Researchers at McGill University, King’s College London and GlaxoSmithKline Inc. have identified two genetic variants in caucasians that together produce an astounding sevenfold increase the risk of male pattern baldness. Their results will be published Oct. 12 in the journal Nature Genetics.

About a third of all men are affected by male pattern baldness by age 45. The condition’s social and economic impact is considerable: expenditures for hair transplantation in the United States alone exceeded $115 million (U.S.) in 2007, while global revenues for medical therapy for male-pattern baldness recently surpassed $405 million. Male pattern baldness is the most common form of baldness, where hair is lost in a well-defined pattern beginning above both temples, and results in a distinctive M-shaped hairline. Estimates suggest more than 80 per cent of cases are hereditary.

This study was conducted by Dr. Vincent Mooser of GlaxoSmithKline, Dr. Brent Richards of McGill University’s Faculty of Medicine and the affiliated Jewish General Hospital (and formerly of King’s College), and Dr. Tim Spector of King’s College. Along with colleagues in Iceland, Switzerland and the Netherlands, the researchers conducted a genome-wide association study of 1,125 caucasian men who had been assessed for male pattern baldness. They found two previously unknown genetic variants on chromosome 20 that substantially increased the risk of male pattern baldness. They then confirmed these findings in an additional 1,650 caucasian men.