Frequency Distribution and Haplotypic Heterogeneity of β^E-Globin Gene among Eight Minority Groups of Northeast Thailand

Abstract

The frequencies of hemoglobin E and β^E-globin gene haplotypes were determined in eight minority groups living in the northeastern part of Thailand. A total of 478 samples of eight minority groups, namely Soui, Thai Khmer, So, Yor, Phuthai, Thai Puan, Thai Loei and Thai Dam, were examined. High prevalences of hemoglobin E (>50%) were observed in Soui, Thai Khmer, So, Yor and Phuthai inhabiting the region near Cambodia and Laos. Thai Puan, Thai Loei, Thai Dam and native Thai living in the same geographical area had prevalences of 42.6, 35.9, 21.4 and 27.9%, respectively. A prevalence of 9.5% was found among the Thai with Chinese background living in the same area. β-Globin gene haplotypes analysis demonstrated that most of the β^E-globin genes in these Thai populations were associated with two haplotypes: (– + – + + + –) and (+ – – – – + –) on chromosomes with framework 2 variety. Some β^E-globin genes in Soui and Thai Khmer groups were associated with the framework 3 chromosome. Genetic distances based on the β-globin gene haplotypes between minority groups revealed that Soui and Thai Khmer were closely related to each other. This finding has a valuable implication for study of the origin and spread of hemoglobin E in the region.

Strong linkage disequilibrium of a HbE variant with the (AT)9(T)5 repeat in the BP1 binding site upstream of the β-globin gene in the Thai population

“…The same haplotype has been reported in Chinese (Zhou et al 1995). Thus, HbE variants in the studied Thai population and Chinese may have the same origin (i.e., the HbE mutation may have occurred on a chromosome containing the (AT) 9 (T) 5 repeat and rapidly spread into Southeast Asia) although HbE variants with different origins are suggested to exist in Thailand (Fucharoen et al 2002). Assuming that the present relative allele frequencies of the (AT) x (T) y repeats on HbA chromosomes correspond to the frequencies of these repeats at the time of HbE mutation, (AT) 9 (T) 5 would have been one of the dominant alleles.…”

Population genetics of malaria resistance in humans

“…Although extensive sequence analysis has not been carried out, from examination of the haplotypic backgrounds for E alleles in northeast Thailand, more than one mutational origin (Fucharoen et al, 2002) is suggested. However, the E allele found in China is on the same haplotype as that found in Thailand (Ohashi et al, 2005), suggesting that it does not have a different origin.…”

The Diverse Molecular Basis and Hematological Features of Hb H and AEBart’s Diseases in Northeast Thailand

“…In this paper, we describe the molecular basis and phenotype-genotype correlation in patients with Hb H and AEBart’s diseases of northeast Thai descent with a high prevalence of Hb E [17]. Unlike other populations in which the Hb H disease is much more frequently due to deletions than nondeletion mutations [18, 19, 20, 21, 22, 23, 24], as shown in table 1, the Hb H disease in this group of the Thai population most commonly (35 of 52 cases, 67.3%) results from the combination of α-thalassemia 1 (SEA) and Hb CS (–– SEA /α CS α) and less commonly (14 of 52 cases, 26.9%) from the interaction of α-thalassemia 1 (SEA) and deletional α-thalassemia 2 (–– SEA /–α).…”