It's In The Genes

Genetic Factors Causing Congenital Heart Defects

Genetic aspects of CHD are an area of intense research and study. Single gene mutations may be causative in familial forms of ASD, MVPS, VSD, congenital heart block, pulmonary hypertension and syndromes like Noonan, LEOPARD, Ellis-van Creveld and Kartagener.

Genes responsible for conditions like Long QT syndrome and Holt Oram syndrome have been mapped. Those likely to cause other conditions including hypertrophic cardiomyopathy, Marfan syndrome and supravalvular AS have been identified.

Chromosome 22 has been implicated in the development of conotruncal malformations.

However, less than 10% of all heart defects can be accounted for by chromosomal and genetic disorders.

Clinical Implications

• Family studies indicate a 2 to 10 fold increase in incidence of CHD in siblings of affected patients, or in offspring of an affected parent.
• Because the incidence in siblings or offspring is only 2 to 10%, it is seldom wise to discourage the parents of an affected child from having additional children if either parent is free from a cardiovascular defect.
• This low possibility, combined with increasing possibilities for effective treatment for most cardiac defects usually justifies a positive approach to family counseling.
• If two or more members of the family are affected, the recurrence risk is high. A pedigree should be obtained and mendelian inheritance patterns figured out before any recommendation can be made.

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