[Cytogenetic study of a recent case of trisomy 12p].

A case of trisomy for the short arm and a part of the long arm of chromosome 12 is reported. Before the pregnancy sterility was noted during several years. Birth weight was normal; the newborn with multiple congenital defects died before the 4th day. Her mother, grandmother, and two brothers of the latter showed a balanced translocation t (5 ; 12) (p15 ; q132). The affected child inherited the derived 12 as a 47th chromosome.