Archive for the ‘Gene’ Category
Male infertility has genetic, ethnic factors
Ethnic factors play a key role in determining infertility in men, a study of 560 infertile men by scientists has revealed. Some causative factors which cause infertility elsewhere do not affect Indian men, the study found. The study was conducted by Dr K. Thangaraj of the Centre for Cellular and Molecular Biology, Hyderabad, and B.N. Chakra-varthi of the Institute of Reproductive Medicine, Kolkata.
About 15 per cent of couples are infertile due to various causes. Of this, male and female factors contribute 50 per cent each. It has been estimated that genetic/ethnic factors play a role in about 10 per cent of male infertility. The ’male’ Y chromosome consists of three azoospermia factor regions (AZFa, AZFb and AZFc). A large number of genes in these regions exist in multiple copies. In addition, autosomes and X chromosomes also have genes responsible for male fertility.
The initial analysis of 560 infertile men revealed that the deletions on Y chromosome were responsible for about 12 per cent of them. To find out the molecular cause for the remaining 88 per cent of the men, the team analysed samples with other potential genes. Four copies of ‘DAZ gene’ are located in AZFc region. Deletion of one or more copies of DAZ gene was found in 16 per cent of the infertile men.
But DAZ copy deletion was found to be significant only in 5.5 per cent of the infertile men. Deletion of another gene, CDY, was found in 5.8 per cent. Analysis of the autosomal homologue of the DAZ, which was found to be associated with make infertility in some populations, is not found to be associated with male infertility in Indians. The scientists suggest that the genetic and ethnic factors play a major role in male infertility.
Male infertility: No Evidence of Involvement of Androgen Receptor Gene among Indian Men
ABSTRACT
Spermatogenesis is collaborately controlled by testosterone (T) and follicle stimulating hormone (FSH). Testosterone and its immediate metabolite, dihydrotestosterone (DHT) affect their roles through androgen receptor (AR). Mutations in AR gene have been shown to cause partial to complete androgen insensitivity or infertility in otherwise normal males. Dependence of germ cells upon Sertoli and Leydig cells for their differentiation into sperms, and deletion studies of AR gene in animal models indicate a direct or indirect role of AR gene in spermatogenesis. Although few studies worldwide have reported AR mutations in male infertility, no similar study has been conducted on Indian populations. Therefore, we undertook this study to look at the contribution of AR mutations in male infertility among Indian men. We have sequenced complete coding region of AR gene in a total of 399 infertile samples, comprising 277 azoospermic, 100 oligozoospermic and 22 oligoteratozoospermic samples. A total of 100 healthy males with proven fertility and same ethnicity served as controls. Sequence analysis revealed no mutation in any of these samples. Our study suggests that the mutations in AR gene are less likely to cause azoospermia and oligozoospermia, however, it was difficult to rule out in oligoteratozoospermia as the sample size was small.
