Defunct sperm pinned on mutated gene

More than 20 million men worldwide are infertile. Several gene mutations are known to impair the motility of sperm — a critical function in the race to fertilize the egg. A team of researchers from France and Tunisia, led by Pierre F. Ray from Université Joseph Fourier, France, has identified four mutations in the gene dynein heavy chain 1 (DNAH1), which codes a motor protein in the sperm's tail, that leads to infertility

The scientists performed a whole-genome scan on 20 infertile men with impaired sperm motility living in Tunisia, Algeria and Libya, publishing their results in the American Journal of Human Genetics.

The DNAH1 gene encodes a protein that forms a complex network of dynein proteins found in sperm flagella. By using diagnostic markers for dyneins, the researchers found that the mutations in DNAH1 led to a highly disorganized axoneme, the core structure of flagella. This resulted in abnormal flagella with 0–2% sperm motility in most of the studied patients.

"We hope to develop new therapies for infertile couples by introducing a functional protein in the testes of affected men," says Ray.

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