Norton Heather L, Edwards Melissa, Krithika S, Johnson Monique, Werren Elizabeth A, Parra Esteban J
Department of Anthropology, University of Cincinnati, Cincinnati, OH, 45238.
Department of Anthropology, University of Toronto Mississauga, Toronto, ON, Canada.
Am J Phys Anthropol. 2016 Aug;160(4):570-81. doi: 10.1002/ajpa.22861. Epub 2015 Sep 10.
The main goals of this study are to 1) quantitatively measure skin, hair, and iris pigmentation in a diverse sample of individuals, 2) describe variation within and between these samples, and 3) demonstrate how quantitative measures can facilitate genotype-phenotype association tests.
We quantitatively characterize skin, hair, and iris pigmentation using the Melanin (M) Index (skin) and CIELab values (hair) in 1,450 individuals who self-identify as African American, East Asian, European, Hispanic, or South Asian. We also quantify iris pigmentation in a subset of these individuals using CIELab values from high-resolution iris photographs. We compare mean skin M index and hair and iris CIELab values among populations using ANOVA and MANOVA respectively and test for genotype-phenotype associations in the European sample.
All five populations are significantly different for skin (P <2 × 10(-16) ) and hair color (P <2 × 10(-16) ). Our quantitative analysis of iris and hair pigmentation reinforces the continuous, rather than discrete, nature of these traits. We confirm the association of three loci (rs16891982, rs12203592, and rs12913832) with skin pigmentation and four loci (rs12913832, rs12203592, rs12896399, and rs16891982) with hair pigmentation. Interestingly, the derived rs12203592 T allele located within the IRF4 gene is associated with lighter skin but darker hair color.
The quantitative methods used here provide a fine-scale assessment of pigmentation phenotype and facilitate genotype-phenotype associations, even with relatively small sample sizes. This represents an important expansion of current investigations into pigmentation phenotype and associated genetic variation by including non-European and admixed populations. Am J Phys Anthropol 160:570-581, 2016. © 2015 Wiley Periodicals, Inc.
本研究的主要目标是：1）对不同个体样本的皮肤、头发和虹膜色素沉着进行定量测量；2）描述这些样本内部和之间的差异；3）证明定量测量如何促进基因型-表型关联测试。
我们使用黑色素（M）指数（皮肤）和CIELab值（头发）对1450名自我认定为非裔美国人、东亚人、欧洲人、西班牙裔或南亚人的个体的皮肤、头发和虹膜色素沉着进行定量表征。我们还使用高分辨率虹膜照片中的CIELab值对这些个体的一个子集的虹膜色素沉着进行量化。我们分别使用方差分析（ANOVA）和多变量方差分析（MANOVA）比较各人群之间的平均皮肤M指数以及头发和虹膜的CIELab值，并在欧洲样本中测试基因型-表型关联。
所有五个群体在皮肤（P <2×10^(-16)）和头发颜色（P <2×10^(-16)）方面均存在显著差异。我们对虹膜和头发色素沉着的定量分析强化了这些性状的连续性而非离散性。我们证实了三个位点（rs16891982、rs12203592和rs12913832）与皮肤色素沉着相关，以及四个位点（rs12913832、rs12203592、rs12896399和rs16891982）与头发色素沉着相关。有趣的是，位于IRF4基因内的衍生rs12203592 T等位基因与较浅的皮肤但较深的头发颜色相关。
这里使用的定量方法提供了对色素沉着表型的精细评估，并促进了基因型-表型关联，即使样本量相对较小。通过纳入非欧洲和混合人群，这代表了当前对色素沉着表型和相关遗传变异研究的重要扩展。《美国体质人类学杂志》160:570 - 581，2016年。©2015威利期刊公司。
