Study: Gene Difference May Explain SARS Epidemic

Reuters News

Wed October 1, 2003 12:11 PM ET

By Maggie Fox, Health and Science Correspondent

WASHINGTON (Reuters) - A genetic susceptibility may explain why SARS raged last year in southeast Asia and nowhere else in the world outside of Toronto, Taiwanese researchers reported this week.

They found a certain variant in an immune system gene called human leukocyte antigen, or HLA, made patients in Taiwan much more likely to develop life-threatening symptoms of SARS.

The gene variant is common in people of southern Chinese descent, the team at Mackay Memorial Hospital in Taipei reported.

Their finding, published in an online journal, BMC Medical Genetics, must be confirmed by independent researchers. But the Taiwanese team said the genetics could explain the puzzling distribution of SARS last year.

"After the outbreak of SARS coronavirus infection in the Guangdong Province of China, it was surprising to observe that the spreading of the disease was mostly confined among southern Asian populations (the Hong Kong people, Vietnamese, Singaporeans and Taiwanese)," they wrote.

Severe Acute Respiratory Syndrome first arose in Guangdong last November. It spread to Hong Kong, Vietnam, Beijing and Singapore, and was transported around the world by airliner. SARS eventually was suspected of affecting 8,098 people and killing 774, according to the World Health Organization's latest figures.

The flu-like disease is caused by a virus from a family known as coronaviruses. They cause diseases in livestock and some cases of the common cold in people.

The SARS coronavirus is unique genetically but similar versions have been found in animals sold in Chinese food markets.

Marie Lin, Chun-Hsiung Huang and colleagues examined the HLA gene in 37 cases of probable SARS, 28 fever patients excluded later as probable SARS, and 101 non-infected health care workers who were exposed or possibly exposed to SARS coronavirus.

"An additional control set of 190 normal healthy unrelated Taiwanese was also used in the analysis," they wrote in their report.

They found that patients with severe cases of SARS were likely to have a version of the HLA gene called HLA-B 4601.

They noted that no indigenous Taiwanese, who make up about 1.5 percent of the population, ever developed SARS. HLA-B 4601 is not seen among indigenous Taiwanese, they noted.

"Interestingly, (HLA-B 4601) is also seldom seen in European populations," they added.