Dicentric Y chromosome arising via tandem translocation.

We describe a 22-year-old woman with primary amenorrhea, bilateral gonadoblastomas, and short stature (148.0 cm), but no other signs of the Ullrich-Turner syndrome. There were three cell lines identified in peripheral blood lymphocytes - 45,X (30%), 46,XY (60%), and 46,X,tan dic(Y) (10%). Cells cultured from gonadal biopsies showed only the 45,X karyotype. However, frozen sections of the biopsies showed frequent single and rare double-Y-chromatin bodies. Lymphocytes were H-Y antigen-negative. This previously undescribed structurally abnormal chromosome probably consists of two Y chromosomes attached end-to-end in a tandem translocation. One of the centromeres forms the primary (functional) constriction, the other being detectable only as C-positive material on each chromatid, so presumably inactive. The discrepancy between the presence of Y-chromatin in frozen sections of the gonads and its absence from karyotype in gonadal cultures is indicative of cell selection in tissue culture. Finally, the case confirms the high risk of gonadoblastoma in women with a Y chromosome, even in the absence of H-Y antigen.