title: Two cases of trisomy 21 and one XXY case with atypical clinical features.
abstract: Three patients with mental retardation and multiple congenital abnormalities are described. Although their clinical appearance was not suggestive of Down's syndrome, chromosome studies showed a non-disjunctional trisomy 21 in two of the patients. The third case had an unsuspected XXY karyotype.
mesh_terms: D000015:Abnormalities, Multiple / Q000175:diagnosis; D000293:Adolescent; D000328:Adult; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000175:diagnosis; D007621:Karyotyping; D007713:Klinefelter Syndrome / Q000175:diagnosis*; D008297:Male; D010641:Phenotype