title: Dissociation of a t(12;21) resulting in a normal cell line in two trisomic 21 sons of a nonmosaic t(12;21) father?
abstract: A normal cell line arising from a translocation, t(12;21), possibly by dissociation, was observed in two brothers in early life. Each was conceived as trisomic 21 by their 45,XY,-12,-21,+t(12;21) father, who was phenotypically normal. Each brother showed morphologic manifestations of trisomy 21 syndrome, and each was mildly mentally retarded. Dermatoglyphic indices were not diagnostic of trisomy 21 syndrome. At 4 months the younger brother had a 50:50 proportion of trisomic:normal blood cells which became 25:75 of trisomic 21:normal at 36 months. The older brother had a 25:75 proportion of trisomic 21:normal when first studied at 41/2 years. A similar t(12;21) has not previously been reported. The occurrence of an apparently normal cell line arising spontaneously is unique.
mesh_terms: D000328:Adult; D002460:Cell Line; D002675:Child, Preschool; D002871:Chromosome Banding; D002904:Chromosomes, Human, 21-22 and Y; D002906:Chromosomes, Human, 6-12 and X; D003878:Dermatoglyphics; D004314:Down Syndrome / Q000235:genetics*; D006801:Humans; D007223:Infant; D007621:Karyotyping; D008297:Male; D009030:Mosaicism; D010375:Pedigree; D010641:Phenotype; D014178:Translocation, Genetic