Detailed analysis of isodicentric Y in a case with azoospermia and 45,x/46,x,idic(Y) mosaicism.

Isodicentric chromosomes are the most commonly reported aberrations of the human Y chromosome. We characterized the isodicentric Y chromosome from an azoospermic male by fluorescence in situ hybridization (FISH) and PCR. The patient was a 33-year-old man who visited our hospital for evaluation of infertility. He expressed male external genitalia and showed normal testosterone levels. However, severe varicocele on both sides and hydrocele of the right side were found upon ultrasonography of the scrotum, and no sperm were found on semen analysis. The patient showed 46,X,idic(Y)(q11.22)[58]/45,X[12] karyotype. FISH demonstrated the presence of two centromeres and two SRY regions (74.0% of cells counted). PCR showed the breakpoint between SY161 and SY121 in Yq11.221-q11.222.