Scientists at the Icelandic firm deCODE have identified several genetic variations that could play a key role in osteoporosis. People who inherit an altered version of the BMP2 gene are more likely to develop the bone-weakening disease, the team report in the journal PLoS Biology. They stress that several other genes are also likely to be involved, and that factors such as exercise and diet are also crucial. But looking for key genes involved in osteoporosis could help develop new treatments, and also identify people at high risk of the illness, the scientists say.
Osteoporosis is a disease of old age, in which the bones gradually become more porous (less dense), and weaker. The disease often remains undetected until a patient falls and fractures their wrist, hip or spine. People with low 'bone mineral density' (BMD) are more likely to develop the disease than those with a higher BMD. To look for genetic factors that might affect bone density, the deCODE team examined DNA samples from 207 Icelandic families with members affected by low BMD and bone fractures. In this way, they narrowed down their search to a region of the human genome that contained six known genes involved in bone development. One of these is BMP2, which makes a protein called bone morphogenetic protein-2. The researchers, lead by Unnur Styrkarsdottir, compared the BMP2 gene sequence in 188 osteoporosis patients with that present in samples from 94 unaffected people. They found that people who inherited one of three particular BMP2 variants were three times more likely to develop the disease.
deCODE was set up by scientist Kari Stefansson, to look for disease genes using DNA samples from the genetically-distinct Icelandic population. The country also has good genealogical and medical records, making family studies more straightforward. The researchers say they have confirmed the link between BMP2 and osteoporosis in the Danish population, as well as Iceland, and are currently carrying out a study of US women. 'This gene makes a growth factor that stimulates the formation of bone. When there's something wrong with it, the peak bone mass you develop before menopause is limited' said Stefansson. He said that a BMP2 gene test could be carried out on young women, and those at risk could then eat more foods with calcium, exercise more and begin to take medication early. A commercial genetic test based on the results of the study is being developed by the Swiss firm Roche Diagnostics, for sale early next year, the Independent newspaper reported.