Alcohol Dehydrogenase is NOT the issue in "Asian Flush"... the deficiency is in Aldehyde Dehydrogenase. Acetaldehyde is an irritant of the skin, eyes, mucous membranes, throat and respiratory tract. Symptoms of exposure to this compound include nausea, vomiting, headache, and large doses can even cause death by respiratory paralysis. It may also cause drowsiness, delirium, hallucinations and loss of intelligence. Exposure may also cause severe damage to the mouth, throat and stomach; accumulation of fluid in the lungs, chronic respiratory disease, kidney and liver damage, throat irritation, dizziness, reddening and swelling of the skin.
In the "normal" liver, Alcohol Dehydrogenase will convert Ethanol into Acetaldehyde, then Aldehyde Dehydrogenase will convert Acetaldehyde into Acetic Acid (completely harmless vinegar). Many East Asians carry a dominant genetic mutation, and the "Asian Flush" liver converts Ethanol into Acetaldehyde... and then is unable to convert the highly toxic Acetaldehyde into Acetic Acid.
In a regular drinker, large quantities of Ethanol have to be ingested in order for the person to experience the effects of Acetaldehyde poisoning since the "normal" human liver is able to convert it to Acetic Acid, the person must drink at a much faster rate than their liver converts.
In a person with the "Asian Flush" mutation, Acetaldehyde poisoning is immediate and prolonged, and triggered by essentially any amount of alcohol. Even 1 shot-glass full of white wine can trigger the entire list posted above of dangerous symptoms.
A person cannot suddenly DEVELOP this genetic mutation, you are BORN with it, or not. Certain drugs such as disulfiram (Antabuse) can impair a "normal" liver's ability to produce Acetaldehyde. Also, other developed illnesses or liver problems could cause a sudden, or later-life onset of symptoms similar to "Asian Flush". However, often the development is an inability to drink AS MUCH, or CERTAIN TYPES of alcoholic beverages... and this IS NOT the same issue as "Asian Flush" reaction. Trust me, I have "Asian Flush" reaction, and even 1 thimble-full of hard liquor causes me immediate Acetaldehyde poisoning, and it is something that currently CANNOT BE TREATED OR CURED. Gene therapy is essentially the only hope. In the meantime, fellow "Asian Flush" sufferers, please DO NOT DRINK ALCOHOL. Even moderate drinking in us can cause Cirrhosis of the Liver, Stomach Cancer, Colon Cancer, and a host of other problems. Acetaldehydes are NOT TO BE TAMPERED WITH. I drink cranberry juice with seltzer water at the bar. Be smart, Asian kids, study your Chemistry and save your lives!