Molecular analysis of haemoglobin E in Southeast Asian populations.

Haemoglobin (Hb) E is the most common Hb variant in Asia where its gene frequency approaches 0.3 in some areas. We studied genetic background of Hb E genes among Southeast Asian populations. This study examined β-globin gene haplotypes linked to haemoglobin E (Hb E) in diverse groups of Southeast Asian populations. The study was conducted on southern Thai (22 alleles), Cambodian (84 alleles), Laotian (120 alleles), Vietnamese (87 alleles) and Burmese (one allele) subjects. Results were compared with those of previous studies in northeast Thailand, the Yunnan of China, West India and Europe. Ten different haplotypes were observed. The four most common haplotypes were haplotypes 1 (- + - + + + -) and 2 (+ - - - - + -) on chromosomes with framework 2 and haplotypes 6 (- + - + + - +) and 7 (+ - - - - - +) on chromosomes with framework 3 variety. Phylogenetic analysis indicated that haplotype 1 is a relatively recent haplotype found in all populations, whereas haplotype 6 is found predominately in Cambodians. The results indicate that at least two genetic origins of Hb E are responsible for the high prevalence and spread of Hb E among Southeast Asian populations.