Wednesday, October 01, 2003

Reuters - Gene Difference May Explain SARS Epidemic

This is really quite interesting news, and I'd like to see if it holds up under further study:

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.


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.

I chose to highlight that last line because it unintentionally betrays the blinkered worldview many people in East Asia seem to have about that portion of humanity that isn't white and Western1. The world doesn't consist of East Asians and Europeans alone, though one would never guess it from this statement. How common is this allele amongst other populations, like Arabs, Indians and even (the horror!) Africans? Fortunately, we don't have to rely on just this particular team of Taiwanese researchers for the information we require. It appears, from the few other references to this allele that I've been able to find, that HLA-B 4601 is actually specific to the East Asian region, so if the study holds up, the rest of us should have nothing to fear.

Update: Here's a Taiwanese government news report that confirms the region-specific nature of this allele.

1 - This is no mere unfounded stereotype. Many East Asians seem to subscribe to some sort of "Great Chain of Being" notion of racial heirarchy, with their own countrymen at the very top, or, at worst, slightly below white people, and everyone else coming after, in descending order of worth as skin hue darkens. This becomes very apparent to any non-white foreigner who steps foot in an East Asian country.