Pericentromeric structure of human X "isochromosomes": evidence for molecular heterogeneity.
Three different long-arm X isochromosomes and an isodicentric X chromosome were examined by in situ hybridization with X-chromosome-specific alpha-satellite probes and by quantitation of Southern blots hybridized with proximal short-arm probes. Each chromosome had a unique pericentromeric structure. The isodicentric X chromosome was clearly dicentric, showing two distinct alpha-satellite hybridization signals and duplication of short-arm material. Two isochromosomes showed a larger than normal, bifid alpha-satellite signal and also had duplications of different extents of short-arm material. The third X isochromosome could not be distinguished from a classical long-arm isochromosome; it did not have a short-arm duplication and it had a single alpha-satellite signal. These data indicate that rearrangements responsible for X isochromosome formation can occur at numerous locations in the pericentromeric region and that some X isochromosomes may involve duplications of substantial portions of the short arm.
Department of Medical Genetics, University of Toronto, Ontario, Canada.
C B
CB
Sharp
H M
HM
Bedford
H F
HF
Willard
D001710:Biotin; D015139:Blotting, Southern; D002460:Cell Line; D002869:Chromosome Aberrations / Q000235:genetics*; D002874:Chromosome Mapping; D015342:DNA Probes; D004276:DNA, Satellite / Q000235:genetics*; D006801:Humans; D009693:Nucleic Acid Hybridization; D014424:Turner Syndrome / Q000235:genetics; D014960:X Chromosome / Q000648:ultrastructure
D015342:DNA Probes; D004276:DNA, Satellite; D001710:Biotin