[Mechanisms common to the development of malformation in congenital and sporadic forms of atrial septal defect (type II) (author's transl)].

Familial prevalence of some congenital cardiopathies leads to the conclusion that genetic factors might be involved. The case histories are presented of three families with atrial septal defect, Type II (ASD II) in which autosomal dominant inheritance was assumed on account of the pedigree analysis. Each family member was examined serologically, morphologically and morphometrically. One family was also tested for cytogenetic abnormalities. It is highly probable that the gene responsible for the defect is linked to the HLA system (Lod score = + 3.612) and is, therefore, located on the short arm of chromosome 6. The morphological examinations demonstrated uniformity of individual ear traits in related patients; moreover, the palmar dermatoglyphics showed a tendency to shortening of main line C, to ulnar and distal shifting of the carpal triradius and to an increase in hypothenar patterns. In addition a study was carried out of patients with apparently sporadic cardiopathy. A similar trend as to palmar configuration was observed. An attempt was made to connect known factors causing malformations with the results of this investigations.