Congenital heart disease occurs in a little less than 1 out of 100 (1%) liveborn children. This number includes all types of heart defects, from small abnormalities that require no intervention to major defects that are life threatening and may require several open heart surgeries. The risk of recurrence in siblings depends on the particular defect and the mode of inheritance involved.
About 20% of congenital heart disease (CHD) can be attributed to known causes such as genetic syndromes, chromosomal anomalies, and teratogens. Examples of these are Down syndrome, Turner syndrome, velocardiofacial syndrome, Noonan syndrome, and drug exposure. In these cases, the recurrence risk of the heart defect is the same as the recurrence risk of the causative factor. It may be very low (most cases of Down syndrome) to very high (if the causative factor is due to a dominant single gene abnormality).
About 80% of CHD is thought to be multifactorial and arises through various combinations of genetic and environmental contributors. In these cases, the recurrence risk in siblings of an affected individual, when neither parent is affected, is in the range of 1%-6%. If more than one sibling is affected, the recurrence risk can increase to 10%. Of note is that the recurrence risk in offspring of affected parents is generally significantly higher than that in siblings of affected individuals with unaffected parents, particularly when the affected parent is the mother.
Recurrence risks also vary considerably among different types of CHD. Obstructive left heart lesions, including hypoplastic left heart syndrome, aortic valve stenosis, and coarctation of the aorta generally have noticeably higher recurrence risks in siblings of unaffected parents and / or offspring of affected parents compared with other types of CHD. It is reported that up to 20% of the asymptomatic first-degree relatives of patients with obstructive left heart lesions may have undiagnosed CHD, in particular bicuspid aortic valve.
In short, if you have a child with a CHD, the risk of having another child with a CHD is higher than that of someone without an affected child, but still quite low. By far and away, you will most likely have a child with a completely normal heart! Having said that, having a child with a CHD is an indication to have a fetal echocardiogram during future pregnancies, and we are happy to perform this screening for you at Pediatric Heart Specialists.
Tracy Laird, M.D.
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