A rare and incurable endemic bone disease is posing a grave health risk to residents in a remote Tibetan region, with about 170,000 people threatened by it.

At least 14,662 people have been diagnosed with Kaschin-Beck disease in 11 counties in Qamdo prefecture, one of the most seriously affected regions, according to a survey conducted by local health authorities.

The survey said an estimated 1.70 lakh people stand at risk by the disease.

The patients afflicted by the disease develop thick and deformed joints, which eventually prevents them from working, official news agency reported today.

Doctors say the cause of the disease remains unknown.

Some suspect that a fungus contained in barley, a staple food in the plateau, is to blame for it. Low iodine intake may be another cause, experts say.

The local government has been promoting relocation as a way to prevent the spread of the disease.

In the past five years, about 90 million yuan (USD 13. 55 million) has been spent on the relocation programme and nearly 20,000 residents have been moved out of the region, it said.