Frequency of consanguinity and its effect on congenital malformation--a hospital based study.

A consecutive sample of 5,000 families of Armed Forces personnel was analysed to study the prevalence of consanguineous marriage and its effect on the prevalence of hereditary gross (physical) malformations. The overall frequency of inbreeding was 76% with a coefficient of 0.04151 which is probably the highest figure reported in literature. The overall prevalence of congenital malformations in children of related parents was 40% (1530 out of 3820) and in non-related parents 26% (305 out of 1180) (p = < 0.01). Considering the prevalence of malformations with the types of relationship of parents, the inter-marriage with first cousins, alone, was highly significant (p = < 0.01).