X Chromosome Gene Essential For Sperm Cell Development, Male Fertility, Says New Study

The study found that the loss of the X chromosome gene (TEX13B) reduces the respiratory ability of the cells. They also found that TEX13B controls energy metabolism in the sperm-producing cells. The TEX13B is present on the X chromosome, which all males receive only from their mothers. The Release highlights how genetic trait transmissions can be more complex, and more nuanced than it is superficially thought.

Hyderabad:Researchers from the city-based CSIR-Centre for Cellular and Molecular Biology and other institutions have identified, for the first time, that the X chromosome gene (TEX13B) is essential for sperm cell development and male fertility.

The CSIR-Centre for Cellular and Molecular Biology (CCMB) said on Thursday that approximately, one in every seven couples is infertile worldwide. The male factors account for 50 per cent of total infertility due to abnormal semen parameters, such as low sperm count, abnormal motility of sperm, and abnormal sperm shape and size. One of the important factors behind these causes is the genetic factor.

In a new multi-institutional study, scientists at the CSIR-Centre for Cellular and Molecular Biology, "identified, for the first time, that the gene TEX13B is essential for sperm cell development and male fertility", a CCMB release said.

The study has recently been published in the journal Human Reproduction.

"Using next-generation sequencing, we compared all the gene coding regions (exons) between infertile and fertile males. We found two causative mutations in the TEX13B gene, of which one was exclusively found in infertile men and the other one is found much more frequently in infertile men compared to fertile control men," said Umesh Kumar, the first author who was a PhD student of CCMB.

The researchers have developed a cell culture model of mouse sperm-producing cells by knocking out the Tex13b gene using 'CRISPR-Cas9' technology.

They found that the loss of the Tex13b gene reduces the respiratory ability of the cells. They also found that Tex13b controls energy metabolism in the sperm-producing cells. Together, they argue that this affects the formation of new sperm cells, the release said.

"The findings of this study would be useful for screening infertile males with spermatogenic failure and counselling them before the implementation of assisted reproduction technique(s)," said Vinay Kumar Nandicoori, Director, CCMB.

The study reminds us how genetic trait transmissions can be more complex, and more nuanced than it is superficially thought, the release said.

"The TEX13B is present on the X chromosome, which all males receive only from their mothers, and not from their fathers. It means that the mother who carries the faulty TEX13B is fertile (as she carries two X chromosomes). But, when she transmits the X chromosome with the faulty TEX13B, her son becomes infertile. This is not what we generally expect to be an underlying cause of male infertility," said K Thangaraj, a leading scientist at the CCMB.