Bald times two

Two separate studies in Nature Genetics have identified new genetic risk factors for male-pattern baldness.

One, a two-stage genome-wide association study of a total of 4961 men and women co-ordinated by King’s College London, found two genetic variants that, when present together, increase the risk seven-fold.

Male-pattern baldness, or androgenic alopecia, has very high heritability, with some estimating it at over 80 per cent, co-author Professor Tim Spector said.

Previous studies have shown that variants in the androgen receptor (AR) gene on the X chromosome were associated with male-pattern baldness. Spector’s study found that these variants, when found added to variants on chromosome 20, were found in one in seven Caucasian men and increased their risk seven-fold.

The findings were backed by a separate study by the University of Bonn’s Axel Hillmer and colleagues, who studied a total of 643 men and women and found five single nucleotide polymorphisms (SNPs) on chromosome 20p11.

Hillmer’s study was confined to people of German descent so was compared with an Australian sample co-ordinated by Professor Nick Martin of the Queensland Institute of Medical Research in Brisbane, which showed significant association.

Spector’s cohort included people of Swiss, Dutch, British and Icelandic descent.

“Male-pattern baldness susceptibility locus at 20p11” by J Brent Richards et al [doi:10.1038/ng/255] and “Susceptibility variants for male-pattern baldness on chromosome 20p11” by Axel M Hillmer et al [doi:10.1038/ng.228] were published in advance online yesterday in Nature Genetics.