Iceland DNA study reveals key gene in osteoporosis

A study of Icelandic families has identified a gene that could play a decisive role in osteoporosis, the bone-wasting disease that affects an increasing number of elderly women.

A study of Icelandic families has identified a gene that could play a decisive role in osteoporosis, the bone-wasting disease that affects an increasing number of elderly women.

People who inherit a variation of the gene are three times more likely to develop osteoporosis, which is characterised by brittle bones which fracture easily.

Scientists for deCODEgenetics, the Icelandic company which carried out the research, said that they hope to develop a test that will identify people at highest risk of the disorder in later life.

One possibility is that those with a genetic predisposition to develop osteoporosis could decrease the risk by having more exercise or eating a diet rich in calcium, which is essential for bone development.

Osteoporosis is especially common in post-menopausal women who experience a gradual erosion of bone density, making them vulnerable to fractures. Although there is a strong genetic component to osteoporosis, previous claims to have found the "gene for osteoporosis" have not stood up to scrutiny.

Now the deCODE team claims to have found a gene heavily implicated in the disorder by examining 207 Icelandic families with at least one member who has low bone density and bone fractures. The gene is called BMP-2, which stands for bone morphogenetic protein-2, and lies on chromosome 2, one of the 23 pairs of human chromosomes in which the DNA of the human genome is packaged.

A spokesman for deCODE said a study of Danish women with osteoporosis has confirmed the likely role that the gene plays in helping to trigger the bone disorder in women. "Taken together, these results make a strong case for genetic variations of BMP-2 as risk factors for osteoporosis," he said.

Dr Kari Stefansson, chief executive of deCODE, said that a test to identify people with specific variants of the gene is being developed by the giant Swiss company Roche Diagnostics, and will be available early next year.

The BMP-2 gene exists in different versions. Three of these variations are thought to increase the risk of osteoporosis since 30 per cent of patients had one or other of them.

Dr Stefansson said that carrying one of these variations of the gene does not guarantee that someone will develop osteoporosis, but it increases that risk three times.

Scientists at deCODE have taken advantage of Iceland's extensive genealogical records, dating back 1,000 years to when the island was first colonised by Vikings. This allows them to identify precise relationships between families.

Icelandic people are not genetically diverse compared with other populations in the world, but Dr Stefansson said the study was still relevant.

It was published in an online journal, The Public Library of Science.