This syndrome has been associated with an increased risk of esophageal cancer in those who drink.[1] It has also been associated with lower than average rates of alcoholism, possibly due to its association with adverse effects after drinking alcohol.[2]
It is commonly thought that the flush reaction is caused by an inability to metabolize alcohol. To the contrary, around 80% of Asian people (less common in Thailand and India) have a variant of the gene coding for the enzyme alcohol dehydrogenase called ADH1B, and almost all Chinese and Korean people have a variant of the gene called ADH1C.[3] These genes result in an alcohol dehydrogenase enzyme which converts alcohol to acetaldehyde with a much higher efficiency than other gene variants (40 to 100-fold in case of ADH1B).[2] In about 50% of Asians, the increased acetaldehyde accumulation is worsened by another gene variant, the mitochondrial ALDH2 allele, which results in an inhibited acetaldehyde dehydrogenase enzyme, responsible for the breakdown of acetaldehyde.[3] The result is that affected people may be better at metabolizing alcohol, often not feeling the alcohol "buzz" to the same extent as others, but show far more acetaldehyde-based side effects while drinking.