Genetic Counseling

Overview: Genetic Counseling

According to the National Society of Genetic Counselors, genetic counseling is the process of helping people understand and adapt to the medical, psychological, and familial implications of the genetic contribution to disease. This process integrates (1) interpretation of familial and medical histories to assess the chance of disease occurrence or recurrence; (2) education about inheritance, testing management, prevention, resources, and research; and (3) counseling to promote informed choices of adaptation to the risk or condition.

Genetic counseling involves numerous steps:

• 1.

  Validating the maternal diagnosis

• 2.

  Evaluating the needs of the counselee

• 3.

  Evaluating the family history

• 4.

  Estimating the risk

• 5.

  Communicating the risk to the counselee

• 6.

  Making a decision and taking appropriate action

• 7.

  Following up with the family.

In addition, if the patient has a limited life expectancy, the ethical aspects of parenthood should be discussed.

The source of payment for genetic counseling is problematic because it is often not covered by insurance.

Risk Assessment

It is standard to provide a figure for the risk of recurrence of genetic conditions. Risk calculation may be based on known genetic inheritance patterns (e.g., autosomal dominant, in which case the risk to the child of inheriting the trait is 50%) or empiric risk factors based on observed patterns of inheritance, depending on the disorder. Only about 3% of congenital heart diseases follow Mendelian inheritance patterns, and it is estimated that 90% of cases are of unknown genetic cause.

Most women with congenital heart disease seeking genetic counseling have conditions for which the genetics are not completely worked out and a precise risk is unknown. Interestingly, it seems that the risk of having a child with congenital heart disease seems to be greater if the mother is affected than if the father is affected, but the reason for this is unknown.

In general, the risk of any woman having a child with congenital heart disease is 0.5% to 1.0%. The risk goes up to 5% if the mother is affected, and 2% to 3% if the father is affected. If a sibling is affected, the risk is 2% to 3%. If two siblings are affected, it goes up to 10%, and if more than three first-degree relatives are affected, it is greater than 50% ( Table 33.1 ).

Next we discuss genetic disorders involving the heart that follow a Mendelian inheritance pattern. Disorders are presented in alphabetical order.

Ellis-Van Creveld Syndrome

Ellis-van Creveld syndrome, or chondroectodermal dysplasia, manifests as a large atrial septal defect associated with postaxial polydactyly, short-limbed dwarfism, and dysplastic nails. It is autosomal recessive.