Genetic Study on the Etiology of Congenital Heart Diseases

The etiology of congenital heart disease was studied in 1,076 patients who were diagnosed in our outpatient clinic from September 1, 198 1 to February 29, 1984. In these patients, 9(0.8%) had single gene disorders and 63(5.9%) had chromosomal aberrations, of which 55(87.7%) were Down syndrome. The number of patients who had congenital heart diseases due to environmental insult was 2(0.2%), and those with a malformation syndrome of unknown etiology were 6(0.6%). The etiology of congenital heart diseases in the remaining 996 patients (92.6%) was not clarified. In these cases, the rates of consanguinity of parents, and paternal and maternal grandparents, the ages of the parents when the patients were born, and the number of minor anomalies, were compared with those in normal controls. The complications of major anomalies were also investigated. Further, the recurrence risks in patients' siblings were also calculated.