CAMBRIDGE, United Kingdom ¿ Chiroscience Group plc, of Cambridge, said it has tracked down a gene that is directly responsible for controlling bone density, providing the company with a proprietary target from which to develop treatments for osteoporosis.

CEO John Padfield said, ¿At present, nothing can be done to restore the density of the bones of osteoporosis sufferers. Chiroscience now has its sights on a target that will lead to a drug that will restore bone loss.¿

The discovery was made by Chiroscience scientists in Seattle, in collaboration with Peter Beighton and Herman Hamersma at the University of Cape Town, South Africa. The bone mass gene is mutated in all patients suffering from sclerosteosis, a rare bone growth disorder, that causes bones to continue to gain mass throughout the affected individual¿s life. This results in a bone density many times greater than normal, making the bones almost impossible to break.

Sclerosteosis is known to occur with frequency only among Afrikaaners, a population of Dutch descent that settled in South Africa in the late 17th century. Among this group, 20,000 people ¿ or one in 160 individuals ¿ have one copy of the gene, which leads to a moderate increase in bone mineral density, while 29 are known to have two copies, which leads to excessive bone growth. Following four years of study of the genomes of affected individuals, Chiroscience has, over the past six months, fully characterized the gene and shown that in all patients with sclerosteosis it contains a mutation in a single DNA base pair. This mutation is believed to cause the gene to dysfunction and lead to an inability to correctly regulate bone growth.

Jeff Van Ness, one of the founders of the project, said, ¿This gene discovery is unique. It is a genetic surrogate for what we want a drug to do, which is to increase bone density. Now we know that bone density can be controlled ¿ this is the Holy Grail of bone mineral biology.¿

Padfield said it would be at least two years before Chiroscience would expect any candidates to enter clinical trials. ¿Identifying this target is an important first step in treating this silent disease. To put it in context, twice as many people in the U.S. have osteoporotic hip fractures as have heart attacks.¿

The share price rose by 7.5 pence to #2.54 when the discovery was announced on May 18. n