Zago M A, Melo Santos E J, Clegg J B, Guerreiro J F, Martinson J J, Norwich J, Figueiredo M S
Department of Clinical Medicine, School of Medicine, Ribeirão Preto, Brazil.
Hum Biol. 1995 Aug;67(4):535-46.
The haplotypes of the alpha-globin gene cluster were determined for 99 Indians from the Brazilian Amazon region who belong to 5 tribes: Wayampí, Wayana-Apalaí, Kayapó, Arára, and Yanomámi. Three predominant haplotypes were identified: Ia (present in 38.9% of chromosomes), IIIa (25.8%), and IIe (22.1%). The only alpha-globin gene rearrangement detected was alpha alpha alpha 3.7 I gene triplication associated with haplotype IIIa, found in high frequencies (5.6% and 10.6%) in two tribes and absent in the others. alpha-Globin gene deletions that cause alpha-thalassemia were not seen, supporting the argument that malaria was absent in these populations until recently. The heterogeneous distribution of alpha-globin gene haplotypes and rearrangements among the different tribes differs markedly from the homogeneous distribution of beta-globin gene cluster haplotypes and reflects the action of various genetic mechanisms (genetic drift, founder effect, consanguinity) on small isolated population groups with a complicated history of divergence-fusion events. The alpha-globin gene haplotype distribution has some similarities to distributions observed in Southeast Asian and Pacific Island populations, indicating that these populations have considerable genetic affinities. However, the absence of several features of the alpha-globin gene cluster that are consistently present among the Pacific Islanders suggests that the similarity of haplotypes between Brazilian Indians and people from Polynesia, Micronesia, and Melanesia is more likely to result of ancient common ancestry rather than the consequence of recent direct genetic contribution through immigration.
对来自巴西亚马逊地区、分属5个部落（瓦扬皮、瓦亚纳 - 阿帕莱、卡亚波、阿拉拉和亚诺马米）的99名印第安人，测定了α-珠蛋白基因簇的单倍型。鉴定出三种主要单倍型：Ia（存在于38.9%的染色体中）、IIIa（25.8%）和IIe（22.1%）。检测到的唯一α-珠蛋白基因重排是与单倍型IIIa相关的ααα 3.7 I基因三倍体，在两个部落中高频出现（5.6%和10.6%），在其他部落中未出现。未发现导致α地中海贫血的α-珠蛋白基因缺失，这支持了这些人群直到最近才没有疟疾的观点。不同部落间α-珠蛋白基因单倍型和重排的异质分布与β-珠蛋白基因簇单倍型的均匀分布明显不同，反映了各种遗传机制（遗传漂变、奠基者效应、近亲繁殖）对具有复杂分化 - 融合事件历史的小隔离人群组的作用。α-珠蛋白基因单倍型分布与在东南亚和太平洋岛屿人群中观察到的分布有一些相似之处，表明这些人群有相当的遗传亲缘关系。然而，太平洋岛民中始终存在的α-珠蛋白基因簇的几个特征在这些人群中未出现，这表明巴西印第安人与来自波利尼西亚、密克罗尼西亚和美拉尼西亚的人群之间单倍型的相似性更可能是古代共同祖先的结果，而不是近期通过移民直接遗传贡献的结果。
