Men with a minor gene mutation produce more of the hormone testosterone and may have stronger, larger bones, according to Joseph Zmuda, research associate at the University of Pittsburgh Graduate School of Public Health, in a presentation delivered Sunday, Oct. 3, at the national meeting of the American Society for Bone and Mineral Research.
"We know that men with a family history of the bone-weakening disease osteoporosis are more likely to develop this disease, so it appears there are genes involved," said Mr. Zmuda. "Finding these genes may eventually lead to better ways of diagnosing and treating osteoporosis."
Mr. Zmuda's research shows that men who carry a common mutation in the cytochrome P450c17 (CYP17) gene produce more testosterone and have larger, stronger bones. CYP17 is responsible for making testosterone, a hormone that is important in developing strong bones.
The CYP17 gene naturally comes in several forms, or alleles, with an individual inheriting one allele from each parent. Two common alleles are known as 'C' and 'T.' The combination of two inherited alleles is referred to as a 'genotype.'
The University of Pittsburgh study measured hormone levels, stature and the mass and size of the hip bone in 333 Caucasian men aged 51-84 years. While age and body weight did not differ by CYP17 genotype, researchers found that blood testosterone levels were 20 percent higher in men with two 'C' alleles (C/C), compared with men who had two 'T' alleles (T/T). Men with the C/C genotype were taller and had larger bones.
"Osteoporosis is a complex disease, and it is unlikely that there is a single gene that causes this disorder in most people," said Mr. Zmuda. "But this study is a step toward our goal of understanding the genetics of osteoporosis. We intend to conduct further research to see if having the CYP17 mutation is connected with the risk of osteoporosis-related fractures in men."