Addendum: Terminology Clarification for Alcohol Flush Reaction (AFR) and ALDH2 Deficiency
This visual summary is provided to clarify terminology used in the literature regarding Alcohol Flush Reaction (AFR) and to distinguish the symptom -based term from the underlying genetic condition, ALDH2 Deficiency, and its
Figure A1. Terminology clarification and mechanistic overview of Alcohol Flush Reaction (AFR) and ALDH2 Deficiency
Alcohol Flush Reaction (AFR) is a symptom based term describing visible physiological responses associated with acetaldehyde accumulation. The underlying cause is ALDH2 Deficiency, a genetic condition characterized by reduced aldehyde dehydrogenase 2 activity, most commonly associated with ALDH2*2 variant. Impaired ALDH2 activity results in decreased acetaldehyde clearance, leading to acetaldehyde accumulation and increased downstream demand on endogenous glutathoric dependent pathways.
Sources: Edenberg, 2007, Chen et al, 2009, Wu et al, 2023, Chen et al, 2026, Takami et al, 2025