Influence of consanguinity on the pattern of familial aggregation of congenital cardiovascular anomalies in an outpatient population: studies from the eastern province of Saudi Arabia.

Background: Familial aggregation of congenital heart disease (CHD) has been well described in different populations, in particular those with a high consanguinity rate. Extensive genetic study of affected families has improved the understanding of basic genetics of different cardiac lesions.

Objective: To identify the role of consanguinity as a risk factor among familial cases of CHD in a stable outpatient population of a tertiary care center in the Eastern Province of Saudi Arabia.

Methods: All familial cases of CHD seen over 5 years (1996-2000) in the Division of Pediatric Cardiology were identified. The presence or absence of parental consanguinity (first cousin marriage) was defined in each of these families.

Results: Ninety-three cases were identified in 37 families. Twenty-three (62%) families resulted from consanguineous marriages. In 4 families where there were 2 marriages, the affected children came from the consanguineous marriage in 3 of these families. Discordant lesions occur only among non-consanguineous cases, while all consanguineous cases were concordant. Five sets of twins of the same sex (one set are monozygotic by DNA analysis) occurred among consanguineous marriages, in 3 of these both twins were affected with the same disease. Affected parents were seen in 2 families with consanguineous marriage and none in the non-consanguineous marriages. The prevalence of dilated cardiomyopathy was much higher among consanguineous cases (26 vs. 2).

Conclusions: Familial aggregation of congenital heart disease is common in our population. Consanguinity is common in these families, and the distribution of congenital heart disease differs in this subgroup compared to the rest of the familial cases. Further genetic studies of these families may help to shed more light on basic genetics and the specific pathogenetic mechanisms involved.