Hyderabad: Infertility hidden in Y chromosome

Hyderabad: The Centre for Cellular and Molecular Biology has found that infertility in about 30 per cent of the men it studied was caused by the genes in the Y chromosome, one of the two gender-determining chromosomes.

The common cause is said to be disease of the testes and spermatogenic defects.

Worldwide data shows that one in seven couples is infertile, and the CCMB study was conducted to get the details of the causes for infertility in India. It was found that male infertility is responsible for 8.5 per cent of the cases but India does not have data.

The large deletion of several genes of Y chromosomes was identified earlier but the scientists at CCMB looked at the micro, macro and molecular mechanisms behind the deletion events of the genes.

CCMB scientists studied three genetic domains in the ‘AZoospermia Factor’ in the Y chromosome, referred to as AZFa, AZFb and AZFc. The screening of 973 infertile men and 587 fertile men was carried out where the sperm count, motility for AZF regions and deletions using several AZF specific DNA markers and methodologies were used.

Dr Kumarasamy Thangaraj, CCMB chief scientist and senior author of the study published in Scientific Reports, explained, “The study has found that infertility in Indian men is caused  due to high rate of deletions is high when compared to other populations.

Indian populations are unique in their origin and have been practicing marrying within their tribe, community for the last 2,000 years. The actual reason for the deletion of genes is not known yet. Further studies will need to be carried out not only of Y chromosomes but also X chromosomes to understand the reason for these deletions.”

Partial deletions due to genetic mutations have been noted in populations but the complete deletions which are now showing in multiple studies needs to be addressed stated researchers.

CCMB director Dr Rakesh Mishra said, the study took the varied and widespread population of India into account to understand the deletion events. “Indian populations are genetically unique hence the novel causal deletion events of AFZ is important. The deletion can be due to many reasons but it is difficult to pinpoint one specific cause or multiple causes at this stage. The fact that there are deletions leading to infertility has been identified.”