Gene offers clues about male infertility

Scientists have identified a gene in mice that is essential for the production of healthy sperm. The mouse gene, called Hrb, is nearly identical in human males, and studying mice that lack Hrb may yield clues about male infertility. The study was carried out at the Mayo Clinic in Rochester, Minnesota. They found that the lack of a normal Hrb gene product affects fertility in mice. The Hrb gene is responsible for making a structural component called the acrosome, which is located on the tip of the sperm. It is a compartment that caps the sperm and is filled with enzymes required for fertilization. The acrosome develops by fusion of many smaller compartments. In their study, the researchers found that mice lacking the Hrb gene were unable to produce sperm that could fertilize an egg. Careful examination of sperm from these mice revealed defects in the acrosome. The study shows that defects in the mouse Hrb gene causes infertility in the absence of other abnormalities. It is reasonable to assume that Hrb mutations in men could similarly lead to infertility. While the current findings offer no immediate benefits for the treatment of infertility in men, the mouse model that has been generated may be useful for further testing and treatment of infertility.