The work done in Germany paralleled a study led by researchers at Kings College London, with the results of that study differing slightly. It included 1,125 men assessed for male pattern baldness. Two regions on chromosome 20 were found to be associated with the condition. And a further study of another 1,650 men found a sevenfold increase in the incidence of baldness in the one in seven men carrying variants in both the X chromosome and chromosome 20 regions.
The new results "are certainly putting us closer to a genetic test for developing alopecia," said Dr. George Cotsarelis, director of the Hair and Scalp Clinic at the Hospital of the University of Pennsylvania.
But, he added, a negative reading on such a test would be more informative than a positive result showing the presence of the baldness-related genes.
"If you don't have the genes, there is a negative predictive value of 96 percent," he said. "If you do have the genes, there is a positive predictive value of about 14 percent."
The currently marketed genetic test got a low grade from Cotsarelis. "It can predict baldness 60 percent of the time, and 50 percent of men will become bald," he said.
Learn more about what's known about male pattern baldness at the U.S. National Library of Medicine.
SOURCES: Felix F. Brockschmidt, Ph.D., postdoctoral fellow, University of Bonn, Germany; George Cotsarelis, M.D., director, Hair and Scalp Clinic, Hospital of the University of Pennsylvania, Philadelphia; Oct. 12, 2008, Nature Genetics, online
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