| Infertility occurs in 15% of all reproductive age couples in the world. Approximately half of the cases are due to male factors. Studies on genetic epidemiology of male infertility demonstrated that autosomal recessive gene mutation and multiple gene hereditary basis are the genetic load of male infertility, which is the reason of high incidence for male infertility. It is presumed that more than 60% male infertility with undefined reasons is caused by autosomal recessive gene mutation. DAZL on chromosome 3 may be the pathogenetic gene of autosomal recessive male infertility. DAZL locates in autosomal 3p24, encodes protein containing 295 aa with a molecular weight of 33170D. DAZL gene expresses in testis and ovary in the embryonic stage, but for adult abundantly in testis, weakly in ovary. It can not be found in other tissues. Homologies of DAZL in many species are important for differentiation of germ-cell. DAZL might also be mainly involved in the major morphological changes during spermiogenesis when the elongated spermatids and mature motile spermatozoa are formed. In 1997 Ruggiu et al found heterozygous DAZL-deficient mice, displayed a higher percentage of malformed spermatozoa, compared to normal mice. Schrans-Stassen et al proved that removal of the autosomal DAZL gene in knockout mice resulted in infertility in the year of 2001. Lin YM et al found that concentrations of DAZL transcripts were lower in men with spermatogenic failure. It had been reported by Teng YN that the SNP386 polymorphism of the DAZL gene was associated with spermatogenic failure for Taiwanese population in 2002. Tschanter P et al failed to demonstrate any associations of SNP 260 mutation with spermatogenic impairment; but the frequency of AG for SNP 260 was significantly elevated (39.3%) in patients harbouring an AZFc deletion compared with the control group (24.2%). Moreover, the single homozygous GG mutation was found in the AZFc deletion group. Because of the limited numbers of patients...
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