| Background:It has been estimated that up to 10% of couples worldwide suffer from infertility and in approximately half of these cases the cause is defective spermatogenesis. Azoospermia and oligozoospermia of unknown origin, in which obstruction of the vas deferens, other obvious urological reasons and klinefelter syndrome have been ruled out, may be due to the abnormality of genes crucial to spermatogenesis. In regard to spermatogenesis gene, particular attention has been given to the Yqll region. The Y chromosome comprises 2% of the genome and consists of a short (Yp) and long arm (Yq). 1976,Tiepolo and Zuffardi frist reported, from microscopic analysis of the Y chromosome in infertile men, that the human Y chromosome played crucial role in spermatogenesis. Cytogenetic and molecular studies of azoospermic and oligozoospermic males have suggested the presence of azoospermia factors (AZF) in the human Y chromosome. Through the use of molecular markers that have been mapped at density on the Y chromosome, numerous deletion-mapping studies have defined at least three distinct non-overlapping intervals each associated with variable degrees of spermatogenic impairment. Three regions located on the long ami of the Y chromosome were named azoospermia factor (AZF)-a, -b, and -c.Deletion in three Y chromosomal regions-AZFa, AZFb, and AZFc-has been reported to disrupt spermatogenesis and cause infertility. Several candidate genes responsible for spermatogenesis have been identified in these regions and some of them are thought to be functional in human spermatogenesis. In 1993,Ma reported two cDNAs of a Y-specific gene family named the RNA binding motif (RBM) from a region on the long arm of the Y chromosome that was deleted in some infertiles patients. In 1995, DAZ (Deleted in azoospermia) was identified from analysis of AZFc interval in the long arm of the Y chromosome in azoospermic men. Although RBM and DAZ are not only gene present in this region, RBM and DAZ genes were isolated as candidate genes in controlling spermatogenesis from the AZFb and AZFc regions, respectively. Both of them encode proteins that bind RNA and might be involved in its regulation and metabolism.The finding of a genetic aetiology in patients with idiopathic azoospermia and oligozoospermia suggests that in such patients a Yq microdeletion screening should be performed, both for proper diagnosis and to avoid unnecessary treatments that will probably not improve the sperm count. With the advances in artificial reproductive technology, microdeletions of the Y chromosome will be transmitted to male offspring, and these sons will be at risk of having the same infertility problem. Actually, Kent-Frist demonstrated that microdeletions were transmitted to male offspring via intracytoplasmic sperm injection (1CSI), This possibility should be conveyed to infertile couples with an explanation of the analysis of microdeletion of the Y chromosome.Object:The aim of this study was to assess the frequency of such deletions in men with idiopathic azoospermia and severe oligozoospermia and to discuss the clinical significance of the AZF region dection.Material and Method:Group patients: All patients consulted our infertility clinic. Clinical subjects were patients with male infertility of unknown origin aged between 28~42 years. Selected fifty patients were referred for clinical examination to exclude varicocele ,epididimal lesions, cryptorchidism , obstructive azoospermia or other obvious urological reasons; Semen samples of azoospermia and severe oligozoospermia (2~5 x 106ml) were obtained on three different occasions, separated by a 3-week interval, following a 3-day period of sexual abstinence ,and complete semen analyses were performed according to the World Health Organization guidelines; All patients had a normal 46XY karyotype; they also had normal plasma concentrations of sex hormone; in addition, paraffin-embedded testicular tissues of thirty-eight azoospermia patients were evaluated histologically. Group health controls: Fi...
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