Reminder: polymorphic enzyme responsible for the oxidation of aldehydes to carboxylic acids. It is found in many tissues of the body, but the highest concentration is in the liver.

There are 19 divided into 4 subgroups, ALDH1 to ALDH4:

• ALDH1: ALDH1A1  (9q21.3),  ALDH1A2  (15q21.3),  ALDH1A3  (15q26.3),  ALDH1B1  (9p13.1),  ALDH1L1  (3q21.3),  ALDH1L2(12q23.3)
• ALDH2 (mitochondrial): ALDH2  (12q24.12)
• ALDH3A1 (17p11.2), ALDH3A2  (17p11.2),  ALDH3B1  (11q13.2),  ALDH3B2  (11q13.2)
• ALDH4A1 (1p36.13), ALDH5A1  (6p22.3),  ALDH6A1 (14q24.3),  ALDH7A1  (5q23.2),  ALDH8A1  (6q23.3),  ALDH9A1  (1q24.1),  ALDH16A1 (19q13.33),  ALDH18A1(10q24.1)

Aldehyde dehydrogenase 2 is a mitochondrial enzyme found mainly in the liver and digestive mucosa. It oxidizes aldehydes which are potentially carcinogenic and allows the transformation of ethanol into acetic acid. There are variants of the ALDH2 gene: one is present in Asians (50 % in Vietnam and Taiwan) resulting in a decrease in the activity of the enzyme and intolerance to alcohol intake (quickly drunk). Associated with an increase in the activity of alcohol dehydrogenase (which turns alcohol into ethanol) in the same population, it causes Asian reddening syndrome, commonly called Asian flush or Asian glow, that is, the appearance of  erythema of the face, neck, shoulders, or in some cases, the whole body after consuming alcohol. This reaction is the result of an accumulation of acetaldehyde. This is equivalent to the antabuse effect observed after taking alcohol in patients treated with disulfiram (an aldehyde dehydrogenase inhibitor).

Anesthetic implications: 

not known; keep that in mind in case of unusual reaction following the injection of alcohol (sclerosis of venous or lymphatic malformations)

References:

-        Poupon RE, Nalpas B, Coutelle C, Fleury B, Couzigou P, Higueret D. (1992) 
Polymorphism of alcohol dehydrogenase, alcohol and aldehyde dehydrogenase activities: implication in alcoholic cirrhosis in white patients.  
Hepatology 1992 ; 15 : 1017–22

Updated: December 2021