The familial incidence of congenital malformation of the heart.

It is generally believed that the incidence of congenital malformation of the heart is raised in relatives of affected individuals. The evidence in support of this view consists mainly of isolated records of families with more than one affected member (Courter et al., 1948, refer to 63 reported cases), but a few examples have been noted in the course of investigations of large series of patients (for example, by Abbott, 1927; Dogramaci and Green, 1947; Campbell, 1949; and Lamy and Schweisguth, 1950, among others). Such observations are suggestive, but scarcely justify a confident assertion that incidence in relatives is raised, since both the numbers of relatives at risk and the incidence of affected in the related general populations were unknown. In the present communication we give the numbers of affected and unaffected relatives of a series of patients with various congenital cardiac malformations. All known affected relatives were recorded during the enquiry, but observations on incidence are restricted to brothers, sisters, parents, and first cousins of propositi. The data suggest that incidence of congenital malformation of the heart is raised in sibs, but is not raised in parents and cousins of affected individuals.