Beall C M, Brittenham G M, Strohl K P, Blangero J, Williams-Blangero S, Goldstein M C, Decker M J, Vargas E, Villena M, Soria R, Alarcon A M, Gonzales C
Case Western Reserve University, Cleveland, Ohio 44106-7125, USA.
Am J Phys Anthropol. 1998 Jul;106(3):385-400. doi: 10.1002/(SICI)1096-8644(199807)106:3<385::AID-AJPA10>3.0.CO;2-X.
Elevated hemoglobin concentrations have been reported for high-altitude sojourners and Andean high-altitude natives since early in the 20th century. Thus, reports that have appeared since the 1970s describing relatively low hemoglobin concentration among Tibetan high-altitude natives were unexpected. These suggested a hypothesis of population differences in hematological response to high-altitude hypoxia. A case of quantitatively different responses to one environmental stress would offer an opportunity to study the broad evolutionary question of the origin of adaptations. However, many factors may confound population comparisons. The present study was designed to test the null hypothesis of no difference in mean hemoglobin concentration of Tibetan and Aymara native residents at 3,800-4,065 meters by using healthy samples that were screened for iron deficiency, abnormal hemoglobins, and thalassemias, recruited and assessed using the same techniques. The hypothesis was rejected, because Tibetan males had a significantly lower mean hemoglobin concentration of 15.6 gm/dl compared with 19.2 gm/dl for Aymara males, and Tibetan females had a mean hemoglobin concentration of 14.2 gm/dl compared with 17.8 gm/dl for Aymara females. The Tibetan hemoglobin distribution closely resembled that from a comparable, sea-level sample from the United States, whereas the Aymara distribution was shifted toward 3-4 gm/dl higher values. Genetic factors accounted for a very high proportion of the phenotypic variance in hemoglobin concentration in both samples (0.86 in the Tibetan sample and 0.87 in the Aymara sample). The presence of significant genetic variance means that there is the potential for natural selection and genetic adaptation of hemoglobin concentration in Tibetan and Aymara high-altitude populations.
自20世纪初以来，就有报道称高海拔地区的旅居者和安第斯高海拔地区的原住民血红蛋白浓度升高。因此，20世纪70年代以来出现的报道称，藏族高海拔地区原住民的血红蛋白浓度相对较低，这是出乎意料的。这些报道提出了关于人群对高海拔低氧血症血液学反应存在差异的假说。一个针对一种环境压力存在定量不同反应的案例，将为研究适应起源这一广泛的进化问题提供机会。然而，许多因素可能会混淆人群间的比较。本研究旨在通过使用经过缺铁、异常血红蛋白和地中海贫血筛查的健康样本，采用相同的技术进行招募和评估，来检验在海拔3800 - 4065米的藏族和艾马拉族原住民居民中，平均血红蛋白浓度没有差异的零假设。该假设被拒绝，因为藏族男性的平均血红蛋白浓度显著低于艾马拉族男性，分别为15.6克/分升和19.2克/分升；藏族女性的平均血红蛋白浓度为14.2克/分升，而艾马拉族女性为17.8克/分升。藏族血红蛋白分布与来自美国类似海平面样本的分布非常相似，而艾马拉族的分布则向高3 - 4克/分升的值偏移。遗传因素在两个样本中血红蛋白浓度的表型变异中占非常高的比例（藏族样本中为0.86，艾马拉族样本中为0.87）。显著遗传变异的存在意味着藏族和艾马拉族高海拔人群的血红蛋白浓度有自然选择和遗传适应的潜力。
