Ancient origin of the null allele se428 of the human ABO-Secretor locus (FUT2)
Ancient origin of the null allele se428 of the human ABO-Secretor locus (FUT2)
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DOI：
10.1007/s002399910028
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发表时间：
2000-03-01
影响因子：
3.9
通讯作者：
Kimura, H
中科院分区：
文献类型：
--
作者：
Koda, Y;Tachida, H;Kimura, H
在人类群体中，一个与野生型等位基因有几个核苷酸差异的空等位基因在编码α(1,2)聚焦转移酶的FUT2位点（abo -分泌位点）分离。为了估计这两个等位基因最近的共同祖先（MRCA）的年龄，我们对来自黑猩猩、大猩猩、猩猩和绿猴的FUT2同源物进行了测序。由于我们在这些物种中没有检测到该位点的替代率加速或任何异质性，假设人类和黑猩猩的分化时间为5千万年，估计MRCA的年龄约为3千万年。我们开发了一个简单的测试来检查FUT2的MRCA的年龄是否与从随机交配群体中取样的两个不同的中性等位基因的预期年龄一致。对FUT2数据的测试应用表明，MRCA的年龄太老，无法用简单的中性假设来解释，尽管我们的测试依赖于以人类种群规模的两倍为单位对人类和黑猩猩分化时间的准确估计。讨论了包括平衡选择在内的各种可能性，以解释MRCA的年龄。
Tn human populations, a null allele having several nucleotide differences from the wild-type allele is segregating at the FUT2 locus (the ABO-Secretor locus) encoding alpha(1,2)fucosyltransferase. To estimate the age of the most recent common ancestor (MRCA) of these two alleles, we sequenced FUT2 homologues from chimpanzee, gorilla, orangutan, and green monkey. Since we did not detect acceleration or any heterogeneity in the substitution rate at this locus among these species, the age of the MRCA was estimated to be around 3 MYA, assuming the divergence time of human and chimpanzee to be 5 MYA. We developed a simple test to examine whether or not the old age of the MRCA of the FUT2 is consistent with that expected for two divergent neutral alleles sampled from a random mating population. An application of the test to the data at FUT2 indicated that the age of the MRCA is too old to be explained by the simple neutral assumptions, although our test depends on accurate estimation of the divergence time of human and chimpanzee in units of twice the human population size. Various possibilities including balancing selection are discussed to explain this old age of the MRCA.