Plenty of folks get a bit red in the face this time of the year. The cheeks of those who live in northern climes may take on a certain glow when they walk the dog or take out the garbage on a brisk, windy night. The same appearance bedevils folks in warmer climes should they forget to apply sunblock before settling beside the pool.
An altogether different group includes fully one third of all people of East Asian descent, who have been born with a genetic deficiency that causes their cheeks, and often their necks, arms and trunk to turn sunburn-red after consuming even small amounts of alcohol (see picture).
The condition is known colloquially as “Asian Flush” or “Asian Glow.” It is often associated with nausea, headache and tachycardia, and is caused by an inherited deficiency of aldehyde dehydrogenase 2 (ALDH2), one of 2 key enzymes involved in the metabolism of alcohol.
Unfortunately, Asian Flush isn’t as benign as once thought. Scientists have determined in recent years that ALDH2 deficiency is a risk factor for esophageal cancer, which happens to be one of the deadliest cancers humans can get.
Philip Brooks and colleagues at the National Institute on Alcohol Abuse and Alcoholism published a seminal article on this association in 2009. In it, the scientists explained that the first of those 2 key enzymes transforms alcohol into acetaldehyde, a vasodilator in the short term and a carcinogen in the long term. The second enzyme, ALDH2, converts that toxin into acetate, a harmless chemical.
People who lack ALDH2 experience a build-up of acetaldehyde in the body after they consume alcohol. The short-term effect of the build-up is the Asian Flush.
But that’s not what prompted Brooks to write that article. “People with this ALDH2 deficiency have a really high risk of getting esophageal cancer when they drink alcohol,” he explained to the LA Times. “Anyone who drinks is at risk, but the more you drink, the more your risk goes up. And when you’re ALDH2-deficient, your risk goes up much more dramatically.”
How dramatically? Brooks cites studies showing that people who inherit a deficient gene from one parent and who consume just 2 alcoholic beverages per day are nearly 10 times more likely to develop esophageal cancer than those with the same alcohol intake but who are in possession of 2 normal copies of the ALDH2 gene.
The problem is huge, because so many people are affected. Brooks and others estimate there are about 540 million ALDH2-deficient individuals in the world. That’s 8% of the world’s population.
The only good news in this story is that ALDH2 deficiency isn’t asymptomatic. People who get Asian Flush know all about their affliction, so screening tests aren’t required. If these folks can be reminded to look at their syndrome as a red flag for an increased risk of a very bad cancer, they can perhaps be convinced to avoid alcohol altogether.