title: Genomic ancestry, self-reported "color" and quantitative measures of skin pigmentation in Brazilian admixed siblings.
abstract: A current concern in genetic epidemiology studies in admixed populations is that population stratification can lead to spurious results. The Brazilian census classifies individuals according to self-reported "color", but several studies have demonstrated that stratifying according to "color" is not a useful strategy to control for population structure, due to the dissociation between self-reported "color" and genomic ancestry. We report the results of a study in a group of Brazilian siblings in which we measured skin pigmentation using a reflectometer, and estimated genomic ancestry using 21 Ancestry Informative Markers (AIMs). Self-reported "color", according to the Brazilian census, was also available for each participant. This made it possible to evaluate the relationship between self-reported "color" and skin pigmentation, self-reported "color" and genomic ancestry, and skin pigmentation and genomic ancestry. We observed that, although there were significant differences between the three "color" groups in genomic ancestry and skin pigmentation, there was considerable dispersion within each group and substantial overlap between groups. We also saw that there was no good agreement between the "color" categories reported by each member of the sibling pair: 30 out of 86 sibling pairs reported different "color", and in some cases, the sibling reporting the darker "color" category had lighter skin pigmentation. Socioeconomic status was significantly associated with self-reported "color" and genomic ancestry in this sample. This and other studies show that subjective classifications based on self-reported "color", such as the one that is used in the Brazilian census, are inadequate to describe the population structure present in recently admixed populations. Finally, we observed that one of the AIMs included in the panel (rs1426654), which is located in the known pigmentation gene SLC24A5, was strongly associated with skin pigmentation in this sample.
authors.affiliation: Programa de Pós-Graduação em Educação Física, Universidade Católica de Brasília, Brasília, Distrito Federal, Brazil.
authors.forename: Tailce K M
authors.initials: TK
authors.lastname: Leite
authors.forename: Rômulo M C
authors.initials: RM
authors.lastname: Fonseca
authors.forename: Nanci M
authors.initials: NM
authors.lastname: de França
authors.forename: Esteban J
authors.initials: EJ
authors.lastname: Parra
authors.forename: Rinaldo W
authors.initials: RW
authors.lastname: Pereira
mesh_terms: D000293:Adolescent; D044383:Black People / Q000235:genetics; D001938:Brazil; D015894:Genome, Human; D006801:Humans; D008543:Melanins / Q000378:metabolism; D035781:Siblings; D012880:Skin Pigmentation / Q000235:genetics*; D012923:Social Class; D044465:White People / Q000235:genetics
chemical_list: D008543:Melanins
references.citation: Diabetologia. 2011 Aug;54(8):2038-46
references.pmid: 21573907
references.citation: Hum Genet. 2005 Dec;118(3-4):424-33
references.pmid: 16208514
references.citation: PLoS One. 2011 Feb 16;6(2):e17063
references.pmid: 21359226
references.citation: Pharmacogenet Genomics. 2007 Sep;17(9):765-71
references.pmid: 17700365
references.citation: Exp Dermatol. 2009 Feb;18(2):175-7
references.pmid: 18637132
references.citation: Am J Hum Genet. 2003 Dec;73(6):1402-22
references.pmid: 14631557
references.citation: Int J Legal Med. 2007 Jan;121(1):36-9
references.pmid: 16847698
references.citation: Am J Hum Genet. 2007 Dec;81(6):1119-32
references.pmid: 17999355
references.citation: Am J Hum Biol. 2010 Mar-Apr;22(2):187-92
references.pmid: 19639555
references.citation: Am J Public Health. 2005 Dec;95(12):2191-7
references.pmid: 16257938
references.citation: Am J Hum Genet. 2000 Aug;67(2):444-61
references.pmid: 10873790
references.citation: Lancet. 1986 Feb 8;1(8476):307-10
references.pmid: 2868172
references.citation: Science. 2005 Dec 16;310(5755):1782-6
references.pmid: 16357253
references.citation: Am J Phys Anthropol. 2000 May;112(1):17-27
references.pmid: 10766940
references.citation: Am J Phys Anthropol. 2009 Apr;138(4):375-83
references.pmid: 18951390
references.citation: Am J Hum Genet. 2001 Jan;68(1):281-6
references.pmid: 11090340
references.citation: Diabetologia. 2009 Aug;52(8):1528-36
references.pmid: 19526211
references.citation: J Epidemiol. 2011;21(4):240-5
references.pmid: 21498954
references.citation: Nat Genet. 2004 Nov;36(11 Suppl):S54-60
references.pmid: 15508005
references.citation: Nucleic Acids Res. 1988 Feb 11;16(3):1215
references.pmid: 3344216
references.citation: Am J Hum Genet. 2003 Jun;72(6):1370-88
references.pmid: 12721957
references.citation: Hum Genet. 2003 Apr;112(4):387-99
references.pmid: 12579416
references.citation: Am J Hum Genet. 2003 Jun;72(6):1492-1504
references.pmid: 12817591
references.citation: J Biol Chem. 2008 Feb 29;283(9):5486-95
references.pmid: 18166528
references.citation: Am J Hum Genet. 1998 Jul;63(1):241-51
references.pmid: 9634509
references.citation: Breast Cancer Res Treat. 2010 Sep;123(2):525-30
references.pmid: 20140701
references.citation: Mol Biol Evol. 2006 Sep;23(9):1697-706
references.pmid: 16757656
references.citation: Proc Natl Acad Sci U S A. 2003 Jan 7;100(1):177-82
references.pmid: 12509516
references.citation: Fam Med. 2005 May;37(5):360-3
references.pmid: 15883903
references.citation: Curr Anthropol. 2009 Dec;50(6):787-819
references.pmid: 20614657
references.citation: Genetics. 2000 Jun;155(2):945-59
references.pmid: 10835412
references.citation: Hum Hered. 2006;62(4):190-5
references.pmid: 17106202
references.citation: Mol Biol Evol. 2007 Mar;24(3):710-22
references.pmid: 17182896
references.citation: Am J Hum Biol. 2003 Nov-Dec;15(6):824-34
references.pmid: 14595874
references.citation: Clin Genet. 2007 Apr;71(4):359-66
references.pmid: 17470138
references.citation: J Forensic Sci. 2010 Mar 1;55(2):315-22
references.pmid: 20158590
references.citation: Joint Bone Spine. 2012 May;79(3):256-61
references.pmid: 21724442
references.citation: Nat Rev Genet. 2004 Aug;5(8):611-8
references.pmid: 15266343