Previous genetic studies on hair morphology focused on the overall morphology of the hair using data collected by self-report or researcher observation. Here, we present the first genome-wide association study (GWAS) of a micro-level quantitative measure of hair curvature. We compare these results to GWAS results obtained using a macro-level classification of observable hair curvature performed in the same sample of twins and siblings of European descent. Observational data were collected by trained observers, while quantitative data were acquired using an Optical Fibre Diameter Analyser (OFDA). The GWAS for both the observational and quantitative measures of hair curvature resulted in genome-wide significant signals at chromosome 1q21.3 close to the trichohyalin (TCHH) gene, previously shown to harbor variants associated with straight hair morphology in Europeans. All genetic variants reaching genome-wide significance for both GWAS (quantitative measure lead single-nucleotide polymorphism [SNP] rs12130862, p = 9.5 × 10–09; observational measure lead SNP rs11803731, p = 2.1 × 10–17) were in moderate to very high linkage disequilibrium (LD) with each other (minimum r2 = .45), indicating they represent the same genetic locus. Conditional analyses confirmed the presence of only one signal associated with each measure at this locus. Results from the quantitative measures reconfirmed the accuracy of observational measures.

中文翻译：

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全基因组关联扫描对人类头发曲率的定量和观察测量的比较

先前关于头发形态的遗传研究主要使用通过自我报告或研究人员观察收集的数据来研究头发的整体形态。在这里，我们提出了第一个对头发曲率进行微观定量测量的全基因组关联研究 (GWAS)。我们将这些结果与在欧洲血统的双胞胎和兄弟姐妹的同一样本中使用可观察头发曲率的宏观分类获得的 GWAS 结果进行比较。观察数据由训练有素的观察者收集，而定量数据则使用光纤直径分析仪 (OFDA) 获得。用于头发曲率的观察和定量测量的 GWAS 在靠近毛透明蛋白的 1q21.3 号染色体上产生了全基因组显着信号。TCHH) 基因，以前显示在欧洲人中含有与直发形态相关的变异。所有遗传变异均达到 GWAS 的全基因组意义（定量测量导致单核苷酸多态性 [SNP] rs12130862，p= 9.5 × 10–09; 观察性测量先导 SNP rs11803731，p= 2.1 × 10–17) 彼此处于中等到非常高的连锁不平衡 (LD) 中（最小r2= .45)，表明它们代表相同的基因位点。条件分析证实在该基因座处仅存在与每个测量相关的一个信号。定量测量的结果再次证实了观察测量的准确性。