Refined Geographic Distribution of the Oriental ALDH2*504Lys (nee 487Lys) Variant
- Alternative Author(s)
- Lee, Mi Young
- Issued Date
- Mitochondrial aldehyde dehydrogenase (ALDH2) is one of the most important enzymes in human alcohol metabolism.
The oriental ALDH2
504Lys variant functions as a dominant negative, greatly reducing activity in heterozygotes and
abolishing activity in homozygotes. This allele is associated with serious disorders such as alcohol liver disease, late
onset Alzheimer disease, colorectal cancer, and esophageal cancer, and is best known for protection against alcoholism.
Many hundreds of papers in various languages have been published on this variant, providing allele frequency data for
many different populations. To develop a highly refined global geographic distribution of ALDH2
collected new data on 4,091 individuals from 86 population samples and assembled published data on a total of 80,691
individuals from 366 population samples. The allele is essentially absent in all parts of the world except East Asia.
504Lys allele has its highest frequency in Southeast China, and occurs in most areas of China, Japan,
Korea, Mongolia, and Indochina with frequencies gradually declining radially from Southeast China. As the indigenous
populations in South China have much lower frequencies than the southern Han migrants from Central China, we
conclude that ALDH2
504Lys was carried by Han Chinese as they spread throughout East Asia. Esophageal cancer,
with its highest incidence in East Asia, may be associated with ALDH2
504Lys because of a toxic effect of increased
acetaldehyde in the tissue where ingested ethanol has its highest concentration. While the distributions of esophageal
cancer and ALDH2
504Lys do not precisely correlate, that does not disprove the hypothesis. In general the study of
fine scale geographic distributions of ALDH2
504Lys and diseases may help in understanding the multiple relationships
among genes, diseases, environments, and cultures.
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