Buccal smears and numerical sex chromosome anomalies.

The results of buccal smear examinations of patients in five institutes for mental retardates, a psychiatric hospital, a home for physically handicapped children, two schools for the deaf, a normal primary school and a newborn nursery are reported. Extra X chromosomes were found in 4/1 000 mentally retarded males, in 1,8/1 000 mentally ill patients and in 1,3/1 000 newborn females. Extra Y chromosomes were found in 1,5/1 000 males, and 3,6/1 000 males were noted to have non-fluorescing Y chromosomes, a normal variant.