ALDH2 gene spans 46031 base pairs (bp), consists of 13 exons and 12 introns and is located on the (+) DNA strand.

The ALDH2 mRNA consists of 1989 base

The ALDH2 protein is 517 amino acid long, has a molecular weight of 56 Kd, and forms a homotetramer.

ALDH2 is expressed in several human tissues with the highest levels found in liver. Screening of human cDNA libraries has revealed that ALDH2 transcripts are present in human liver, kidney, heart, stomach, colon, muscle, ovary, pancreas, lung, prostate, ear, eye, marrow, gall bladder, testis, thyroid, retina, adipose, adrenal gland, blood, brain, breast, placenta, uterus, B-cells, fetal brain, tonsil, foreskin, nervous normal and also in lung tumor, bladder tumor, nervous tumor.

Mitochondrial matrix

Conversion of aldehydes to acids via the reaction: ALDEHYDE + NAD + H2O = ACID + NADH

ALDH2 belongs to the aldehyde dehydrogenase gene superfamily .

One of the most studied polymorphism is a single base-pair mutation (1510 GA) in exon 12 of ALDH2 gene that causes an E487K substitution (ALDH2*2 allele), which results in catalytic inactivation of the enzyme. The ALDH2*2 allele is dominant negative and is responsible for acute alcohol intoxication due to accumulation of acetaldehyde. Facial flushing, nausea, dizziness and tachycardia characterize this alcohol intoxication. The ALDH2*2 allele is frequent in, but confined to Asian individuals, and it appears to be a determinant against alcoholism. On the other hand, alcohol-drinking individuals having the ALDH2*2 genotype are at substantially high risk of developing esophageal and upper aerodigestive tract cancers, head and neck cancers, colorectal cancer.