Investigation Of Y-chromosome Microdeletions In Male Infertility

Infertility occurs in 10 ~ 15% of all reproductive age couples. Approximately half of the cases is due to male factors. There are many factors resulted in male infertility. Majority is associated with sperm count, morphology and motility. Men with oligospermia, asthenospermia, teratozoospermia and azoospermia account for 20~25% of the cases. The rapid growth of assisted reproductive techniques and, in particular, of intracytoplasmic sperm injection (ICSI) has contributed to a breakthrough treatment for male oligoasthenospermia including azoospermia. Unfortunately, ICSI allowed a spermatozoon with chromosomal abnormalities, deletions or mutations of genes to fertilize an oocyte as bypassing natural selection, thus transmitting the genetic defects to the offspring. Due to the development of molecular biology and genetics, and the establishment of Y chromosome physical map, the study of male infertility etiology has reached in molecular level. Research in the last 30 years has resulted in the findings of more than 15 genes and gene families that locate in human Y chromosome and control spermatogenesis. They are located in three non overlapping regions of Yq11,named AZFa, AZFb and AZFc. These findings contribute not only to the further understanding of the regulation of spermatogenesis, but also to the study of causes and diagnoses about male infertility by molecular biological methods. The objective of this study is to evaluate the incidence of Y chromosome microdeletions in patients with azoospermia or severe oligozoospermia and to investigate the relationships between the microdeletions and their clinical phenotypes. We set up a screening method to detect Y chromosome microdeletions in male infertility for the purpose of laying a foundation of clinical diognosis and providing genetic information for ICSI patients. Ninety-three patients with forty-two azoospermia and fifty-one severe oligozoospermia were recruited in present study. Y chromosome microdeletions were screened by detection of four locus SY84, SY134, SY255 and SPGY1 gene spaning the AZFa, AZFb and AZFc subregions of Y chromosome. The total incidence of Y microdeletions was 16%( 15/93 )in present study. Eight men in 42 patients with azoospermia had Y microdeletions, of whom 6 were AZFc deletion and 2 were AZFb deletion. Seven men in 51 patients with oligozoospermia had Y microdeletions, all of whom were AZFc deletion. No AZFa deletion was detected in all patients. Present results imply that Y chromosome deletions are one of important causes of male infertility. AZFc deletion is associated with both azoospermia and severe oligozoospermia. AZFb deletion correlates with severe hypospermatogenesis. It is suggested that all infertile men with azoospermia or severe oligozoospermia should undergo Y chromosome microdeletion analysis before they have the treatment of ICSI.