*3.2.3.1. Karyotype*

interventional techniques shortly after birth. The primary focus of treatment of the patient with cardiac malformation is diagnosis and best course of treatment. However an important and integral part of the care of these patients is to have genetic counseling with their parents in regards to possible etiologies of the congenital heart disease. In the past, it was believed that the recurrence of congenital cardiovascular malformations in the same family was low, with expert quoting recurrence rate of only 3–5%. However currently it is known that for a family with autosomal-dominant 22q 11 deletion syndrome, the risk is up to 50%

Etiology of some cardiac malformation that are known to have genetic components, where they make up approximately 5–17% are part of a genetic syndrome. Environmental factors need to be considered and a detailed family history needs to be elicited [119]. The role of the primary care giver is paramount, in detecting possible associated cardiac genetic syndromes. When genetic syndromes are a possibility, intervention requires referral to a genetic counselor for accurate diagnosis and possible future pregnancy. Since approximately, 75% of currently known cardiac malformations have no identifiable cause or underlying condition, the necessity for genetic counseling may appear unwarranted. However with the advent of advanced genetic testing such as whole exome sequencing, once unrecognized features are now being associated with syndromes [120–123]. Postnatal, the purpose of the genetic evaluation is to help establish a diagnosis and educate the family about future risk recurrence and expected outcomes. Parents need to be counseled and educated on both the numeric risk and

The role of genetic evaluation in patients with cardiac malformations, as patients live longer is becoming increasingly important. In the past, where genetic testing was limited to research laboratories, in today clinical practice this is no longer the case. The current clinical practice allows for the physician to obtain chromosomal analysis and request FISH testing when looking for specific deletions [22, 121–123]. The yields of these testing becomes higher when a genetic counselor is consulted prior to obtaining specific test. However even with the advancement on genetic testing, not all patients with congenital heart disease will be identified to have a genetic cause. The recommend approach for newly diagnosed patients with cardiac malformations includes the routine evaluation of all available relatives for a potential genetic contribution [22], and obtaining an accurate and complete medical history and documenting and extended pedigree. If from the information a syndrome if recognized, then evaluation and counseling of other family members becomes extremely important. Depending on the suspected diagnosis or syndrome, other consultation will need to be obtained such

Cytogenetic testing should be obtained in the following situations (from AHA Scientific

**1.** Any child or infant with the phenotype of a recognizable chromosomal syndrome (e.g.,

with a variable phenotypic expression [117, 118].

424 Congenital Anomalies - From the Embryo to the Neonate

the variable expressivity that makes predicting severity difficult.

*3.2.2. Genetic evaluation of congenital heart disease*

neurology, ophthalmology, and others subspecialties.

Statement):

Trisomy 21 or 18)

Prior to the advent of advanced cytogenetic testing, the standard chromosomal analysis (i.e., karyotype) was widely used. Chromosome testing using standard metaphase karyotype is the traditional method and remains standard for the detection of aneuploidy (Trisomy 13, 18 and 21 and Turners 45 XO) and detecting gross changes such translocation and duplications [22, 117, 125]. A more sensitive karyotype is also available, which allows for the visualizations of greater number of bands. However, standard karyotype has an estimated 3% detection rate for pathogenic chromosome abnormalities. Conventional chromosome analysis detects wellknown chromosome aneuploidies in about 10% of cases of CHDs [126]. with the advent and feasibility of newer technology, karyotype maybe used less and become replaced.
