title: Partial trisomy of chromosome no. 1 in two adult brothers due to maternal translocation (1q--;6p+).
abstract: Extra chromosome material on the short arm of chromosome no. 6 (46,XY,6p+) was found in two  mentally retarded adult half-brothers with mildly dysmorphic features. The phenotypically normal mother had a balanced translocation between the long arm of chromosome no. 1 and the short arm of chromosome no. 6:46,XX,t(1;6)(q32;p25). Thus the two affected brothers were trisomic for the long arm segment of chromosome no. 1, distal to q 32. These patients, with mildly dysmorphic features and mental retardation, represent the first cases of partial trisomy 1q surviving to adult-hood. The clinical and cytogenetic data obtained from eight individuals with partial trisomies for different long arm segments of chromosome no. 1 suggest that partial trisomy of the distal two-thirds of the long arm in characterized by severe malformations, growth retardation, and early death. Conversely, partial trisomy for the distal one-third of the long arm is associated with milder malformations and longer survival time as well as growth and mental retardation.
mesh_terms: D000328:Adult; D002900:Chromosomes, Human, 1-3; D002906:Chromosomes, Human, 6-12 and X; D003878:Dermatoglyphics; D005145:Face / Q000002:abnormalities*; D005260:Female; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D007621:Karyotyping; D008297:Male; D010375:Pedigree; D010641:Phenotype; D014178:Translocation, Genetic; D014314:Trisomy