Experts scan disease links with Chinese "gene map"

People hold a Chinese national flag ahead of a raising-flag ceremony during a photo call at Yangren Street in Chongqing Municipality, September 29, 2009.

HONG KONG (Reuters) - A large analysis of the genes of 8,200 ethnic Chinese has revealed subtle genetic differences between inhabitants in northern China and southern China, and even between different Chinese dialect groups.

Published in the American Journal of Human Genetics, the study is important as scientists are trying to identify if certain gene variants may render some people more vulnerable to some diseases -- so that targeted preventive measures can be taken and therapies may one day be found.

Led by Liu Jianjun, head of the human genetics group at the Agency for Science, Technology and Research in Singapore, the researchers found that inhabitants in northern China were genetically distinguishable from those in the south, a finding that was consistent with historical migration patterns in China.

Consistent genetic differences, or variants, showed up in 0.3 percent of the genes between both groups, Liu said.

"From this genetic map, it tells us how people differ from each other, or how people are more closely linked to each other," Liu told Reuters in a telephone interview.

"We don't know what these variants are responsible for. Some may have clinical outcomes and influence disease development. That is why we are interested in genetic variation. That will help us understand when we do disease studies."

The huge sample of 8,200 ethnic Chinese participants were drawn from 10 Chinese provinces and Singapore.

Interestingly, the scientists also found genetic variants between different Chinese dialect groups.

"Different dialect groups are definitely not identical ... language is a reflection of our evolution, that's why you see the differences," Liu said.

The team has since moved on to try to establish if these gene variants may be linked to the tendency among certain groups of Chinese to develop particular diseases -- such as nasopharyngeal cancer, which is more prevalent among southern Chinese, but not Chinese in northern provinces.

The team appears to have made some headway with two chronic autoimmune diseases - psoriasis and systemic lupus erythematosus (SLE).

Psoriasis causes red scaly patches on the skin, while SLE is a connective tissue disease that often harms the heart, joints, skin, lungs, blood vessels, liver, kidneys and nervous system.

"We looked (at genes of) 1,000 psoriasis patients and 1,000 people without the disease. Those with psoriasis had particular genetic variants in three positions that we identified," Liu said.

"These variants are very common in patients and very rare in non-patients. We look at where these variants are located and we are able to nail the genes, and the genes can provide information why certain people develop this disease."

(Editing by Victoria Main)