Apparent monomorphism of ALDH2 in seven American Indian populations

Deficiency of mitochondrial aldehyde dehydrogenase (ALDH2) has been previously reported in South American Indians. We therefore assayed five individuals from each of five South American Indian populations (Quechua, Karitiana, Ticuna, Surui, Guahiba), and two North American populations (Maya and Moskoke) for the presence of the Oriental ALDH2(2) variant. These samples were also surveyed for other alleles altering ALDH2 function. Allele-specific amplification assay (ASA) did not detect the ALDH2(2) allele in any of the New World populations studied. The entire coding sequence of the ALDH2 cDNA was enzymatically amplified in partially overlapping fragments. Each fragment was digested using restriction endonucleases and subfragments 148-285 b.p. in length were analyzed by the single-stranded conformation polymorphism (SSCP) technique. No variants were detected within the coding region of the ALDH2 gene in any of the seven American Indian populations. Three potentially correct explanations for these results are suggested. First, an ALDH2 polymorphism is present but undetectable by SSCP; second, none of the studied individuals were ALDH2 negative; third, the polymorphism occurs beyond the coding region of ALDH2 gene.