This study examined whether the prediction of pigmentary phenotype from DNA is possible across populations of diverse origin.
Pigmentation of the skin, hair, and eyes has shown remarkable levels of variation across human populations. Identifying the genetic loci that underlie this variation has potential applications in forensic science, since this would facilitate the determination of the probability of certain phenotypic characteristics (for example, skin, hair, and eye color), which would help in identifying potential suspects or unidentified victims. To date, however, most of the research in this field has identified genetic loci responsible for variation in hair and iris pigmentation in populations of European ancestry. Little is known about phenotypic variation and associated genetic loci in non-European and admixed populations. The current study addressed this issue by characterizing phenotypic and genetic variation in a diverse set of populations and by identifying associations between genotypes and quantitatively measured pigmentary phenotype. Pigmentation measurements and DNA were collected from individuals living in Cincinnati (Ohio) who self-identified as African-American or Hispanic. This sample was supplemented from the same testing of two previously collected admixed samples from outside the United States (Mexico and Brazil), as well as a previously collected sample of individuals who self-identified as being European, East-Asian, or South- Asian ancestry from Toronto (Canada). Skin, hair, and Iris phenotype were assessed using quantitative methods. Results indicate that although significant differences exist in skin pigmentation phenotype between the population samples, there was significant variation within these samples, particularly in admixed populations. Overall, the findings indicate that the prediction of pigmentary traits from genetic data in non-European or admixed populations poses a significant challenge. 10 figures, 7 tables, and 51 references
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Date Published: February 1, 2019