Clin Appl Thromb Hemost*, Vol.15, pp. 529-534, ISNN 1076-0296


Neural Tube Defects in Algeria 175

Khrouf, N. ; Spang, R. ; Podgorna, T. ; Miled, SB.; Moussaoui, M.; & Chibani, M. (1986).

Kirke, PN.; Mills, J.; Molloy, AM.; Brody, LC.; O'Leary, VB.; Daly, L.; Murray, S.; Conley, M.;

Kirke, PN.; Molloy, AM.; Daly, LE.; Burke, H.; Weir, DG. & Scott, JM. (1993). Maternal

Koch, M. & Fuhrmann, W. (1984). Epidemiology of neural tube defects in Germany. *Hum* 

Lary, JM. & Paulozzi, LJ. (2001). Sex differences in the prevalence of human birth defects: a population-based study. *Teratology*, Vol.64, pp. 237-51, ISSN 0040-3709 Li, Z. ; Ren, A. ; Zhang, L. ; Ye, R.; Li, S.; Zheng, J.; Hong, S.; Wang, T. & Li, Z. (2006).

Martinez de Villarreal, L.; Delgado-Enciso, I. ; Valdez-Leal, R. ; Ortiz-Lopez, R. ; Rojas-

McDonnell, RJ.; Johnson, Z.; Delaney, V.; & Dack P. (1999). East Ireland 1980-1994:

Molloy, A.; Daly, S.; Mills, J.; Kirke, PN.; Whitehead, AS.; Ramsbottom, D.; Conley, MR.;

Morin, VI.; Mondor, M. & Willson, RD. (2001). Knowledge on periconceptional use of folic

Morrison, K.; Papapetrou, C.; Hol, FA.; Mariman, ECM.; Lynch, SA.; Burn, J. & Edwards,

MRC Vitamin Study Research Group. (1991). Prevention of neural tube defects: results of the

Murphy, PA. (1992). Periconceptional supplementation with folic acid: does it prevent

Murshid, WR. (2000). Spina bifida in Saudi Arabia : is consanguinity among the parents a

neural defects? *J Nurse-Midwifery*, Vol.37, pp. 25-32, ISSN 0091-2182

risk factor ? *Pediatric neurosurgery*, Vol.32, pp.10-12, ISSN1016-2291

genes. *Ann Hum Genet*, Vol.62, pp. 379-396, ISSN 0003-4800

534-539, ISNN 0001-656X

0752

ISSN 0188-4409

8, ISSN 0143-005X

ISSN 0140-6736

1015-3837

6736

pp. 1535-1536, ISSN 0959-8146

*Q J Med*, Vol.86, pp. 703-708, ISSN 1460-2725

*Genet*, Vol.68, pp. 97-103, ISSN 0340-6717

Malformations in 10,000 consecutive births in Tunis. *Acta Paediatr Scand*, Vol.75, pp.

Mayne, PD.; Smith, O. & Scott, JM. (2004). Impact of the MTHFR C677T polymorphism on the risk of neural tube defect case-control study. *BMJ*, Vol.328,

plasma folate and vitamin B12 are independent risk factors for neural tube defects.

Extremely high prevalence of neural tube defects in a 4-county area in Shanxi province, China. *Birth Defects Res A Clin Mol Teratol*, Vol.76, pp. 237-240, ISSN 1542-

Martinez, A. ; Limon-Benavides, C. ; Sanchez-Pena, MA. ; Ancer-Rodriguez, J. ; Barrera-Saldana, HA. & Villarreal–Perez, JZl. (2001). Folate levels and N5,N10- Methylenetetrahydrofolate reductase genotype (MTHFR) in mothers of offspring with neural tube defects: a case-control study. *Arch medical Res*, Vol.32, pp. 277-282,

epidemiology of neural tube defects. *J Epidemiol Community Health*, Vol.53, pp. 782-

