OBJECTIVEThe past few years have seen great progress in the studies of the relationship between AZF microdeletions and male infertility. However, some molecular and clinical concerns are not supported by definitive data. The aim of this study was to investigate the prevalence and types of AZF microdeletions in infertile Chinese men, and the indications for genotype-phenotype correlation.

METHODSWe retrospectively analyzed Y chromosome AZF microdeletions among 502 patients with nonobstructive azoospermia and 306 with severe oligozoospermia received in our hospital during the past five years.

RESULTSMicrodeletions were detected in 7.80% of the patients (63/808), 9.16% in the men with nonobstructive azoospermia (46/502) and 5.56% in those with severe oligozoospermia (17/306). Complete AZFa and AZFb (P5/Proximal P1) deletions were associated with azoospermia, whereas AZFc deletion with variable spermatogenic phenotypes. A mild decline in sperm concentration was found in one male with partial AZFb deletion. The most frequent deletion was the AZFc b2/b4 subtype (60.32%, 38/63), and 39.47% of the cases (15/38) had sperm in the ejaculate. Of the 63 deletions, only one case of the AZFc b2/b4 type had a sperm concentration of over 2 million sperm/ml.

CONCLUSIONAZF microdeletions play a significant role in the diagnosis and evaluation of spermatogenic defects. Larger-scale clinical researches on Y chromosome microdeletions may give us a deeper insight into their mechanism and the genotype-phenotype relationship.