WEDNESDAY, May 8 (HealthDay News) -- Mutations in a gene involved in bone development appear to cause certain severe forms of bone loss, a finding that could lead to new therapies for the common bone-thinning disorder osteoporosis, researchers report.
The mutations were found in a Swedish family with 10 members affected by a severe, early onset form of osteoporosis, as well as a Hmong family from Laos in which two sisters suffered from osteogenesis imperfecta.
Osteogenesis imperfecta, which is also known as brittle bone disease, affects six to seven out of every 100,000 people worldwide. The disease causes the bones to break easily, often from little or no trauma. There are four main forms, the most severe of which is fatal before or soon after birth.
The most common -- and mildest -- form is Type 1, in which most of a child's bone fractures happen before puberty. Some other problems, such as weak muscles and brittle teeth, are also possible.
Researchers have long known that about 90 percent of osteogenesis imperfecta cases are caused by a single mutation in one of two genes involved in making collagen, a fibrous protein in bone, skin and connective tissue.
It is only in the past decade, though, that the mystery behind the other 10 percent has become clearer, said Dr. Francis Glorieux, chairman of the Osteogenesis Imperfecta Foundation's medical advisory council.
The latest findings, published in the May 9 issue of the New England Journal of Medicine, underscore the role of a gene family known as WNT, said Glorieux, who was not involved in the research.
WNT genes make proteins called ligands, which means they latch onto receptors on the surface of body cells. Scientists have known that WNT is important in bone development and the upkeep of bone mass.
"But we haven't known which protein is key, which WNT ligand is actually doing the work. This
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