OBJECTIVETo evaluate the frequency of microdeletions in the long arm of Y chromosome of idiopathic infertile males with azoospermia and oligospermia in Shaanxi province in China and to investigate the relevance of sperm count to Y microdeletion frequencies.

METHODSAccording to the sequence of sequence-tagged sits (STS) AZFa, AZFb, AZFc and SRY, 4 of the azoospermic factor regions on Y chromosome long-term supplied by GenBank, 5 sets of primers were synthesized. The Y microdeletions in AZF regions were screened by polymerase chain reaction (PCR) in 64 idiopathic cases of azoospermia and oligospermia and 20 men of known fertility.

RESULTSNo microdeletion was detected in the 20 normospermic subjects. Deletion of the AZFc/DAZ was detected in 11 individuals and one patient had both AZFb and AZFc deletion; no deletion of AZFa and SRY region was found. The frequency of Y microdeletions in the subgroups with different sperm count showed the highest value among azoospermic men (3 cases, 21.4%). The percentage progressively decreased with the deletion frequency (20.0%, 17.9% and 8.3%) in the subgroups with sperm counts of < 1 x 10(6)/ml, < (1-5) x 10(6)/ml and < (1 to approximately 10) x 10(6)/ml, respectively.

CONCLUSIONY chromosome microdeletions are specifically associated with severe spermatogenic failure. The rate of deletion involving AZF region of the Y-chromosome is higher in infertile men with azoospermia and oligospermia. PCR amplification of AZF locus is useful for the diagnosis of microdeletions in the Y-chromosome.