Alcohol intolerance

Alcohol intolerance

The Alcohol Flushing Response

Alcohol intolerance is a condition in which the body is unable to properly metabolize alcohol, leading to various adverse reactions. This condition is often due to a genetic deficiency in the enzyme aldehyde dehydrogenase 2 (ALDH2), which is crucial for the breakdown of acetaldehyde, a toxic byproduct of alcohol metabolism.

Pathophysiology

Biotransformation pathway of ethanol

When alcohol is consumed, it is first metabolized in the liver by the enzyme alcohol dehydrogenase (ADH) into acetaldehyde. Acetaldehyde is then further metabolized by ALDH2 into acetic acid, which is non-toxic and can be further broken down into water and carbon dioxide. In individuals with alcohol intolerance, the ALDH2 enzyme is deficient or inactive, leading to the accumulation of acetaldehyde in the blood.

Symptoms

The accumulation of acetaldehyde causes a range of symptoms, including:

• Facial flushing
• Nausea
• Headache
• Rapid heartbeat
• Hypotension

These symptoms are collectively known as the "Alcohol flushing response" and are most commonly observed in individuals of East Asian descent, where the inactive form of ALDH2 is more prevalent.

Genetics

Molecular Structure of ALDH2

The genetic basis of alcohol intolerance is primarily linked to a single nucleotide polymorphism (SNP) in the ALDH2 gene. This SNP results in an amino acid substitution that renders the enzyme inactive. The inactive variant, known as ALDH2*2, is inherited in an autosomal dominant manner, meaning that even one copy of the defective gene can lead to symptoms of alcohol intolerance.

Diagnosis

Diagnosis of alcohol intolerance is typically based on clinical symptoms and family history. Genetic testing can confirm the presence of the ALDH2*2 allele. It is important to differentiate alcohol intolerance from other conditions such as alcohol allergy or alcohol use disorder.

Management

The primary management strategy for alcohol intolerance is avoidance of alcohol consumption. There is currently no cure for the condition, and treatment focuses on managing symptoms when accidental exposure occurs. Antihistamines may help alleviate some symptoms, but they do not address the underlying cause.

Related pages

• Aldehyde dehydrogenase
• Alcohol dehydrogenase
• Acetaldehyde
• Alcohol allergy

Gallery

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  ALDH2 Varied SNP

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  The Alcohol Flushing Response

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  Biotransformation pathway of ethanol

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  Molecular Structure of ALDH2

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  ALDH2 Varied SNP