title: Implications of the admixture process in skin color molecular assessment.
abstract: The understanding of the complex genotype-phenotype architecture of human pigmentation has clear implications for the evolutionary history of humans, as well as for medical and forensic practices. Although dozens of genes have previously been associated with human skin color, knowledge about this trait remains incomplete. In particular, studies focusing on populations outside the European-North American axis are rare, and, until now, admixed populations have seldom been considered. The present study was designed to help fill this gap. Our objective was to evaluate possible associations of 18 single nucleotide polymorphisms (SNPs), located within nine genes, and one pseudogene with the Melanin Index (MI) in two admixed Brazilian populations (Gaucho, N = 352; Baiano, N = 148) with different histories of geographic and ethnic colonization. Of the total sample, four markers were found to be significantly associated with skin color, but only two (SLC24A5 rs1426654, and SLC45A2 rs16891982) were consistently associated with MI in both samples (Gaucho and Baiano). Therefore, only these 2 SNPs should be preliminarily considered to have forensic significance because they consistently showed the association independently of the admixture level of the populations studied. We do not discard that the other two markers (HERC2 rs1129038 and TYR rs1126809) might be also relevant to admixed samples, but additional studies are necessary to confirm the real importance of these markers for skin pigmentation. Finally, our study shows associations of some SNPs with MI in a modern Brazilian admixed sample, with possible applications in forensic genetics. Some classical genetic markers in Euro-North American populations are not associated with MI in our sample. Our results point out the relevance of considering population differences in selecting an appropriate set of SNPs as phenotype predictors in forensic practice.
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Caio Cesar Silva de
authors.initials: CC
authors.lastname: Cerqueira
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Tábita
authors.initials: T
authors.lastname: Hünemeier
authors.affiliation: Laboratorio de Antropología Física, Departamento de Anatomía, Facultad de Medicina, Universidad Nacional Autónoma de Mexico, Mexico City, Mexico.
authors.forename: Jorge
authors.initials: J
authors.lastname: Gomez-Valdés
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Virgínia
authors.initials: V
authors.lastname: Ramallo
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Carla Daiana
authors.initials: CD
authors.lastname: Volasko-Krause
authors.affiliation: Departamento de Ciências Biológicas, Universidade Estadual do Sudoeste da Bahia, Jequié, Brazil.
authors.forename: Ana Angélica Leal
authors.initials: AA
authors.lastname: Barbosa
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Pedro
authors.initials: P
authors.lastname: Vargas-Pinilla
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Rodrigo Ciconet
authors.initials: RC
authors.lastname: Dornelles
authors.affiliation: Instituto Federal de Educação, Ciência e Tecnologia Farroupilha, Alegrete, Brazil.
authors.forename: Danaê
authors.initials: D
authors.lastname: Longo
authors.affiliation: Instituto de Alta Investigación, Universidad de Tarapacá, Facultad de Medicina, Universidad de Chile and Centro de Investigaciones del Hombre en el Desierto, Arica, Chile.
authors.forename: Francisco
authors.initials: F
authors.lastname: Rothhammer
authors.affiliation: Universidad de Antioquia, Medellín, Colombia.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bedoya
authors.affiliation: Unidad de Genómica de Poblaciones Aplicada a la Salud, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico; Instituto Nacional de Medicina Genómica, Mexico City, Mexico.
authors.forename: Samuel
authors.initials: S
authors.lastname: Canizales-Quinteros
authors.affiliation: Molecular Genetics Laboratory, Escuela Nacional de Antropología e Historia, Mexico City, Mexico.
authors.forename: Victor
authors.initials: V
authors.lastname: Acuña-Alonzo
authors.affiliation: Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
authors.forename: Carla
authors.initials: C
authors.lastname: Gallo
authors.affiliation: Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Perú
authors.forename: Giovanni
authors.initials: G
authors.lastname: Poletti
authors.affiliation: Centro Nacional Patagónico, CONICET, Puerto Madryn, Argentina.
authors.forename: Rolando
authors.initials: R
authors.lastname: González-José
authors.affiliation: Departamento de Estatística, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Francisco Mauro
authors.initials: FM
authors.lastname: Salzano
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Departamento de Estatística, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Sídia Maria
authors.initials: SM
authors.lastname: Callegari-Jacques
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; INAGEMP - Instituto Nacional de Genética Médica Populacional, Porto Alegre, Brazil.
authors.forename: Lavínia
authors.initials: L
authors.lastname: Schuler-Faccini
authors.affiliation: Department of Genetics, Evolution and Environment and UCL Genetics Institute, University College London, London, United Kingdom.
authors.forename: Andrés
authors.initials: A
authors.lastname: Ruiz-Linares
authors.affiliation: Departamento de Genética, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Maria
authors.initials: M
authors.lastname: Cátira Bortolini
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001947:Breeding; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D008297:Male; D008543:Melanins / Q000378:metabolism; D008875:Middle Aged; D012880:Skin Pigmentation / Q000235:genetics*; D055815:Young Adult
chemical_list: D008543:Melanins