Weir, DG. & Scott, JM. (1997). Thermolabile variant of 5,10 methylenetetrahydrofolate reductase associated with low red-cell folates: implications for folate intake recommendations. *Lancet*, Vol.349, pp. 1591-1593,

acid in women of Brithsh Columbia. *Fetal Diagn. Ther*, Vol.16, pp. 111-115, ISNN

YH. (1998). Susceptibility to spina bifida; an association study of five candidate

Medical Research Council Vitamin Study. *Lancet*, Vol.338, pp. 131-137, ISSN 0140-


Dudin, A. (1997). Neural tube defects in Palestinians: a hospital based study. *Ann Trop* 

Eurocat Working Group. (1991). Prevalence of neural tube defects in 20 regions of Europe

Frey, L. & Hauser, WA. (2003). Epidemiology of neural tube defects. *Epilepsia*, Vol.44, pp. 4-

Golalipour, MJ.; Mobasheri, E.; Vakili, MA. ; & Keshtkar, AA. (2007). Epidemiology of

Gonzalez-Herrera, L.; Garcia-Escalante, G. & Castillo-Zapata, I. (2002). Frequency of the

Gos, M. & Szpecht-Potocka, A. (2002). Genetic basis of neural tube defects. II. Genes

Grandone, E.; Corrao, AM.; Colaizzo, D.; Vecchione, G.; Girgenti, CD.; Paladini, D.; Sardella,

Hamamy, H.; Jamhawi, L.; Al-Darawsheh, J.; & Ajlouni, K. (2005). Consanguineous

Harris, JA. & James, L. (1997). State-by-state cost of birth defects-1992. *Teratology*, Vol.56, pp.

Heil, SG.; van der Put, NMJ.; Trijbels, FJ.; Gabreels, FJ. & Blom, HJ. (1999). Molecular genetic

Hendricks, KA.; Nuno, OM.; Suarez, L.; & Larsen R. (2001). Effects of hyperinsulinemia and

Hendricks, KA.; Simpson, JS. & Larsen, RD. (1999) Neural tube defect along the texas-Mexico border, 1993-1995. *Am J Epidemiol*, Vol.149, pp. 1119-27, ISSN 0002-9262 Houcher, B.; Bourouba, R.; Djabi, F. & Houcher, Z. (2008). The prevalence of neural tube

Houcher, B.; Potier de Courcy, G.; Candito, M.; van Obberghen, E. & Naimi, D. (2003).

Jaber, L.; Karim, IA.; Jawdat, AM.; Fausi, M. & Merlob, P. (2004). Awareness of folic acid for

consanguineous marriages. *Ann Genet*, Vol.47, pp. 69-75, ISSN 0003-3995 Khoury, SA. & Massad, D. (1992). Consanguineous marriage in Jordan. *Am J Med Genet*,

and the impact of prenatal diagnosis 1980- 86*. J Epidemiol Community Health*, Vol.45,

neural tube defects in Northern Iran, 1998-2003. *Eastern Mediterr Health J*, Vol.3, pp.

thermolable variant C677T in the MTHFR gene and lack of association with neural tube defects in the State of the Yucatan, Mexico. *Clin Genet*, Vol.62, pp. 394-398,

correlated with folate and methionine metabolism. *J Appl Genet*, Vol.43, pp.511-524,

L.; Pellegrino, M.; Zelante, L.; Martinelli, P. & Margaglione, M. (2006). Homocysteine metabolism in families from southern Italy with neural tube defects: role of genetic and nutritional determinants. *Prenat Diagn*, Vol.26, pp.1-5, ISSN

marriages in Jordan: Why is the rate changing with time? *Clin Genet*, Vol.67, pp.

analysis of human folate receptors in neural tube defects. *Eur J Hum Genet*, Vol.7,

obesity on risk of neural tube defects among Mexican Americans. *Epidemiology*,

defects in Setif university maternity hospital, Algeria-3 years review (2004-2006).

