Patterns of recurrence of congenital heart disease: an analysis of 6,640 consecutive pregnancies evaluated by detailed fetal echocardiography.

<bold>Objectives: </bold>We sought to investigate the pattern of recurrence of congenital heart disease (CHD) where there is one or more affected first-degree relative.<bold>Background: </bold>There are little data on patterns of recurrence of different types of CHD. Analysis of a fetal series allows a high ascertainment of affected cases.<bold>Methods: </bold>We performed an analysis of referrals for detailed fetal echocardiography to a tertiary fetal cardiology unit, where there was a first-degree family history of CHD from 1990 to the end of 1999. Data were entered prospectively on a computerized database. Recurrences were exactly concordant if CHD was identical to the index case, and concordant for the group if belonging to a similar group of CHD.<bold>Results: </bold>A recurrence of CHD was seen in 178 (2.7%) of 6,640 pregnancies. The referral numbers for sibling, maternal, or paternal CHD cases were 5,151, 1,119, and 370, respectively. Exact concordance was seen in 37% of cases (range 0% to 80%), and group concordance was seen in 44%. In families where there were two or more recurrences, the exact concordance rate was 55%. Exact concordance rates were particularly high for isolated atrioventricular septal defects (4 of 5 [80%]) and laterality defects (7 of 11 [64%]).<bold>Conclusions: </bold>The concordance rates of different types of CHD vary widely. Accurate diagnosis of the index case is essential for reliable counseling on patterns of recurrence. Minor CHD in the index case does not exclude more severe disease in recurrences. There appears to be significant under-referral for fetal echocardiography in paternal CHD. [ABSTRACT FROM AUTHOR]