Thursday, February 28, 2008

Going Bald: Thanks Mom!

Men who start to go bald even before a mid-life crisis may have their mothers to blame, according to a new study. Researchers have found that the main construction manual for a full head of hair is located on the X chromosome, which sons always inherit from their mothers.

This genetic storage space contains the so-called androgen receptor gene, a long time balding suspect. Looking at men who were losing their hair at a relatively young age, a team led by Markus Nothen, PhD, of the Life & Brain Center at Bonn University, Germany systematically examined all of the genetic patterns within the X chromosome to see why certain hairlines recede faster than others.

It's not a pretty picture. The study, published in the American Journal of Human Genetics, claims that a single alteration in the androgen-receptor gene is the major reason why some men end up going bald before their fathers.

Nearly half of bald men would not be bald if they did not have this genetic variation, said Nothen. The hair loss in these younger men, he added, was much more severe than in the men who still had a reason to use a comb in their 60s.

There are clearly other genetic factors involved with balding, said Nothen, "which is obvious when we look at non-affected men over 60 years of age." About 40 percent had the same genetic alteration, yet managed to keep their hair, he said. Still, the findings help define why some vulnerable men may be at risk for early hair loss.

As part of the study, Nothen and colleagues looked at 95 families in which at least two brothers started going bald before they turned 40. DNA was collected from 200 young, balding men and compared to their hairier brothers, as well as some 150 unrelated guys in their 60's who still had a full head of hair.

The men with an alteration in the androgen-receptor gene had a 46 percent higher risk of going bald before the age of 40. This variation essentially acts like a repeat button, churning out more bald genetic code than normal. To the study authors, this suggests that a guy can lose his hair because he has more of these androgen receptors on his scalp. How this excess happens is not really clear. The researchers are planning further studies to find out.

Many key insights into balding have relied on animal models, but the current research "is truly relevant to human hair loss," said George Cotsarelis, PhD, an expert on the genetic causes of hair loss from the University of Pennsylvania School of Medicine. Still, he added that the small number of men who were studied makes it hard to determine if new hair growth interventions can sprout up anytime soon.

Like other studies, the German findings point to excess androgen receptors as a key target for saving hair. Designing a drug to block these receptors may keep the need for toupees at bay, but they could also interfere with male hormones that men need to be men. Ideally, a topical cream could be developed that blocks just the male hormones responsible for shiny scalps. In the meantime, men concerned about hair loss should not give up hope. "The research raises the chance that something can happen," said Cotsarelis.