Bare truth

New Delhi, Oct. 12: Scientists today announced the discovery of genes linked to male pattern baldness, a common condition that affects about 40 per cent of adult men and women.

Two research groups scattered across Europe, North America and Australia have independently identified a genetic region on chromosome 20 that increases the risk of baldness. Their findings, to appear in the journal Nature Genetics tomorrow, suggest that hair loss, long suspected to be hereditary, is driven by more than one gene.

Scientists in Germany and Australia scanned 500,000 positions on the genomes of 296 men and found a gene variant that occurs more frequently in bald men than in those without hair loss.

“We’re now trying to discover the role played by this genomic region in hair growth,” said Felix Brockschmidt, a team member from the University of Bonn, Germany.

A genetic basis of baldness may help researchers find new strategies to tackle hair loss.

Male pattern baldness starts with hair loss above both temples and eventually leads to an M-shaped hairline.

Medical experts have estimated that global revenues for baldness therapy have crossed $400 million.

The first gene implicated in hair loss about three years ago was the androgen receptor inherited from mothers, and explained why hair loss in men sometimes reflects patterns displayed by their maternal grandfathers.

The second study by researchers in Canada, Iceland, the UK and the US also identified a gene variant for baldness on chromosome 20. The gene may be inherited from the mother or the father and could explain how a son with a bald father is at a higher risk of hair loss.

The study led by Tim Spector at King’s College, London, found that a man with the gene variant on chromosome 20 as well as the androgen receptor has a seven-fold higher risk of losing hair. “The strong genetic basis of hair loss is odd — for any evolutionary advantage (of hair loss) is unclear,” said Spector.

Scientists believe that genetic variants that appear in relatively high frequency among individuals confer some advantage to them.

However, researchers suspect that the mechanisms involved in hair loss may be shared with heart disease, hypertension and insulin resistance in men, and polycystic ovarian disease and insulin resistance in women.

Hair loss occurs in women but is not easily recognisable as there are also cases of non-male pattern hair loss.

Spector’s study of 1,650 men showed that one in seven men carry both gene variants. Both studies examined only Caucasian men, so experts couldn’t say for certain if the findings would apply to non-Caucasians.

Brockschmidt and his colleagues have suggested that the frequency of the gene variant for baldness may differ from population to popu- lation and may account for variations in baldness patterns worldwide.