A family study of congenital diaphragmatic defects.

The occurrence of specific and nonspecific congenital anomalies was determined in first degree relatives of index patients with congenital diaphragmatic defects who were born in Hungary between 1970 and 1979 and were ascertained through a population-based registry. The cases were grouped into Bochdalek types (N = 156), other types (N = 26), unclassified types (N = 55), and multiple congenital anomalies (MCA) cases including those with congenital diaphragmatic defects (N = 96). The sib occurrence in the Bochdalek type was 0.9% (taking into consideration also the unclassified cases or the total material, it was 0.5% or 0.4%, respectively). Specific familial clusters were not found in other types. Neural tube defects were detected in 1.8% of sibs in the total material and 2.4% in MCA cases.