Refined geographic distribution of the oriental ALDH2*504Lys (nee 487Lys) variant.
Level 4 - case-series / case-control
Cross-sectional population genetic frequency survey combining new samples with published data
PubMed 19456322 · doi:10.1111/j.1469-1809.2009.00517.x
What was done
The authors mapped the global geographic distribution of the mitochondrial aldehyde dehydrogenase variant ALDH2*504Lys (previously known as 487Lys). They generated new genotyping data on 4,091 individuals across 86 population samples and synthesized published allele frequency data covering 80,691 individuals across 366 population samples (totaling 84,782 individuals from 452 population samples).
What was found
The ALDH2*504Lys allele was essentially absent in all world regions outside East Asia. Within East Asia, the highest allele frequency centered in Southeast China and declined radially across China, Japan, Korea, Mongolia, and Indochina. Indigenous populations in South China exhibited much lower allele frequencies than southern Han Chinese migrants from Central China, supporting the conclusion that the allele was dispersed through Han Chinese expansion. The abstract provides sample counts but does not report exact numerical allele frequencies or gradient percentages.
Why it matters
This high-resolution geographic map clarifies the origin and historical spread of a clinically important metabolic variant that alters acetaldehyde metabolism, impacts alcoholism risk, and influences susceptibility to esophageal and colorectal cancers.
Limits
The abstract reports aggregated population data without presenting specific quantitative allele frequencies, confidence intervals, or formal statistical testing for the correlation between ALDH2*504Lys distribution and esophageal cancer incidence. Potential sampling biases across the hundreds of aggregated published studies were not detailed.
Cited by
- supports Many Han Chinese individuals lack or have low levels of the enzyme that breaks down acetaldehyde into acetic acid during alcohol metabolism, making alcohol consumption less pleasant and specifically lowering their risk for alcoholism.