A CASE WITH MOSAIC DICENTRIC, TETRACENTRIC, AND OCTACENTRIC RING Y CHROMOSOMES

A newborn female infant presented with abnormalities of the external g enitalia including a 3 x 1 cm phallic structure, a perineal urethral o pening, bifid scrotum, and a single urogenital opening. Peripheral blo od karyotype was 45,X[81]/46,X,+r(Y)[19], however, there were no signs of Ullrich-Turner syndrome. High resolution G-banding as well as C-an d Q-banding did not demonstrate any specific banding pattern or presen ce of heterochromatin on the ring. However, it was noticed that some o f the rings were larger than others. FISH with a probe for Yq12 was ne gative in all metaphases studied. A Y-specific paint probe hybridized to the entire ring chromosome, confirming its origin. PCR analysis sho wed the presence of the SRY locus and of proximal Yq locus DYS271. Tri ple color FISH with probes for the Y centromere, DYZ5 (Yp), and all hu man telomeres showed the existence of different types of rings, some d icentric, some tetracentric, and some probably octacentric. Owing to t he increased risk for gonadoblastoma, a surgical removal of the gonads was performed. (C) 1997 Wiley-Liss, Inc.