cytogenetic and molecular genetic analysis of dicentric y chromosome and its relation to male azoospermia

background: cytogenetic analysis, y-chromosome microdeletion screening, fish techniques and other genetic methods have helped in finding the causes of infertility in azoospermic or severe oligoazoospermic cases in the last decade. objective: in the present study, we characterized an abnormal y-chromosome, detected as a mosaic in an azoospermic male ascertained for infertility. materials and methods: chromosome analysis, using g, q and c banding techniques and fish analyses with several different dna probes specific for y and x chromosome sequences [xy centromeric α-satellite, y non-α-satellite iii, lsi-probes of the y chromosome, wcp of chromosome y, sry gene, subtelomeric xp and yp, which cover the shox (short stature-homeobox containing) gene, and subtelomeric xq and yq probes] were performed. a total of 20 sequence tagged sites were analyzed using primer sets specific for the y-chromosome microdeletion loci. the primers were chosen to cover azfa, azfb, and azfc regions as well as the sry gene. results: chromosome analysis revealed a gonosomal mosaicism of monosomy x (51%) and a pseudodicentric y (49%) chromosome: mos 45, x/46,x psu dic (y) (qter→p11.32 :: p11.2→qter). molecular genetic studies did not show deletions in the azfabc regions, but a deletion was found in the short arms of the dicentric y chromosome. one of the sry genes was also missing. conclusion: the azoospermia in this patient could be explained by either the presence of an abnormal y-chromosome that cannot form a sex vesicle (which appears to be necessary for the completion of meiosis process and the formation of sperm), or the presence of the 45, x cell line.