*4.2.2 Steroid synthesis defects – overproduction of androgens*

Steroid synthesis defects leading to congenital adrenal hyperplasia with androgen excess cause clitoral enlargement, partial or complete fusion of the labia majora and a short vagina [26] with virilization Prader stage above III [55].

The most common cause of 46, XX disorders of sexual differentiation (**Figure 6**) is 21-hydroxylase (21-OH) deficiency. This occurs in 90% of cases [55] and has a prevalence of 1:14,000–1:15,000 worldwide [54, 55]. This autosomal recessive condition is caused by mutations in the 21-OH gene (*CYP21A2*) on chromosome 6p21.1. The severity of the disease correlates generally to the degree of enzyme activity with classic 21(OH) deficiency having less than 5% activity. These patients present with congenital adrenal hyperplasia and in utero virilization of the external genitalia in females. Non-classic 21(OH) deficiency have >15% residual activity. These patients present with androgen excess in adolescence and early adulthood [54].

Patients with classic 21(OH) deficiency are at high risk (approximately 70%) for neonatal salt wasting [17]. These patients present with high 17α-hydroxyprogesterone, androstenedione and testosterone levels (**Figure 6**) and decreased sodium, elevated potassium and elevated renin at the end of the first week of life [17]. The high androgens levels result in virilization of the female external genitalia in female fetuses. This can be seen as early as 12 weeks gestation [54] and varies from mild clitoromegaly to complete male external genitalia with rugated and pigmented labioscrotal folds and a phallic structure [17].

Non-classic 21(OH) deficiency is more common than the classic form. The world wide incidence is 1:300, the Ashkenazi Jewish population has a higher incidence described as 1:27 [54]. They generally present in adolescence with a presentation is similar to Polycystic Ovarian Syndrome, namely premature pubarche, acne, hirsutism and irregular menses.

11β-OH is present in the adrenals and coded by the CYP11B1 gene. Defects lead to congenital adrenal hyperplasia which present with a similar picture to classical CAH. This is the second most common cause of congenital adrenal hyperplasia

with an incidence of less than 1:100,000 births. The condition is inherited in an autosomal recessive manner and homozygote or compound heterozygote mutations in the *CYP11B1* gene (mapped to chromosome 8q21-q22) results in a loss of enzyme function [54]. The most common mutation in the CYP11B1 gene is the R448H mutation, which is also the founder mutation identified in Moroccan Jews who has a high prevalence of the condition [54]. Patients with 11β-OH deficiency present with virilization of the external genitalia due androgen excess; biochemically this is seen as elevated 11-deoxycortisol and 17α-hydroxypregnelone (**Figure 6**) [17]. These patients have normal aldosterone production and thus a decreased risk of salt wasting. Aldosterone synthesis is mediated by the *CYP11B2* gene, which is homologous to *CYP11B1* and located within 40 kb [54]. This results in normal levels of deoxycorticosterone and aldosterone and a wide range of blood pressure phenotypes have been reported [26, 54].

There are rare forms of defects in steroid synthesis causing CAH. These include 3β-hydroxysteroid dehydrogenase (3β-HSD) deficiency and 11β-hydroxylase (11β-OH) deficiency. There are two enzymes that mediate 3β-HSD. The type 1 enzyme (*HSD3B1*) is present in the skin, liver, peripheral tissues and placenta and the high levels of dehydroepiandrosterone are converted to androstenedione and then to testosterone and DHT [54]. The degree of virilization is moderate compared to 21-OH deficiency. Patients present with mild to moderate clitoromegaly and rarely fusion of the labioscrotal folds (**Figures 5** and **6**) [54, 55].

Type 2 (*HSD3B2*) deficiency is a rare condition occurring in 1:1,000,000 births. This condition presents with severe salt wasting similar to 21-OH deficiency and less severe virilization [54, 55]. This is an autosomal recessive condition caused by mutations in the *HSD3B2* gene, located on chromosome 1p13. As with other forms of CAH, the severity of the disease correlates with the degree of enzyme activity [54, 55]. Type 2 deficiency leads to impaired aldosterone and cortisol production presenting biochemically with elevated pregnenolone, 17(OH) pregnenolone and elevated dehydroepiandrosterone (**Figure 6**) [17, 55]. This leads to salt wasting, hyperkalemia and volume depletion similar to 21(OH) deficiency. Virilization occurs in a similar fashion to 11β (OH) deficiency.

#### **5. Investigations**

The initial investigation should include a careful physical examination to determine if the presentation is isolated or non-isolated (**Figure 1**). In view of the association between IUGR and undervirilization in chromosomal male fetuses, results of maternal serum screening, placental growth factor and detailed fetal ultrasound findings and biophysical profile as well as the birth weight should be obtained.

