title: Investigations of families with two or more mentally defective siblings. III. Chromosome studies.
mesh_terms: D000293:Adolescent; D000328:Adult; D002869:Chromosome Aberrations / Q000235:genetics*; D025063:Chromosome Disorders; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D012307:Risk Factors