A recent study carried out by the Centre for Cellular and Molecular Biology (CCMB) in Hyderabad has found that large deletions of the ‘Y’ chromosomes, responsible for production of sperms, could be causing infertility in Indian men. K Thangaraj, chief scientist and senior author of the study, also told TNM that prevalence of endogamy, or the custom of marrying within the tribe, caste or clan, in India could also be playing a major role in infertility among Indian men.
Scientists screened 973 infertile men and 587 fertile men, and concluded that many factors are responsible for male infertility including “chronic health problems and lifestyle choices”, but it’s genetics that play a major role. “Deletions of such genes are the most common causes of severe diseases of testes and spermatogenic defects leading to male infertility. We have earlier identified that the large deletion of Y chromosome, which consists of several genes, is responsible for male infertility in 8.5% of the cases,” a media release said.
K Thangraj added that in India, due to the popular practice of endogamy, the gene pool is reducing. “While male infertility is a problem prevalent across the world due to the deletion of Y chromosomes, its frequency is higher in India due to endogamy,” he said.
Thangaraj’s group has been studying genetic causes of male infertility for the last two decades. The earlier study carried out by the group found out large number of deletions of Y chromosomes as the reason behind male infertility but in this latest study they could study micro to macro deletion of the Y chromosomes. The scientists detected a total of 29.4% of infertile men were carrying deletions in the present study.
The study highlights that genetic isolation and endogamy, which is widespread in Indian populations, can play major roles in introducing novel causal variations. “We observed a few unique combinations of deletion events exclusively in Indian infertile men,” said Dr Deepa Selvi Rani, another lead author of this study. Dr. Rakesh Mishra, Director, CCMB added that as Indian population is genetically unique due to several factors, the higher frequency of deletions is not surprising.
Dr Thangaraj added that these findings could save investment into Assisted Reproductive Technology. “These findings have potential applications in infertility clinics. The sperm carrying Y chromosome deletion often leads to failure in assisted reproduction; so, it can be worthwhile to check for the deletion to screen infertile men prior to adopting any assisted reproduction methods.”