Gene clue to baldness

German scientists have identified a gene involved in premature baldness that is passed on from mothers to their sons. The research, published in the American Journal of Human Genetics, showed that men who inherit a particular version of the androgen receptor gene are much more likely to go bald before the age of 60. The team, based at Bonn University, say their findings could eventually lead to new treatments for baldness.

The scientists studied male pattern baldness, the most common type of hair loss in men. It usually follows a typical pattern of receding hairline and hair thinning on the crown, and is caused by hormonal and genetic factors. The researchers studied the gene for the androgen receptor, which is located on the X chromosome. Androgens are male hormones - the most well-known of which is testosterone - that are involved in the development of male characteristics. They found that one version of the androgen receptor gene was present in 70-80 per cent of men with hair loss, compared to only 40-50 per cent of unaffected men. 'There is no doubt about they involvement of this gene in male baldness', said team leader Markus Nothen.

Team member Axel Hillmer thinks that the variant androgen receptor gene probably leads to higher levels of androgens in the scalp, which in turn trigger hair loss. The location of the gene explains why many bald men have a similarly affected maternal grandfather. Men inherit their X-chromosome from their mothers, who in turn inherit one X-chromosome from each of their parents. If her father has an X-chromosome carrying a gene predisposing to baldness, then a woman has a 50 per cent chance of passing on this gene to each of her sons. However, the scientists stress that baldness involves many different genes, some of which can be passed directly from fathers to their sons. The researchers are now looking for more volunteers to take part in their studies, particularly men under 40 with severe hair loss who have an affected brother.