Abstract：
BACKGROUND: Forensic DNA phenotyping (FDP) consists of the use of methodologies for predicting externally visible characteristics (EVCs) from the genetic material of biological samples found in crime scenes and has proven to be a promising tool in aiding human identification in police activities. Currently, methods based on multiplex assays and statistical models of prediction of EVCs related to hair, skin, and iris pigmentation using panels of SNP and INDEL biomarkers have already been developed and validated by the forensic scientific community. As well as traces of pigmentation, an individual\'s perceived age (PA) can also be considered an EVC and its estimation in unknown individuals can be useful for the progress of investigations. Liu and colleagues (2016) were pioneers in evidencing that, in addition to lifestyle and environmental factors, the presence of SNP and INDEL variants in the MC1R gene - which encodes a transmembrane receptor responsible for regulating melanin production - seems to contribute to an individual\'s PA. The group highlighted the association between these MC1R gene polymorphisms and the PA in the European population, where carriers of risk haplotypes appeared to be up to 2 years older in comparison to their chronological age (CA).
OBJECTIVE: Understanding that genotype-phenotype relationships cannot be extrapolated between different population groups, this study aimed to test this hypothesis and verify the applicability of this variant panel in the Rio Grande do Sul admixed population.
METHODS: Based on genomic data from a sample of 261 volunteers representative of gaucho population and using a multiple linear regression (MLR) model, our group was able to verify a significant association among nine intronic variants in loci adjacent to MC1R (e.g., AFG3L1P, TUBB3, FANCA) and facial age appearance, whose PA was defined after age heteroclassification of standard frontal face images through 11 assessors.
RESULTS: Different from that observed in European populations, our results show that the presence of effect alleles (R) of the selected variants in our sample influenced both younger and older face phenotypes. The influence of each variant on PA is expressed as β values.
CONCLUSIONS: There are important molecular mechanisms behind the effects of MC1R locus on PA, and the genomic background of each population seems to be crucial to determine this influence.
OBJECTIVE: Understanding that genotype-phenotype relationships cannot be extrapolated between different population groups, this study aimed to test this hypothesis and verify the applicability of this variant panel in the Rio Grande do Sul admixed population.
METHODS: Based on genomic data from a sample of 261 volunteers representative of gaucho population and using a multiple linear regression (MLR) model, our group was able to verify a significant association among nine intronic variants in loci adjacent to MC1R (e.g., AFG3L1P, TUBB3, FANCA) and facial age appearance, whose PA was defined after age heteroclassification of standard frontal face images through 11 assessors.
RESULTS: Different from that observed in European populations, our results show that the presence of effect alleles (R) of the selected variants in our sample influenced both younger and older face phenotypes. The influence of each variant on PA is expressed as β values.
CONCLUSIONS: There are important molecular mechanisms behind the effects of MC1R locus on PA, and the genomic background of each population seems to be crucial to determine this influence.
摘要：
背景：法医DNA表型（FDP）包括使用方法从犯罪现场发现的生物样品的遗传物质中预测外部可见特征（EVC），并已被证明是一种有前途的工具在警察活动中帮助人类识别。目前,基于多重分析和统计模型的方法预测与头发相关的EVC，皮肤,使用SNP和INDEL生物标志物组的虹膜色素沉着已经被法医科学界开发和验证。除了色素沉着的痕迹，个体的感知年龄(PA)也可以被认为是EVC,其在未知个体中的估计对于调查的进展可能是有用的.刘及其同事(2016)是证明，除了生活方式和环境因素，MC1R基因中SNP和INDEL变体的存在-编码负责调节黑色素产生的跨膜受体-似乎与个体的PA有关.该小组强调了这些MC1R基因多态性与欧洲人群中的PA之间的关联，与实际年龄（CA）相比，风险单倍型携带者似乎要大2岁。
目的：了解基因型-表型关系不能在不同人群之间外推，这项研究旨在检验这一假设，并验证该变体面板在南里奥格兰德混合人群中的适用性。
方法：基于来自261名代表gaucho人群的志愿者样本的基因组数据，并使用多元线性回归（MLR）模型，我们小组能够验证与MC1R相邻基因座中9个内含子变体之间的显著关联(例如，AFG3L1P,TUBB3，FANCA）和面部年龄外观，其PA是在通过11名评估人员对标准正面面部图像进行年龄异分类后定义的。
结果：与在欧洲人群中观察到的不同，我们的结果表明,我们样本中所选择的变异体的效应等位基因(R)的存在影响了较年轻和较年长的面部表型.每种变体对PA的影响表示为β值。
结论：MC1R基因座对PA的影响背后有重要的分子机制，每个群体的基因组背景似乎对决定这种影响至关重要。
目的：了解基因型-表型关系不能在不同人群之间外推，这项研究旨在检验这一假设，并验证该变体面板在南里奥格兰德混合人群中的适用性。
方法：基于来自261名代表gaucho人群的志愿者样本的基因组数据，并使用多元线性回归（MLR）模型，我们小组能够验证与MC1R相邻基因座中9个内含子变体之间的显著关联(例如，AFG3L1P,TUBB3，FANCA）和面部年龄外观，其PA是在通过11名评估人员对标准正面面部图像进行年龄异分类后定义的。
结果：与在欧洲人群中观察到的不同，我们的结果表明,我们样本中所选择的变异体的效应等位基因(R)的存在影响了较年轻和较年长的面部表型.每种变体对PA的影响表示为β值。
结论：MC1R基因座对PA的影响背后有重要的分子机制，每个群体的基因组背景似乎对决定这种影响至关重要。
