Infertility in Indian men linked to marrying within community
doi:10.1038/nindia.2019.48 Published online 24 April 2019
One of the reasons for infertility in Indian men, as compared to other populations, could be endogamy, or the practice of marrying within a specific social group, according to a new study1 led by the Centre for Cellular and Molecular Biology (CCMB), Hyderabad. Endogamy might be triggering a very high frequency of deletion of genes in a region responsible for the production of sperms, the study says.
Azoospermia Factor (AZF) is a region in the long arm of human Y chromosome that hosts the genes responsible for production of sperms. Deletion of genes in this region is associated with inability to produce sperms. Although several studies have reported that the deletions in AZF region is associated with male infertility, there had been no comprehensive study to correlate the two in Indian men till now.
The researchers screened for AZF region deletions in 973 infertile Indian men with normal sperm count and found that 29.4 per cent of them had gene deletions – much higher than those reported in similar studies done in populations elsewhere. They also observed "a few unique combinations of deletion events exclusively in Indian infertile men.”
"This study illustrates how ethnicity, endogamy and long-time geographical isolation of Indian populations might have played a major role in the high frequencies of deletion events (leading to infertility)," the authors report.
The findings have an important message for infertility clinics, they note. For successful results, these clinics may have to screen men for deletion of AZF regions in their Y chromosome prior to using their semen in any assisted reproductive methods.
The authors conclude that further analyses of genes – not only of the Y chromosome but also of the X chromosome and the autosomes (not sex chromosomes) – are required to understand the genetic causes of male infertility in Indian men.
1. Rani, D. S. et al. High frequencies of non allelic homologous recombination (NAHR) events at the AZF loci and male infertility risk in Indian men. Sci. Rep. 9, 6276 (2019) doi: 10.1038/s41598-019-42690-0