Nutritional assessment of folate status in a population of Setif, Algeria. *Pteridines*,

prevention of neural tube defects in a community with high prevalence of

*Pediatr*, Vol.17, pp. 217-22, ISSN 0272-4936

pp. 52-8, ISNN 0143-005X

560-566, ISSN 1020-3397

511-516, ISSN 0009-9163

11-16, ISSN 0040-3709

pp. 393-396, ISSN 1018-4813

Vol.12, pp. 630-635, ISSN 1044-3983

Vol.14, pp. 138-142, ISSN 0933-4807

Vol.43, pp. 769-775, ISSN 1552-4825

*Pteridines*, Vol.19, pp. 12-18, ISSN 0933-4807

13, ISNN 0013-9580.

ISSN 0009-9163

ISSN 1234-1983

0197-3851


Neural Tube Defects in Algeria 177

Selhub, J.; Jacques, PF.; Wilson, PWF.; Rush, D. & Rosenberg, IH. (1993). Vitamin status and

Shields, DC.; Kirke, PN.; Mills, JL.; Ramsbottom, D.; Molloy, AM.; Burke, H.; Weir DG.;

Smithells, RW.; Sheppard, S.; Schorah, CJ.; Seller, MJ.; Nevin, NC.; Harris, R.; Read, AP. &

Soumaya, SG. ; Aida, M. ; Sami, M. ; Khaled, N.; Med Badis, C.; Sami, J.; Ezedine, S.; Zohra,

Stevenson, RE. ; Allen, WP. ; Pai, GS.; Best, R.; Seaver, LH.; Dean, J. & Thompson, S. (2000).

The Centers for Disease Control and prevention (CDC). (1998). Preventing Neural Tube Birth Defects: A Prevention Model and Resource Guide. Atlanta, GA 30333. Tuncbilek, E.; Boduroglo, K. & Alikasifoglu, M. (1999). Neural tube defects in Turkey:

Van Allen, MI.; Fraser, FC. ; Dallaire, L.; Allason, J.; McLeod, DR.; Andermann, E. &

van der Put, NMJ.; Gabreëls, F.; Stevens, EMB.; Smeitink, JAM.; Trijbels, FJM.; Eskes, T.; van

van der Put, NMJ.; Thomas, CMG.; Eskes, TKA.; Trijbels, FJM.; Steegers-Teunissen, RPM.;

Verrotti, A.; Tana, M.; Pelliccia, P.; Chiarelli, F. & Latini, G. (2006). Recent advances on

defects? *Am J Hum Genet,* 1998; Vol.62, pp. 1044-1051, ISSN 0002-9297 van der Put, NMJ.; Steegers-Theunissen, RPM.; Frosst, P.; Trijbels, FJM.; Eskes, TKAB.; van

*Lancet*, Vol.346, pp. 1071-1072. ISSN 0140-6736

*Disord Drug Targets*, Vol.6, pp. 25-31, ISSN 1871-5303

Vol.90, pp. 505-510, ISSN 1460-2725

mother. *Am J Hum Genet*, Vol.64, pp. 1045-1055, ISSN 0002-9297

*JAMA*, Vol.270, pp. 2693-2698. ISSN 0098-7484

*Med*, Vol.79, pp. 51-53, ISSN 0041-4131

States. *Pediatrics*, Vol.106, pp. 677-683, ISSN 0031-4005

6736

0041-4301

ISSN 0820-3946

intake as primary determinants of homocysteinemia in an elderly population.

Scott, JM. & Whitehead, AS. (1999). The 'thermolabile' variant of methylenetetrahydrofolate reductase and neural tube defects: an evaluation of genetic risk and the relative importance of the genotypes of the embryo and the

Fielding, DW. (1980). Possible prevention of neural tube defects by periconceptional vitamin supplementation. *Lancet*, Vol.1, pp. 339-40, ISSN 0140-

M.; Issam, L.; Faouzia, Z.; Hedi, R.; Hela, C. & Naima, K. (2001). Encephalocele: 26 retrospective cases at the maternal and neonatal center of La Rabta, Tunis. *Tunis* 