Examination of the external genitalia should include:


**73**

labia majora.

of life.

*Approach to the Newborn with Disorders of Sex Development*

openings and then compared to the Prader scale [57]. Investigations should be targeted to identify:

c.Location, structure and volume of the gonads—gonads located in the inguinal canal and labioscrotal folds are always testes although ovotestes is also a

The perineum should also be examined for the number and position of the

3.The internal genitalia [using ultrasound and/or MRI to find if], is there is a

Since gonads in the inguinal canal and labioscrotal folds are almost always testis finding them on palpation usually indicates the existence of the SRY gene. However, the chromosome sex should be determined using quantitative fluorescent PCR (QF-PCR) or fluorescent in-situ hybridization (FISH) analysis. Microarray analysis should be completed, looking for submicroscopic deletion or duplication involving

Unique situations to be aware of include the most severe cases (46,XY with complete feminization and 46,XX with complete masculinization) it is difficult to diagnose an abnormal phenotype. Other scenarios include isolated grade 1 (glandular) and 2 (penile shaft) hypospadias, especially when associated with intrauterine growth restriction (IUGR) the investigative yield is low. Most cases are the result of the IUGR – Placental dysfunction – abnormal genitalia syndrome [59]; however, since this is a diagnosis by exclusion and there is no objective way of differentiating the condition from PAIS and mild 5α reductase deficiency, DNA analysis using 46,XY panel or for these conditions is recommended. Further investigations are also indicated with hypospadias associated with bilateral or unilateral undescended testes, micropenis, clitoromegaly, posterior fusion of the

The most common cause of abnormal genitalia in female is CAH. When initial investigations show XX karyotype, 17-hydroxyprogesterone (17-OH) and renin at 48 hours of age (after the surge of adrenal hormones at birth) should be done. The abnormal sodium and potassium blood levels will present only in the second week

In cases with XY karyotype, the testosterone, LH and FSH levels should be measured looking for low testosterone and dihydrotestosterone (DHT) levels. Answering the above four questions will guide further investigations which include assessment of adrenal function, testicular function and internal genitalia using

Genetic testing plays an important role in finding the etiology and thus providing genetic counselling regarding the recurrence risks and the prenatal/preimplantation options in future pregnancies. The use of DSD genetic panels can investigate multiple genes simultaneously and accelerate the diagnostic process. Using massive parallel sequencing looking at a variety of genes causing DSD in a cohort of 278 patients with 46, XY DSD and 48 with 46, XX DSD of an unknown etiology, Eggers et al., found a likely genetic diagnosis in 43% of patients with 46, XY DSD and 17% of patients with 46, XX DSD [60]. If no gene mutation is identified, whole exome/

ultrasound, MRI and/or genitogram or laparoscopy [17].

genome sequencing is recommended.

uterus, is the uterus normal and are there intrabdominal gonads

the *SRY* gene as well as other chromosome abnormalities [58].

*DOI: http://dx.doi.org/10.5772/intechopen.94570*

possibility.

1.The chromosome sex

4.The external genitalia

2.The gonadal sex

c.Location, structure and volume of the gonads—gonads located in the inguinal canal and labioscrotal folds are always testes although ovotestes is also a possibility.

The perineum should also be examined for the number and position of the openings and then compared to the Prader scale [57]. Investigations should be targeted to identify:


*Congenital Anomalies in Newborn Infants - Clinical and Etiopathological Perspectives*

been reported [26, 54].

**5. Investigations**

with an incidence of less than 1:100,000 births. The condition is inherited in an autosomal recessive manner and homozygote or compound heterozygote mutations in the *CYP11B1* gene (mapped to chromosome 8q21-q22) results in a loss of enzyme function [54]. The most common mutation in the CYP11B1 gene is the R448H mutation, which is also the founder mutation identified in Moroccan Jews who has a high prevalence of the condition [54]. Patients with 11β-OH deficiency present with virilization of the external genitalia due androgen excess; biochemically this is seen as elevated 11-deoxycortisol and 17α-hydroxypregnelone (**Figure 6**) [17]. These patients have normal aldosterone production and thus a decreased risk of salt wasting. Aldosterone synthesis is mediated by the *CYP11B2* gene, which is homologous to *CYP11B1* and located within 40 kb [54]. This results in normal levels of deoxycorticosterone and aldosterone and a wide range of blood pressure phenotypes have

