In a female patient with dextrocardia and unbalanced atrioventricular septal defect, we identified compound heterozygous missense variants in DNAH9, a gene recently associated with laterality defects.22 Both variants p.(Asp1474Gly) and (Ile4415Thr) were rare and predicted to be damaging. Here, DNAH9 is linked to familial atrioventricular septal defect.