Gene Mutation Linked to Increased Liver Disease Risk

Aldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme responsible for detoxifying harmful aldehydes, including acetaldehyde and acrolein. Acrolein, a highly reactive aldehyde produced from environmental pollutants such as cigarette smoke, poses significant health risks by damaging proteins, DNA, and lipids, contributing to various diseases, including cardiovascular issues and neurodegeneration.

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A research team led by Associate Professor Takeshi Izawa and graduate student Yuki Takami from the Graduate School of Veterinary Science at Osaka Metropolitan University conducted a study using knock-in mice to mimic the dysfunction of the ALDH2 enzyme found in human carriers of the ALDH2*2 gene variant. The study revealed that exposure to allyl alcohol, which metabolizes into acrolein in the liver, resulted in a rapid increase of multiple aldehydes in the blood, a phenomenon termed an "aldehyde storm." This accumulation led to severe liver damage, particularly in individuals with the ALDH2*2 variant.

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The research indicated that the detoxification process typically facilitated by glutathione was severely impaired in the mice, leading to significant depletion of this antioxidant in the liver. This depletion was associated with increased oxidative stress and subsequent ferroptosis, a form of cell death. The liver exhibited the most extensive tissue damage, highlighting the critical role of aldehyde metabolism and redox balance in liver health.

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Individuals carrying the ALDH2*2 gene variant have a diminished capacity to metabolize aldehydes from alcohol, certain foods, and environmental chemicals. The study suggests that these individuals are at heightened risk for liver injury due to the overwhelming aldehyde levels, particularly during acute exposure. The findings underscore the necessity for ALDH2*2 carriers to avoid high aldehyde exposure, maintain a healthy diet to support their antioxidant systems, and monitor their liver health closely.

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Takeshi Izawa noted the study's implications, stating, “The exposure level of acrolein used in this study clearly exceeds that of smoking; therefore the risk of severe liver damage like that reported in this paper occurring by smoking only is low.” He further emphasized that patients receiving anticancer drugs, such as cyclophosphamide, which metabolizes to acrolein, may face increased risks.

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The researchers plan to explore additional health effects of chronic aldehyde exposure in ALDH2*2 carriers, particularly its potential links to cancer. Izawa remarked, “Acrolein is also found in electronic cigarette smoke and as a metabolite of anticancer drugs,” indicating a broader concern for health risks associated with daily aldehyde exposure in this population.

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• “We identified for the first time the close relationship among aldehyde metabolism, redox balance, and the ferroptosis pathway,” — Yuki Takami, Graduate Student

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• “Going forward, we plan to investigate other health effects of chronic exposure to aldehydes in ALDH2*2 carriers, particularly their involvement in cancer.” — Takeshi Izawa, Associate Professor

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This research highlights the critical intersection of genetics, environmental exposure, and liver health, particularly for those with the ALDH2*2 gene variant.

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