Risk of congenital heart defects in relatives of patients with atrioventricular canal

Objective.--To investigate the overall occurrence of congenital heart disease in 103 pedigrees with a proband affected with atrioventricular canal. Design.--Family study of patient series. Setting.--Department of Pediatric Cardiology, Bambino Gesu Hospital, Rome, Italy. Participants.--One hundred three consecutive patients with atrioventricular canal and normal karyotype and their first- and second-degree relatives. Interventions.--None. Measurements/Main Results.--In 12 pedigrees (11.7%), one or more relatives had concordant or discordant congenital heart disease. Congenital heart disease occurred in four (1.9%) of the 206 parents of probands, in four (3.6%) of the 111 siblings, and in five (0.8%) of the 644 uncles or aunts. None of the grandparents had congenital heart disease. Atrioventricular canal affected several family members in five pedigrees. Conclusions.--Familial aggregation of atrioventricular canal in several pedigrees requires careful collection of family histories, accurate cardiologic evaluation of the first-and second-degree relatives of the probands, and fetal echocardiography in all pregnant women in at-risk families. (AJDC. 1993;147:1295-1297)
Children of parents with atrioventricular canal (AVC) may have an increased risk of having AVC, especially if the affected parent is the mother. AVC is a birth defect involving a gap between the heart septa. AVC may be an inherited condition, possibly associated with a major gene. Researchers studied families of 103 patients with AVC between the ages of 3 months and 28 years to determine the occurrence of congenital heart disease. Of 317 parents and siblings, 2.5% had a congenital heart disease. Three of the four parents and two of the four siblings with congenital heart disease had AVC. Almost 12% of the 103 patients with AVC had at least one relative with congenital heart disease. In five of the families affected by congenital heart disease, most of the family members had AVC. Molecular analysis of affected family members has not revealed the genetic involvement. Close relatives of patients with AVC should be evaluated for heart defects and receive prenatal counseling on their children's risk of AVC.