Cytogenetic analysis of a young woman with gonadal dysgenesis and bilateral gonadoblastoma shared a male karyotype with a rearranged Y chromosome, interpreted as a pericentric inversion. The breakpoints, defined by fluorescent in situ hybridization (FISH), were located on the very distal short arm on band Yp11.31 and in the middle of the Yq12 long arm heterochromatic region. FISH analysis documented that the short arm breakpoint was 93 Kb distal to SRY and disrupted the CD99 gene, which was transposed to the distal portion of Yq12. The proposita's phenotype was similar to that of XY individuals with gonadal dysgenesis but without signs of Ullrich-Turner syndrome. There were no mutations in the SRY gene. Cytogenetic analysis in the proposita's father showed mosaicism of a normal Y chromosome and several different rearrangements, such as deletion of a heterochromatin portion at band Yq12.2, a fragile site at the same band, structural rearrangements between the Y-chromosome and other autosomes, Y-chromosome aneuploidies, and "Premature Centromere Division" (PCD) anomaly. The proposita's inverted Y chromosome appears to have originated from paternal Y chromosome instability. The patient's female phenotype could be due to SRY CpG methylation-mediated positional effects (PEV).
- Pericentric inversion
- Positional variegation effect
- SRY gene
- XY female
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