Genetic link to baldness discovered
A new genetic link to baldness has been discovered that may explain why many men inherit hair loss from their fathers.
1:54PM BST 12 Oct 2008
Source: telegraph.co.uk
The nature of the variants is still a mystery but one of them may influence male hormone activity through a gene.
Previously the only genetic association with male baldness known was a variant on the female X chromosome.
This risk factor is passed down the mother's side of the family.
It may account for bald men taking after their maternal grandfathers, but baldness is also often passed from father to son.
The new discovery could help researchers looking for ways to treat inherited male hair loss.
One of the scientists, Dr Tim Spector, of King's College London, said: "Early prediction before hair loss starts may lead to some interesting therapies that are more effective than treating late stage hair loss."
Colleague Dr Brent Richards, from McGill University in Montreal, Canada, said: "We've only identified a causes. Treating male pattern baldness will require more research. But, of course, the first step in finding a way to treat most conditions is to first identify the cause."
Two separate international teams led by Dr Spector and Dr Axel Hillmer, from the University of Bonn in Germany, reported similar findings in the journal Nature Genetics.
Dr Spector's group, which included Dr Richards and colleagues from Iceland, Switzerland, the Netherlands and pharmaceutical giants GlaxoSmithKline, carried out a genetic study of 1,125 Caucasian men.
Inherited baldness among the men was found to be closely associated with genetic variations at two locations on chromosome 20.
The chromosome, one of the bundles of DNA in every cell that contain the genes, can be inherited from either the mother or father.
Dr Richards said: "It's long been recognised that there must be several genes causing male pattern baldness. Until now, no-one could identify those other genes. If you have both the risk variants we discovered on chromosome 20 and the unrelated known variant on the X chromosome, your risk of becoming bald increases sevenfold."
The German-led scientists focused on around 300 men with serious hair loss, scouring 500,000 variable sites in their genetic codes. They found a clear association between baldness and the same two variants on chromosome 20.
One of the variant regions harbours a gene for a biologically active receptor protein that is sensitive to male hormones.
Dr Felix Brockschmidt, from the University of Bonn, said: "We are now trying to discover the role played by this genomic region in hair growth. Only then will we know whether we are on the right track for new forms of therapy for male hair loss."
Male pattern baldness, the most common form, causes hair to be lost in a well-defined pattern beginning above both temples. It results in a distinctive M-shaped hairline.
Estimates suggest that more than 80% of cases of male pattern baldness are hereditary.
An estimated 14% of men are thought to carry the two chromosome 20 variants.