Decline in prevalence of neural tube defects in a high-risk region of the United

prevalence distribution and risk factors. *Turk J Pediatr*, Vol.41, pp. 299-305, ISNN

Friedman, JM. (1993). Recommendations on the use of folic acid supplementation to prevent the recurrence of neural tube defects. Clinical Teratology Committee, Canadian College of MedicalGeneticists. *Can Med Assoc J*, Vol.149, pp. 1239-1243,

den Heuvel, LP. & Blom, HJ. (1998). A second common mutation in the methylenetetrahydrofolate reductase gene: an additional risk factor for neural tube

den Heuvel, LP.; Mariman, ECM.; den Heyer, M.; Rozen, R. & Blom, HJ. (1995). Mutated methylenetetrahydrofolate reductase as a risk factor for spina bifida.

Mariman, ECM.; de Graaf-Hess, A.; Smeitink, JAM. & Blom, HJ. (1997). Altered folate and vitamin B12 metabolism in families with spina bifida offspring. *Q J Med*,

neural tube defects with special reference to valproic acid. *Endocer Metab Immune* 


Mutchinick, OM. ; Lopez, MA. ; Luna, L. ; Maxman, J. & Babinsky, VE. (1999). High

Office for Population Censuses and Surveys. (1988). Congenital malformation statistics:

Ou, CY.; Stevenson, RE.; Brown, VK.; Schwartz, CE.; Allen, WP.; Khoury; MJ., Rozen, R. &

Papapetrou, C.; Lynch, SA.; Burn, J. & Edwards, YH. (1996). Methylenetetrahydrofolate reductase and neural tube defects. Lancet, Vol.348, pp. 58, ISSN 0140-6736 Parle-McDermott, A.; Pangilinan, F.; Mills, JL.; Kirke PN.; Gibney, ER.; Troendle, J.; O'Leary,

Rajab, A. ; Vaishnav, A. ; Freeman, NV. & Patton, MA. (1998). Neural tube defects and

Rampersaud, E.; Melvin, EC.; Siegel, D.; Mehltretter, I.; Dickerson, ME.; George, TM.;

Ray, JG. ; Meier, C. ; Vermeulen, MJ. ; Boss, S.; Wyatt, PR.; & Cole, DE. (2002). Association of

Rintoul, NE. ; Sutton, LN. ; Hubbard, AM. ; Cohen, B.; Melchionni, J.; Pasquariello, PS. &

Rittler, M.; Lopez, CJ. & Castilla, EE. (2004). Sex ratio and associated risk factors for 50

Rowland, CA.; Correa, A.; Cragan, JD. & Alverson, CJ. (2006). Are encepaloceles neural tube

Samaha, I. ; Rady, M. ; Nabhan, A. & Gadallah, M. (1995). The prevalence of congenital

1994. *J Egypt Public Health Assoc*, Vol.70, pp. 595-608, ISSN 0013-2446 Samson, GR. (2003). The incidence and demography of neural tube defects in Abu Dhabi,

Collaborative group. *Clin Genet*, Vol.63, pp. 210-214, ISNN 0009-9163 Rankin, J.; Glinianaia, S. & Brown, R. (2000). The changing prevalence of neural tube defects:

*Metab*, Vol.68, pp. 461-467, ISSN 1096-7192

*Hum Genet*, Vol.57, pp. 223, ISSN 0002-9297

Vol.143, pp. 1174-1180, ISSN 1552-4825

303, ISSN 0142-6338

ISSN 0269-5022

6338

2047-8, ISSN 0140-6736

409-413, ISSN 0031-4005

*Mol Teratol*, Vol.70, pp. 13-19, ISNN 15420752

defects? *Pediatrics*, Vol. 118, pp. 916-923, ISSN 0031-4005

notifications 1981-85. London: HMSO, ISBN 0116912251

prevalence of the thermolabile methylenetetrahydrofolate reductase variant in Mexico: a country with a very high prevalence of neural tube defects. *Mol Genet* 

