US study: Male infertility related to protein gene

Jul 20, 2011, 19:08 GMT

Washington - A new study on the causes of infertility may give struggling couples a reason to celebrate, a team of scientists from the University of California Davis said Wednesday.

A defective gene found in males, which reduces the amount of protein surrounding their sperm, could be the key to diagnosing one-fifth of unexplained infertility cases.

In normal circumstances, the protein in question - DEFB126 - acts like a 'Klingon cloaking device' and allows sperm to swim through mucus, dodge the immune system and reach the egg, said Gary Cherr, senior author of the study published in the Science Translational Medicine journal.

Without this protein, sperm is unable to penetrate the cervical mucus wall.

Cherr believes this breakthrough could help doctors better diagnose infertility and provide couples a less expensive solution to getting pregnant.

The study, which involved men in the US, Britain and China, showed that up to 20 to 25 per cent of men carry two copies of the defective gene that lacks the protein.

The mutation was found to reduced a couple's ability to get pregnant by 60 per cent, compared to those with the normal gene, scientists said.

The discovery could help clear up some of the mystery as to why there is no real explanation of infertility for about 70 per cent of infertile men. Cherr said the normal standards - sperm count and quality - are not helpful in explaining much of male infertility.

Cherr and his team hope the discovery will help scientists develop a test that will detect the mutated gene early and help couples bypass expensive procedures that are unlikely to work with the mutation present.

Instead, couples could be immediately directed to in-vitro procedures where doctors inject sperm directly into the egg.