Genetic isolation, endogamy cause of infertility in Indian population

Hyderabad: Genetic isolation and endogamy, which is widespread among the Indian population, could be a major cause of infertility in the country’s men, a study by the city-based Centre for Cellular and Molecular Biology (CCMB) said.

According to CCMB, approximately one out of every seven couples is infertile worldwide, of which the male factors account for about 50 per cent of the cases.

Several factors are known to cause male infertility including complete absence of sperm, low sperm production and motility, blockages that prevent sperm delivery due to illnesses and injuries, chronic health problems, lifestyle choices while genetic factors play a major role in most of these cases. A team of scientists at CCMB led by Chief Scientist K Thangaraj has been studying the genetic causes of male infertility for the last two decades, a release from the Centre said.

“Y chromosome consists of several genes that are responsible for production of sperms, i.e. spermatogenesis. 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 per cent of the cases,” Thangaraj noted.

“In the present study, we have studied the micro to macro deletions on the Y chromosome and the molecular mechanisms behind the deletion events,” said Thangaraj, who is the senior author of the finding, which was published online on April 18 in ‘Scientific Reports.’

According to CCMB scientists, the study, conducted recently, highlights that genetic isolation and endogamy, which is widespread in Indian populations, can play a major role in introducing novel causal variations.

“Hence, the authors undertook the study and found various deletion events of AFZ regions on the Y chromosome in the diverse Indian population and their association with male infertility,” the release said.

AZoospermia Factor (AZF) regions consist of three genetic domains in the long arm of the human Y chromosome referred to as AZFa, AZFb and AZFc, and they are home to genes required for spermatogenesis.

Thangarajfurther said these findings have potential applications in the infertility clinic.

“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 adapting any assisted reproductive methods,” he added.