LONDON, Sept. 12 (Xinhua) -- An international team of scientists have discovered a genetic mark that increases the risk for primary open-angle glaucoma, which is the most common form of glaucoma and a major cause of blindness worldwide.
The team, which includes scientists from Iceland, China, Sweden, the UK and Australia, analyzed genetic information of more than 40,000 people in those countries, and reported the discovery in the journal Nature Genetics on Sunday.
The genetic mark is a single-letter variation (SNP) on the chromosome 7q31 in the human genome. A SNP is a smaller unit than gene in genetics. And the location of that SNP is near genes CAV1 and CAV2, which encodes membrane proteins that are involved in the process of glaucoma.
It is found that the SNP is common among Europeans, with approximately 6 percent of people of European ancestry carrying two copies of the at-risk version, putting them at roughly 60 percent greater risk of developing the disease than those Europeans who carry none.
But among Chinese, the impact of the SNP is markedly different. In study groups from Hong Kong and Shantou, the at-risk version of the SNP is shown to be carried by less than 1 percent of the population, but just one copy carried confers a more than five-fold increase in risk than the Chinese who carry none.
"This (difference) is perhaps the most intriguing aspect of this discovery", said Dr. Kari Stefansson, the senior author of the study and the Executive Chairman and President of Research of deCODE, which is an Icelandic company specializing in genetics.
Stefansson told Xinhua that the reason of that difference is not clear yet, but the discovery is important because we can fold them directly into tests to target screening and to detect and treat glaucoma in an earlier stage.
"This discovery in glaucoma has, in my view, a direct and important application for testing people of Chinese ancestry, as there is 1% of the population who should be screened regularly for glaucoma once they reach middle age."
Primary open-angle glaucoma is a disease in which the optic nerve becomes damaged, leading to a progressive loss of sight. It affects tens of millions of people worldwide, mostly those over the age of 50. The key to treat this disease is early diagnosis and treatment to slow the loss of sight.