A 9p13-->p24 duplication coupled with a whole 22q translocation onto 9p24.
We report on a 3-year-old girl with a typical 9p trisomy syndrome, whose 45-chromosome karyotype includes a 9p+. As assessed by G, C and Ag-NOR bands, the rearranged chromosome resulted from a 9p13-->p24 direct duplication coupled with a translocation of the whole 22q onto 9pter, had heterochromatin at the junction site, lacked both nucleolar organizing regions (NORs) and centromere dots at the unconstricted fusion point, and was present in all metaphases scored. FISH results: a 9p subtelomere probe gave a diminished signal on the 9p+ precisely at the duplication junction 9p24::9p13, but no labeling was observed at the 9;22 translocation site; a pancentromeric alphoid probe labeled all centromeres, and gave a distinct signal at the 9pter;22cen junction. Hence, her karyotype was 45,XX,rea(9;22)(9qter-->9p24::9p13-->9p24::22p10-->22qter).ish rea(9;22) (9psubtel+dim,pancen+). Parental chromosomes were normal. The distinctiveness of the present centromere-telomere fusion rests on the coupling of an intrachromosomal distal duplication with a whole-arm translocation including alphoid DNA onto the duplicated segment. The centromeric inertia of the residual alphoid DNA in the present case compares with the variable functional status of the chromosome 22 centromere in true heterodicentrics involving such a chromosome.
Rivera
Horacio
H
Centro de Investigación Biomédica de Occidente, IMSS, Ap. Postal 1-3838, Guadalajara, Jal., Mexico. hrivera@encar.udg.mx
Vásquez-Velásquez
Ana I
AI
Ramirez-Duenas
Mariá de Lourdes
Mde L
Becerra-Solano
Luis Eduardo
LE
D000015:Abnormalities, Multiple / Q000235:genetics; D000782:Aneuploidy; D002503:Centromere / Q000235:genetics; D002675:Child, Preschool; D002871:Chromosome Banding; D002892:Chromosomes, Human, Pair 22; D002899:Chromosomes, Human, Pair 9; D005260:Female; D006570:Heterochromatin / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D000091402:Prohibitins; D013577:Syndrome; D016615:Telomere / Q000235:genetics; D014178:Translocation, Genetic
D006570:Heterochromatin; C000717331:PHB2 protein, human; D000091402:Prohibitins