Oakley, GP. Jr. (1995). C677T homozygosity associated with thermolabile 5,10 methylenetetrahydrofolate reductase as a risk factor for neural tube defects. *Am J* 

VB.; Molloy, AM.; Conley, M.; Scott, JM. & Brody, LC. (2007). The 19-bp deletion polymorphism in intron-1 of dihydrofolate reductase (DHFR) may decrease rather than increase risk for spina bifida in the Irish population. *Am J Med Genet A*,

congenital hydrocephalus in the Sultanate of Oman. *J Trop Pediatr*, Vol.44, pp. 300-

Enterline, D.; Nye, JS.& Speer, MC. (2003). Updated investigations of the role of methylenetetrahydrofolate reductase in human neural tube defects. NTD

a population-based study in the north of England, 1984-96. Northern Congenital Abnormality Survey Steering Group. *Peadiatr Perinat Epidemiol*, Vol.14, pp. 104-110,

neural tube defects and folic acid food fortification in Canada. *Lancet*, Vol.360, pp.

Adzick, NS. (2002). A new look at myelomeningoceles: functional level, vertebral level, shunting, and the implications for fetal intervention. *Pediatrics*, Vol.109, pp.

congenital anomaly types: clues for causal heterogeneity. *Birth Defects Res A Clin* 

malformations at birth in Ain Shams University Maternity Hospital Cairo, Egypt,

United Arab Emirates (1992-1999). *J Torp Pediatr*, Vol.49, pp. 256-257, ISSN 0142-


**10** 

**Association of** *A80G* **Polymorphism** 

**and Interaction with** *C677T-MTHFR* 

*Laboratorio de Genética. Centro de Investigaciones Regionales.* 

 *Universidad Autónoma de Yucatán. Mérida, Yucatán,* 

Lizbeth González-Herrera et al.\*

*Distrito Federal* 

 *Mexico* 

**in the** *RFC1* **Gene with the Risk for Having Spina** 

 **Bifida-Affected Offspring in Southeast Mexico** 

*Departamento de Toxicología del Centro de Investigaciones y Estudios Avanzados,* 

Spina bifida (SB) is one of the most prevalent congenital anomalies known as neural tube defects (NTD) in Yucatan, at Southeast Mexico. NTD results from failures of normal neural tube closure between the third and fourth week of embryonic development (Chen, 2008; Ramirez-Espitia et al., 2003). The majority of NTD cases can be categorized as either anencephaly with a lack of closure in the region of the head; or spina bifida with a lack of closure below the head (Au et al., 2010). SB refers to defects in the vertebral arches that obligatorily accompany open lesions. When the neural folds remain open, the sclerotome is unable to cover the neuroepithelium and skeletogenesis occurs abnormally, leaving the midline exposed (Greene & Copp, 2009). SB encompasses several subgroups of defects including the protrusion of the nervous tissue and its covering through a defect in the vertebrae named myelomeningocele, meningocele, and lipomeningocele. Myelomeningocele is by far the most common, accounting for greater than 90% of SB cases (Au et al., 2010). Wide variations in SB prevalence based on geography, race/ethnicity, and socioeconomic level suggest that genetic and environmental factors contribute to its etiology (Chen, 2008). Maternal folate status is critical for proper neural tube closure during embryogenesis. However epidemiological studies suggest that factors other than maternal deficiency of folic acid are involved in the etiology of SB. Numerous environmental and genetic influences

Orlando Vargas-Sierra, Silvina Contreras-Capetillo, Gerardo Pérez-Mendoza, Ileana Castillo-Zapata,

Doris Pinto-Escalante, Thelma Canto de Cetina and Betzabet Quintanilla-Vega

*Departamento de Toxicología del Centro de Investigaciones y Estudios Avanzados,* 

*Laboratorio de Genética. Centro de Investigaciones Regionales. Universidad Autónoma de Yucatán. Mérida, Yucatán,* 

**1. Introduction** 

 \*

*Distrito Federal Mexico* 

