FISH characterization of a dicentric Yq (p11.32) isochromosome in an azoospermic male

The most common structural rearrangements of the Y chromosome result in the production of dicentrics. In this work, we analyze an abnormal Y chromosome, detected as a mosaic in an azoospermic male ascertained for infertility. FISH with seven different DNA probes specific for Y chromosome sequences (Y alpha-satellite, Y alpha-satellite 111, non-alpha-satellite centromeric Y, SRY gene, subtelomeric Yp, subtelomeric Yq, and PNA-tel) and CGH analysis were performed. FISH results showed that the abnormal Y chromosome was a dicentric Yq isochromosome and that the breakpoint was distally in band Yp11.32. Lymphocyte chromosomes showed a mosaicism. with 46,X,idicY(qter--> p11.32::p11.32-->qter) (51.7%), 46,X-Y (45.6%), and other cell lines (2.7%). In oral interphase cells, the mosaicism. was 46,XidicY (62.8%), 46,X-Y (25.7%), 45,X (6.6%), and others (4.9%). The possible origin of this dicentric Yq isochromosome is discussed. Finally, we compare differences in mosaicism. and phenotype among three reported cases with the breakpoint at Yp11.32 (C) 2004 Wiley-Liss, Inc.