Itou Masaya, Sato Mitsuharu, Kitano Takashi
Department of Biomolecular Functional Engineering, College of Engineering, Ibaraki University, 4-12-1 Nakanarusawa-cho, Hitachi 316-8511, Japan.
Int J Evol Biol. 2013;2013:406209. doi: 10.1155/2013/406209. Epub 2013 Oct 29.
The human ABO blood group gene consists of three main alleles (A, B, and O) that encode a glycosyltransferase. The A and B alleles differ by two critical amino acids in exon 7, and the major O allele has a single nucleotide deletion (Δ261) in exon 6. Previous evolutionary studies have revealed that the A allele is the most ancient, B allele diverged from the A allele with two critical amino acid substitutions in exon 7, and the major O allele diverged from the A allele with Δ261 in exon 6. However, a recent phylogenetic network analysis study showed that the A allele of humans emerged through a recombination between the B and O alleles. In the previous study, a restricted dataset from only two populations was used. In this study, therefore, we used a large single nucleotide polymorphism (SNP) dataset from the HapMap Project. The results indicated that the A101-A201-O09 haplogroup was a recombinant lineage between the B and O haplotypes, containing the intact exon 6 from the B allele and the two critical A type sites in exon 7 from the major O allele. Its recombination point was assumed to be located just behind Δ261 in exon 6.
人类ABO血型基因由三个主要等位基因（A、B和O）组成，这些等位基因编码一种糖基转移酶。A等位基因和B等位基因在外显子7中有两个关键氨基酸不同，主要的O等位基因在外显子6中有一个单核苷酸缺失（Δ261）。先前的进化研究表明，A等位基因是最古老的，B等位基因通过外显子7中的两个关键氨基酸替换从A等位基因分化而来，主要的O等位基因通过外显子6中的Δ261从A等位基因分化而来。然而，最近一项系统发育网络分析研究表明，人类的A等位基因是通过B等位基因和O等位基因之间的重组产生的。在先前的研究中，仅使用了来自两个群体的有限数据集。因此，在本研究中，我们使用了来自HapMap计划的大型单核苷酸多态性（SNP）数据集。结果表明，A101 - A201 - O09单倍型组是B和O单倍型之间的重组谱系，包含来自B等位基因的完整外显子6和来自主要O等位基因外显子7中的两个关键A类型位点。其重组点假定位于外显子6中Δ261之后。
