Osteoporosis Linked to Bone Gene

Medical Author: Frederick Hecht, M.D.
Medical Editor: Barbara K. Hecht, Ph.D.

Nov. 3, 2003 -- The most significant known genetic risk factor for osteoporosis was reported today. This risk factor is on chromosome 20. It is the gene for bone morphogenic protein 2 which is called BMP2.

Osteoporosis is a common condition characterized by abnormally low BMD (bone mineral density). It sets the stage for fractures of the hip, spine, and other bones. In the US alone there are a million osteoporotic fractures a year with direct medical costs over $10 billion. X-ray tests that measure bone density can detect osteoporosis . The research fingering BMP2 was done in Iceland which has unique population resources and is proving to be a rich hunting ground for genes that predispose to common diseases.

Blood samples were collected from over 1000 Icelanders with low bone density or osteoporotic fractures. The genealogy database for all of Iceland was then used to group the patients into 207 families.

DNA typing was done next to identify a chromosome region shared by patients in the osteoporosis families. This study yielded odds of over 10,000 to 1 that osteoporosis is linked to a region on chromosome 20. The region is 20p12.3.

By sequencing this chromosome region in a total of 300 patients and controls, the researchers identified three sets of variations within the BMP2 gene that approximately triple the risk of developing osteoporosis.

These findings were replicated in Denmark where the at-risk forms of BMP2 showed a very similar correlation to osteoporosis as was found in Iceland. This confirms BMP2 as a major risk factor in osteoporosis A diagnostic test that can identify people at elevated risk for osteoporosis is being developed by deCODE, the company in Iceland that did the research, in partnership with Roche Diagnostics.

It is hoped that the test may enable those at high risk to adopt lifestyle changes and to take medications that can minimize the chances of an inherited predisposition to osteoporosis turning into a disease.

Source: U. Styrkarsdottir and colleagues. Linkage of Osteoporosis to Chromosome 20p12 and Association to BMP2. Published Nov. 3, 2003 in the online edition of Public Library of Science Biology.

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Last Editorial Review: 11/3/2003