submicroscopic deletions of the y chromosome are not limited to azoospermic men, but are also detected in infertile men with idiopathic oligozoospermia

it is now agreed that 10-25% of infertile men with azoospermia have submicroscopic deletions of the y chromosome long ann (yq), consistent with the proposed location of the azoospermia locus (azf) in yq 11.23. however, it is not known whether yq microdeletions are unique to men with azoospermia or whether they are also observed in infertile men with less severe defects of spermatogenesis (oligozoospermia). the objective of this study was to determine the prevalence of yq deletions in infertile men with idiopathic oligozoospermia dn a was extracted from blood lymphocytes of 45 oligozoospermic men (sperm densities <20 million/ml) in whom known causes of infertility had been excluded. all subjects were typed for the 27 y -specific stss that have been mapped to deletion interval 6. an sts was considered negative if no pcr product was observed in 3 reactions, in which a fertile male gave a specific pcr product and anorma1 female dna did not. whenever sufficient dna was available, deletions detected by pcr were verifed by southern hybridization. of the 45 oligozoospermic men, 4 (9010) had deletions of one or more stss. these deletions were verified by southern hybridization. all. 4 deletions were located in distal interval 6 (6c and 6d) and included the daz (deleted in azoospermia) gene, a y-specific gene that has been proposed as a candidate for male infertility. all four patients had sperm densities of less than 1 million/ml and three out of these 4 patients had mean testis volume of less than 15 ml. two of the infertile men with y deletions had a testicular biopsy testicular histology in both of these patients was consistent with germ cell arrest, spermatocyte stage. yq microdeletions are not unique to infertile men with azoospermia but are abserved also in infertile men with oligozoospermia taken together with previously reported studies on azoospermic men, these results indicate that yq deletions are predominantly obselved in, but are not limited to, infertile men with relatively severe defects of spermatogenesis.