title: Differentiation of African components of ancestry to stratify groups in a case-control study of a Brazilian urban population.
abstract: BACKGROUND
  Balancing the subject composition of case and control groups to create homogenous ancestries between each group is essential for medical association studies.
  
  
  METHODS
  We explored the applicability of single-tube 34-plex ancestry informative markers (AIM) single nucleotide polymorphisms (SNPs) to estimate the African Component of Ancestry (ACA) to design a future case-control association study of a Brazilian urban sample.
  
  
  RESULTS
  One hundred eighty individuals (107 case group; 73 control group) self-described as white, brown-intermediate or black were selected. The proportions of the relative contribution of a variable number of ancestral population components were similar between case and control groups. Moreover, the case and control groups demonstrated similar distributions for ACA <0.25 and >0.50 categories. Notably a high number of outlier values (23 samples) were observed among individuals with ACA <0.25. These individuals presented a high probability of Native American and East Asian ancestral components; however, no individuals originally giving these self-described ancestries were observed in this study.
  
  
  CONCLUSIONS
  The strategy proposed for the assessment of ancestry and adjustment of case and control groups for an association study is an important step for the proper construction of the study, particularly when subjects are taken from a complex urban population. This can be achieved using a straight forward multiplexed AIM-SNPs assay of highly discriminatory ancestry markers.
authors.affiliation: Faculty of Pharmaceutical Sciences, University of Sao Paulo, São Paulo, Brazil. viviansilbiger@usp.br
authors.forename: Vivian N
authors.initials: VN
authors.lastname: Silbiger
authors.forename: Mario H
authors.initials: MH
authors.lastname: Hirata
authors.forename: Andre D
authors.initials: AD
authors.lastname: Luchessi
authors.forename: Fabiana D V
authors.initials: FD
authors.lastname: Genvigir
authors.forename: Alvaro
authors.initials: A
authors.lastname: Cerda
authors.forename: Alice C
authors.initials: AC
authors.lastname: Rodrigues
authors.forename: Maria A V
authors.initials: MA
authors.lastname: Willrich
authors.forename: Simone S
authors.initials: SS
authors.lastname: Arazi
authors.forename: Egidio L
authors.initials: EL
authors.lastname: Dorea
authors.forename: Marcia M S
authors.initials: MM
authors.lastname: Bernik
authors.forename: Andre A
authors.initials: AA
authors.lastname: Faludi
authors.forename: Marcelo C
authors.initials: MC
authors.lastname: Bertolami
authors.forename: Carla
authors.initials: C
authors.lastname: Santos
authors.forename: Angel
authors.initials: A
authors.lastname: Carracedo
authors.forename: Antonio
authors.initials: A
authors.lastname: Salas
authors.forename: Ana
authors.initials: A
authors.lastname: Freire
authors.forename: Maria Victoria
authors.initials: MV
authors.lastname: Lareu
authors.forename: Christopher
authors.initials: C
authors.lastname: Phillips
authors.forename: Liliana
authors.initials: L
authors.lastname: Porras-Hurtado
authors.forename: Manuel
authors.initials: M
authors.lastname: Fondevila
authors.forename: Rosario D C
authors.initials: RD
authors.lastname: Hirata
mesh_terms: D044466:Asian People / Q000208:ethnology / Q000235:genetics; D044383:Black People / Q000208:ethnology / Q000235:genetics*; D001938:Brazil / Q000208:ethnology; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006937:Hypercholesterolemia / Q000235:genetics*; D007199:Indians, South American / Q000208:ethnology* / Q000235:genetics; D008297:Male; D020641:Polymorphism, Single Nucleotide; D044382:Population Groups / Q000208:ethnology / Q000235:genetics; D014505:Urban Population; D044465:White People / Q000208:ethnology / Q000235:genetics