Facial flushing after alcohol consumption in a 21-year-old woman suggests a mutation in which enzyme?

Facial flushing after alcohol consumption is commonly associated with a deficiency or mutation in the enzyme aldehyde dehydrogenase, particularly in individuals of certain Asian backgrounds. When alcohol is consumed, it is first metabolized to acetaldehyde by alcohol dehydrogenase. Normally, acetaldehyde is then rapidly converted to acetic acid by aldehyde dehydrogenase. However, if there is a mutation in the aldehyde dehydrogenase enzyme, acetaldehyde accumulates in the body, leading to various effects, including flushing, palpitations, and even nausea.

This reaction is part of a pathway that explains the adverse effects experienced by individuals with this mutation. Accumulation of acetaldehyde, a toxic byproduct of alcohol metabolism, triggers the release of histamines and causes vasodilation, resulting in noticeable facial flushing. Thus, the facial flushing experienced by the 21-year-old woman indicates an issue with the metabolism of acetaldehyde rather than the initial conversion of alcohol itself.