Molecular cytogenetic evidence for amplification of chromosome-specific alphoid sequences at enlarged C-bands on chromosome 6.
We have characterized variant centromeric regions of chromosome 6 segregating in two families. The heteromorphism, 6ph+, stains negatively with G- and Q-banding and darkly with C-banding. The variant C-band regions measure two to three times the length of their homologues. The centromeric regions of the variant chromosome 6 and its homologue are not significantly elongated by adding 5-azacytidine to culture. We determined that the amount of the alphoid centromeric repeat 308 (DZ61), which is chromosome 6 specific, is amplified two- to threefold in the genomes of individuals with the 6ph+ variants. In situ hybridization localized the increase in 308 repeats to the 6ph+ region. These results suggest an association between amplification of chromosome-specific alphoid sequences and enlargement of specific C-band regions.
Jabs
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EW
Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
Carpenter
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D002503:Centromere; D002871:Chromosome Banding; D002896:Chromosomes, Human, Pair 6; D004276:DNA, Satellite / Q000235:genetics*; D005784:Gene Amplification; D005819:Genetic Markers; D006801:Humans; D007621:Karyotyping; D012091:Repetitive Sequences, Nucleic Acid
D004276:DNA, Satellite; D005819:Genetic Markers