Increased HbF levels or F-cell (HbF containing erythrocyte) numbers can ameliorate the disease severity of β-thalassemia major and sickle cell anemia. Recent genome wide association studies reported that single nucleotide polymorphisms (SNPs) in BCL11A gene on chromosome 2p16.1 were correlated with F-cells among healthy northern Europeans, and HbF among Sardinians with β-thalassemias. In this study, we showed that SNPs in BCL11A were associated with F-cell numbers in Chinese with β-thalassemia trait, and with HbF levels in Thais with either β-thalassemia or HbE trait and in African Americans with sickle cell anemia. Taken together, the data suggest that the functional motifs responsible for modulating F-cells and HbF levels reside within a 3 kb region in the second intron of BCL11A.

Nucleotide sequences of the D-loop region of human mitochondrial DNA from six small ethnic groups of Thailand i.e., Hill tribes (Lisu and Mussur), Phuthai, Lao Song, Chong, and aboriginal Sakai, were analyzed. The sequences were compared with those of native Thai populations from two provinces, Chiang Mai and Khon Kaen. Based on a comparison of the 563-bp sequences in 215 Thai individuals, 137 different sequence types were observed. Of these, 124 were unique to their respective populations, whereas 13 were shared between two to five populations. The intergenic COII/tRNA Lys 9-bp deletion was observed in every Thai population examined, except for the Sakai, with varying frequencies ranging from 18% to 40%. The D-loop sequences variation, and phylogenetic analysis, suggested that the 9-bp deletion had occurred in a very ancient ancestry of Southeast Asians, although multiple origins of the deletion cannot be ruled out. Genetic distances, based on net nucleotide diversities, between populations revealed that the Sakai were distantly related to the other Thai populations, while the Lao Song and Chong were closely related to each other. Close genetic affinities were also observed among the Hill tribes, Phuthai, and native northeast Thai (Khon Kaen), indicating that they may share some degree of the common ancestral maternal lineages.

Implementation of a prevention and control program accompanying with a referral system for prenatal diagnosis is technically feasible in northeast Thailand and a large number of severe thalassemia diseases have been prevented during the past 16 years of operation.

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DNA variation on the non-recombining portion of the Y chromosome was examined in 610 male samples from 14 global populations in north, east, and southeast Asia, and other regions of the world. Eight haplotypes were observed by analyses of seven biallelic polymorphic markers ( DYS257(108), DYS287, SRY(4064), SRY(10831), RPS4Y(711), M9, and M15) and were unevenly distributed among the populations. Maximum parsimony tree for the eight haplotypes showed that these haplotypes could be classified into four distinct lineages characterized by three key mutations: an insertion of the Y Alu polymorphic (YAP) element at DYS287, a C-to-G transversion at M9, and a C-to-T transition at RPS4Y(711). Of the four lineages, three major lineages (defined by the allele of YAP(+), M9-G, and RPS4Y-T, respectively) accounted for 98.6% of the Asian populations studied, indicating that these three paternal lineages have contributed to the formation of modern Asian populations. Moreover, phylogenetic analysis revealed three monophyletic Asian clusters, which consisted of north Asian, Japanese, and Han Chinese/southeast Asian populations, respectively. Coalescence analysis in the haplotype tree showed that the estimated ages for three key mutations ranged from 53,000 to 95,000 years, suggesting that the three lineages were separated from one another during early stages of human evolutionary history. The distribution patterns of the Y-haplotypes and mutational ages for the key markers suggest that three major groups with different paternal ancestries separately migrated to prehistoric east and southeast Asia.