Scientists find genetic origin of rare osteoporosis-causing disorder

Individuals who have Hajdu-Cheney syndrome, which is a rare, inherited disorder, are virtually guaranteed to develop severe osteoporosis. Now, an international team of geneticists and bone health experts reports having found the genetic sequence that causes the condition.

The key to the disease is a mutation in a short strip of DNA called the NOTCH2 sequence, which the team said appears to occur among nearly all of those with Hajdu-Cheney syndrome. In a recent issue of the journal Nature Genetics, researchers explained how they pinpointed this genetic origin.

Hajdu-Cheney syndrome is a rare and exceedingly serious condition. For the estimated 50 people in the world who have it, bone loss becomes a problem relatively early in life.

The syndrome causes a number of bone mineral-related problems. These include osteoporosis, excess flexibility of the bones, skull and facial deformities, tooth loss, hearing loss and vocal hoarseness, according to an article in the American Journal of Medical Genetics.

The investigators noted that this is the first concrete association between NOTCH2 and the syndrome. They added that NOTCH2 is believed to affect the rate of the creation of osteoclasts, which are specialized skeletal cells that break down bone minerals.

The discovery of the genetic cause of Hajdu-Cheney syndrome may have ramifications in the field of osteoporosis research, said the authors of the new study. They theorized that further study into the effect that genetics may have on osteoporosis risk may yield valuable insights for its diagnosis and treatment.

Osteoporosis, to which an individual can be genetically predisposed, is a widespread problem in the U.S. Around 10 million Americans suffer from the bone disease, according to the National Osteoporosis Foundation.

This figure is expected to rise to 14 million by the year 2020, based on the current rate change of osteoporosis diagnoses in the U.S. Besides genetics, environmental and lifestyle factors - such as calcium intake, smoking and exercise - have been found to have a significant impact on an individual's risk of developing osteoporosis.