The absence of which compound leads to symptoms of alcohol flush reaction?

The alcohol flush reaction is primarily related to the accumulation of acetaldehyde, a toxic byproduct of alcohol metabolism. Specifically, when alcohol is consumed, it is converted to acetaldehyde by the enzyme alcohol dehydrogenase. Normally, acetaldehyde is then quickly converted to acetic acid by another enzyme called aldehyde dehydrogenase (ALDH). In individuals with a deficiency in ALDH, acetaldehyde accumulates in the body, leading to symptoms such as facial flushing, nausea, increased heart rate, and other discomforts commonly associated with the alcohol flush reaction.

In contrast, other options presented do not directly contribute to this reaction in the same way. For example, acetic acid is a product of acetaldehyde metabolism, and the presence of ethyl alcohol is simply the original substance being metabolized; neither of these compounds leads to the flush reaction. Aldehyde oxidase is an enzyme that metabolizes different aldehydes, but it does not play a significant role in the process of acetaldehyde clearance that directly influences symptoms of the flush reaction.

Thus, the absence of adequate levels of acetaldehyde metabolism due to a deficiency in the ALDH enzyme leads to its accumulation, which is the primary reason behind