There are rare forms of defects in steroid synthesis causing CAH. These include

Type 2 (*HSD3B2*) deficiency is a rare condition occurring in 1:1,000,000 births. This condition presents with severe salt wasting similar to 21-OH deficiency and less severe virilization [54, 55]. This is an autosomal recessive condition caused by mutations in the *HSD3B2* gene, located on chromosome 1p13. As with other forms of CAH, the severity of the disease correlates with the degree of enzyme activity [54, 55]. Type 2 deficiency leads to impaired aldosterone and cortisol production presenting biochemically with elevated pregnenolone, 17(OH) pregnenolone and elevated dehydroepiandrosterone (**Figure 6**) [17, 55]. This leads to salt wasting, hyperkalemia and volume depletion similar to 21(OH) deficiency. Virilization

The initial investigation should include a careful physical examination to determine if the presentation is isolated or non-isolated (**Figure 1**). In view of the association between IUGR and undervirilization in chromosomal male fetuses, results of maternal serum screening, placental growth factor and detailed fetal ultrasound findings and biophysical profile as well as the birth weight should be obtained.

a.Assessment of the labioscrotal folds—the labioscrotal folds should be

assessed for pigmentation, rugation, asymmetry and fusion. High insertion of the labioscrotal folds (above the penis) as well as "buried penis" should be

b.Assessment of the phallic structure, the length, breadth, urogenital openings—the phallic structure should be assessed for length, breadth, chordee and relationship with the labioscrotal folds looking for complete or incomplete penoscrotal transposition. The normal penile length at term is 3.5 cm with 2.5 cm being at −2SD. The normal clitoral length at term is 2–8.5 mm and

3β-hydroxysteroid dehydrogenase (3β-HSD) deficiency and 11β-hydroxylase (11β-OH) deficiency. There are two enzymes that mediate 3β-HSD. The type 1 enzyme (*HSD3B1*) is present in the skin, liver, peripheral tissues and placenta and the high levels of dehydroepiandrosterone are converted to androstenedione and then to testosterone and DHT [54]. The degree of virilization is moderate compared to 21-OH deficiency. Patients present with mild to moderate clitoromegaly and

rarely fusion of the labioscrotal folds (**Figures 5** and **6**) [54, 55].

occurs in a similar fashion to 11β (OH) deficiency.

Examination of the external genitalia should include:

differentiated from micropenis.

breadth 2–6 mm [56].

**72**


Since gonads in the inguinal canal and labioscrotal folds are almost always testis finding them on palpation usually indicates the existence of the SRY gene. However, the chromosome sex should be determined using quantitative fluorescent PCR (QF-PCR) or fluorescent in-situ hybridization (FISH) analysis. Microarray analysis should be completed, looking for submicroscopic deletion or duplication involving the *SRY* gene as well as other chromosome abnormalities [58].

Unique situations to be aware of include the most severe cases (46,XY with complete feminization and 46,XX with complete masculinization) it is difficult to diagnose an abnormal phenotype. Other scenarios include isolated grade 1 (glandular) and 2 (penile shaft) hypospadias, especially when associated with intrauterine growth restriction (IUGR) the investigative yield is low. Most cases are the result of the IUGR – Placental dysfunction – abnormal genitalia syndrome [59]; however, since this is a diagnosis by exclusion and there is no objective way of differentiating the condition from PAIS and mild 5α reductase deficiency, DNA analysis using 46,XY panel or for these conditions is recommended. Further investigations are also indicated with hypospadias associated with bilateral or unilateral undescended testes, micropenis, clitoromegaly, posterior fusion of the labia majora.

The most common cause of abnormal genitalia in female is CAH. When initial investigations show XX karyotype, 17-hydroxyprogesterone (17-OH) and renin at 48 hours of age (after the surge of adrenal hormones at birth) should be done. The abnormal sodium and potassium blood levels will present only in the second week of life.

In cases with XY karyotype, the testosterone, LH and FSH levels should be measured looking for low testosterone and dihydrotestosterone (DHT) levels. Answering the above four questions will guide further investigations which include assessment of adrenal function, testicular function and internal genitalia using ultrasound, MRI and/or genitogram or laparoscopy [17].

Genetic testing plays an important role in finding the etiology and thus providing genetic counselling regarding the recurrence risks and the prenatal/preimplantation options in future pregnancies. The use of DSD genetic panels can investigate multiple genes simultaneously and accelerate the diagnostic process. Using massive parallel sequencing looking at a variety of genes causing DSD in a cohort of 278 patients with 46, XY DSD and 48 with 46, XX DSD of an unknown etiology, Eggers et al., found a likely genetic diagnosis in 43% of patients with 46, XY DSD and 17% of patients with 46, XX DSD [60]. If no gene mutation is identified, whole exome/ genome sequencing is recommended.
