Chromosome studies in patients with congenital malformations and mental retardation.

16 (41%) out of 39 individuals referred by physicians because of sexual anomalies showed abnormal karyotypes; the corresponding figure for those investigated due to suspected autosomal aberrations was 37 out of 104 (36%). A special survey was also conducted among 51 mentally defective children with at least 3 malformations; 5 individuals (10%) were observed with chromosome abnormalities plus 3(6%) with rare variants. These results were compared with those presented in 26 other surveys reported in the literature.