| 2004 |
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| Extended linkage disequilibrium surrounding the hemoglobin E variant due to malarial
selection. |
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| Ohashi, J., Naka, I., Patarapotikul, J., Hananantachai, H., Brittenham, G., Looareesuwan, S.,
Clark, A. G., and Tokunaga, K. |
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| Department of Human Genetics, The University of Tokyo, Tokyo, Japan juno-
tky@uminacjp |
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| Abstract: The hemoglobin E variant (HbE; ( beta )26Glu-->Lys) is concentrated in parts of
Southeast Asia where malaria is endemic, and HbE carrier status has been shown to confer some protection against Plasmodium falciparum malaria. To
examine the effect of natural selection on the pattern of linkage disequilibrium (LD) and to infer the evolutionary history of the HbE variant, we analyzed
biallelic markers surrounding the HbE variant in a Thai population. Pairwise LD analysis of HbE and 43 surrounding biallelic markers revealed LD of HbE
extending beyond 100 kb, whereas no LD was observed between non-HbE variants and the same markers. The inferred haplotype network suggests a
single origin of the HbE variant in the Thai population. Forward-in-time computer simulations under a variety of selection models indicate that the HbE
variant arose 1,240-4,440 years ago. These results support the conjecture that the HbE mutation occurred recently, and the allele frequency has
increased rapidly. Our study provides another clear demonstration that a high-resolution LD map across the human genome can detect recent variants
that have been subjected to positive selection |
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| Published in:Am.J.Hum.Genet. 74[6], 1198-1208. 2004. |
