Two cases of an abnormal short arm of chromosome 8 (8p+) associated with mental retardation.

Morphologically similar chromosome anomalies, 8p+, were found in two inmates of an institution for the mentally retarded. Analysis of the G-and R-banding patterns showed that the first subject had a duplication of region p2 of chromosome 8; the second subject had an insertion of an unidentified chromosome segment at 8p11. Both subjects were severely mentally retarded. The physical malformations were more severe in the second subject than in the first, who had only minor signs. The dermatoglyphics are recorded.