Sex chromatin and cytogenetic survey of 10417 adult males and 357 children institutionalized in Belgian institutions for mentally retarded patients.

A survey of adult male immates of the major institutions for mental patients in Belgium was undertaken in 1965. Out of 10417 males examined 61 had positive sex chromatin (5.8%); 201 had bilateral small testis (1.9%), 4 hypogonad patients carried a D/D translocation. Out of 857 karyotyped children, 2.9% carried an autosomal or sex-chromosomal anomaly other than trisomy G. This prevalence of chromosomal anomalies in children with low I.Q. (less than 50) emphasizes the need for further studies.