Possible DNA repair link to male infertility

A team of US researchers, based at the University of California, San Francisco, has found evidence of faulty DNA repair in the testes of some infertile men. Their findings, published in the June issue of Human Reproduction, could throw light on previously unexplained cases of male infertility, but may also have implications for some children conceived using ICSI (intracytoplasmic sperm injection).

DNA copying errors can occur every time a cell divides, but in a normal, healthy cell these mistakes are corrected by an efficient DNA repair system. The researchers studied five men with normally functioning testes, and five men whose testes made little or no sperm. These men had 100-fold higher error rate in their DNA than the men with normally functioning testes, said Dr Reijo Pera, who led the team.

Although only a small study, author Dr Paul Turek says it raises several questions. Faulty DNA repair is associated with several forms of cancer, an association that Dr Turek describes as 'worrisome'. One concern is the health of pregnancies and children conceived using ICSI - the injection of a single sperm directly into an egg.

If children with DNA repair defects survive to term, they may have an increased risk of developing cancer later in life, say the authors. Boys may also inherit their father's infertility. But Dr Pera said inherited DNA repair problems may instead result in miscarriages, suggesting babies who make it to term would not have this problem. 'We don't know which scenario will be true', said Turek, adding that researchers should follow up on the health and development of ICSI children of men with infertility due to testes failure, to help sort out these issues.

A study of 1000 ICSI children, published in the April issue of Human Reproduction, found no evidence of any increased health risks linked to the technique.