Veterinary researchers from University of Pennsylvania, USA, have identified a gene, called TEX11, which is on the X chromosome, that causes sterility in male mice and reduces female fecundity when disrupted. This study is the first that searches genetic causes of infertility linking a particular sex chromosome to sterility.

The TEX11 is also found on the human X chromosome. Since the disruption of this gene causes azoospermia in mice, mutations in this gene in humans may be a genetic cause of infertility in men. Men have only one X chromosome, inherited from their mother and therefore only one copy of the TEX11 gene. That is why any mutation of the gene can lead to sterility: this means that genetic mutation causing a son´s infertility could be passed from his mother. The team of researchers believe that a screening of the TEX11 gene could provide a pre-birth diagnosis for infertility in men.

The study lead by these researchers reports the first meiosis-specific factor ever found on the X chromosome. Meiosis is the process of cell division that produces gametes in both sexes. During this process, exchange of genetic material between mother and father takes place, and that is why any defect in meiosis is a leading cause of infertility and birth defects.

During the initial stages of meiosis, the TEX11 gene has a significant role that, when disrupted, causes homologous chromosomes to fail to pair together during meiosis. These failures can lead to elimination of spermatocytes at later stages in the genetic recombination process and, eventually, to male infertility.

Researchers hypothesize that because TEX11 interacts with SYCP2, an integral component of the protein complex that mediates synapsis during meiosis, TEX11 promotes both synapsis and genetic recombination and may provide a physical link between these two meiotic processes.