Facial flushing in a 22-year-old ALDH2 heterozygote before (left) and after (right) drinking alcohol. Approximately 36% of East Asians (Japanese, Chinese, and Koreans) show a characteristic physiological response to drinking alcohol that includes facial flushing, nausea, and tachycardia. This so-called alcohol flushing response (also known as “Asian flush” or “Asian glow”) is predominantly due to an inherited deficiency (rs671) in the enzyme aldehyde dehydrogenase 2 (ALDH2). Clinicians and the East Asian public generally know about the alcohol flushing response. (The individual pictured in this figure has given written consent for publication of his picture using the PLoS consent form.)