Mutant sperm


For many couples struggling to have children, the source of their infertility issues remains a mystery. Researchers now suggest that some infertility could be explained by a mutation that keeps sperm from reaching eggs.

Male infertility mystery

Infertility affects 10-15% of the US population. The source of the infertility is fairly split between men and women. The interesting thing about male infertility is that many times there is no visible flaw with the sperm. The quality and quantity appears to be intact. “In 70% of men you can’t predict their fertility on the basis of sperm count and routine assessment of quality,” said researcher Gary Cherr at the University of California at Davis.

Cloaking device for sperm

New clues led Cherr and his team to look more closely at a gene called DEFB124 which encodes beta-defensin 126, a germ killing class of proteins. While the sperm is still in the epididymis, it is coated with this gene. It helps the sperm swim through the mucus of the cervix. The gene helps the sperm get through safely and undetected by a woman’s body defenses.

Some men lack this cloaking device. Their sperm look and act completely normal, but they are vulnerable. When an analysis was done on 500 newly married couples, it was discovered that men who had a mutation of this gene were 40% less likely to become pregnant than other couples.

Could explain falling fertility globally

Human fertility is falling worldwide. It may be that an increase in this gene abnormality has something to do with it. Future research could lead to better testing for this defect, both in the lab and at home. Treatments of synthetic defensing are also possible. “You can concentrate it in a vaginally applied cream or gel, and sperm would pick up this defensing coat as they advanced into the cervix,” said Cherr.

Source: Science Translational Medicine


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