title: Evidence of recent natural selection on the Southeast Asian deletion (--(SEA)) causing α-thalassemia in South China.
abstract: BACKGROUND
  The Southeast Asian deletion (--(SEA)) is the most commonly observed mutation among diverse α-thalassemia alleles in Southeast Asia and South China. It is generally argued that mutation --(SEA), like other variants causing hemoglobin disorders, is associated with protection against malaria that is endemic in these regions. However, little evidence has been provided to support this claim.
  
  
  RESULTS
  We first examined the genetic imprint of recent positive selection on the --(SEA) allele and flanking sequences in the human α-globin cluster, covering a genomic region spanning ~410 kb, by genotyping 28 SNPs in a Chinese population consisting of 76 --(SEA) heterozygotes and 138 normal individuals. The pattern of linkage disequilibrium (LD) and the long-range haplotype test revealed a signature of positive selection. The network of inferred haplotypes suggested a single origin of the --(SEA) allele.
  
  
  CONCLUSIONS
  Thus, our data support the hypothesis that the --(SEA) allele has been subjected to recent balancing selection, triggered by malaria.
authors.affiliation: Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, Guangdong, PR China.
authors.forename: Qin-Wei
authors.initials: QW
authors.lastname: Qiu
authors.forename: Dong-Dong
authors.initials: DD
authors.lastname: Wu
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Yu
authors.forename: Ti-Zhen
authors.initials: TZ
authors.lastname: Yan
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.forename: Zhe-Tao
authors.initials: ZT
authors.lastname: Li
authors.forename: Yan-Hui
authors.initials: YH
authors.lastname: Liu
authors.forename: Ya-Ping
authors.initials: YP
authors.lastname: Zhang
authors.forename: Xiang-Min
authors.initials: XM
authors.lastname: Xu
mesh_terms: D044466:Asian People / Q000235:genetics*; D002885:Chromosomes, Human, Pair 16; D017353:Gene Deletion; D006239:Haplotypes; D006454:Hemoglobins / Q000235:genetics*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008288:Malaria / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D011995:Recombination, Genetic; D012641:Selection, Genetic; D017085:alpha-Thalassemia / Q000235:genetics*
chemical_list: D006454:Hemoglobins