Health-related follow up: can Asians drink? (UPDATED)

The latest installment of the Doing Business in China series talked about the ritual of drinking-to-the-point-of-drunkness in formal Chinese "business" gatherings. This doesn't always happen, but it happens enough to be a factor in professional life. In my experience, it was even more common in the provinces than in the big cities, and most likely in "getting to know you" dinners involving big delegations. Now a reader in Philadelphia writes with a question about the practice:

"I read your post on Doing Business in China, and I wondered to what extent the prevalence of alcohol in after-hours business gatherings is complicated by the alcohol flush reaction common to so many people of East Asian descent.  I am an American of Chinese descent with this particular genetic variation and I find that the unpleasant side effects of alcohol consumption interfere with any desire to drink until intoxication.  Given the frequency of this condition, do business people in China simply accept the situation as normal or is there a demurral from overconsumption, where someone may take one drink as a courtesy and then decline politely thereafter, so as to avoid such intoxicating effects?"

The issue here involves an enzyme called acetaldehyde dehydrogenase, or ALDH2. It is part of the metabolic chain for breaking down alcohol, and people who lack it are subject to a kind of "alcohol poisoning." Their face and/or neck turns red, they sweat, they flush and may pass out. Interestingly (and to the best of my understanding), the anti-alcoholism drug Antabuse, which is supposed to make drinking so unpleasant that people are forced to swear off, works by mimicking the effect of a blocked ALDH2 enzyme.

Caucasians rarely lack this enzyme, but as many as half the people do among some East Asian and North Asian population groups -- Japanese, Chinese, Koreans, Mongolians, many Native American groups in the US and Canada. (I don't know about Africans, South Asians, etc.) So at a drinking party in China, you'll typically see some faces turn bright red after a couple of sips.
 
How do people who have this problem cope? Obviously it depends, but I've seen two main patterns. Some people politely avoid the baijiu or similar high-proof spirits. They stick to tea or hot water or soft drinks. Others plunge right ahead, as if getting drunk is the point (to promote a shared dropping of inhibitions). It's tough work but must be done. Whenever I felt sorry for myself at these rituals, I realized that there were people who were facing even greater challenges. 干杯 - Ganbei!

UPDATE: thanks to reader M.L. a map from a paper in the Annals of Human Genetics showing with dark shade the prevalence of the genetic problem in question. Centered farther south in China than I would have guessed. Mongolia not very much affected. As for adjoining areas, M.L. reports "Central Asians - and I can back this up from direct observation, especially in former Soviet Central Asia, most certainly do not seem to be afflicted with any symptoms of alcohol allergies."