title: Genetic Ancestry and Susceptibility to Late-Onset Alzheimer Disease (LOAD) in the Admixed Colombian Population.
abstract: BACKGROUND
  Differences in the prevalence of dementia among populations and in the effect of apolipoprotein E (APOE) on the emergence of Alzheimer disease (AD), which is the main type of dementia, have been reported.
  
  
  METHODS
  This study estimated the ancestry of a group of individuals with late-onset Alzheimer disease (LOAD) (N=280) and established whether there were any differences when compared with a control group (N=357) in a sample of the Colombian population.
  
  
  RESULTS
  When the analyses were adjusted for known risk factors such as age, sex, presence of APOE[Latin Small Letter Open E]4, socioeconomic status, educational attainment, and place of birth, African ancestry was associated with an increased LOAD risk (odds ratio: 1.55; 95% confidence interval, 1.09-2.03; P=0.029), whereas Native American ancestry was associated with lower risk (odds ratio: 0.75; 95% confidence interval, 0.61-0.98; P=0.046), for every 10% increase in ancestry. In addition, there were significant differences in the proportion of Native American ancestry between carriers and noncarriers of the APOE[Latin Small Letter Open E]4 allele (Mann-Whitney U test, P=0.047), with noncarriers having higher mean Native American ancestry when compared with carriers.
  
  
  CONCLUSIONS
  Our results are consistent with the presence of variants of African origin in the genome of the Colombian population and different from APOE[Latin Small Letter Open E]4 that represents a risk factor for the development of LOAD, whereas variants of Native American origin may be conferring protection. However, unknown environmental factors or epigenetic differences among continental groups could also explain the observed associations.
authors.affiliation: *Molecular Genetics Group ‡Neuroscience Group, University of Antioquia, Medellín †Neuropsychology Group, Surcolombiana University §Genomic Medicine Group, Surcolombiana University, Neiva, Colombia ∥Department of Clinical Psychology and Psychobiology and Institute of Neuroscience, Barcelona University ¶Research Institute Sant Joan de Déu (IR-SJD), Barcelona, Spain.
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Moreno
authors.forename: Sebastián
authors.initials: S
authors.lastname: Pino
authors.forename: Ángela
authors.initials: Á
authors.lastname: Ríos
authors.forename: Francisco
authors.initials: F
authors.lastname: Lopera
authors.forename: Henry
authors.initials: H
authors.lastname: Ostos
authors.forename: Marc
authors.initials: M
authors.lastname: Via
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bedoya
mesh_terms: D001741:Black or African American / Q000235:genetics*; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D003105:Colombia / Q000453:epidemiology; D005260:Female; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006801:Humans; D007198:Indians, North American / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D044465:White People / Q000235:genetics