title: The effect of genetic admixture in an association study: genetic polymorphisms and chromosome aberrations in a Colombian population exposed to organic solvents.
abstract: The human population is heterogeneous in genetic susceptibility, chromosomal instability and disease risk; all factors which depend on inherited genetic constitution and acquired nongenetic environmental and occupational factors. Recently, special attention has been directed to the identification of sources of potential bias in population studies of gene-environment interactions including genetic admixture. The aim of this study was to evaluate the effect of genetic admixture in the association of genetic polymorphisms and chromosome aberrations (CA) in a population exposed to organic solvents. We assessed genetic admixture via 34 genetic ancestry informative markers (AIMs) in 398 Colombian individuals. We report a statistically significant difference of higher CA frequency in individuals' below-average European component, and in individuals' above-average Native American component after adjusting for covariates. In addition, the confounding risk ratio values are ≥10% than the adjusted risk ratio, suggesting that population stratification is a confounding factor in this gene-environment association study. Furthermore, after adjusting for individual admixture proportions and covariates, the results demonstrate that glutathione-S-transferase M1 (GSTM1)-null is associated with CA frequency increase. These results suggest that gene-environment association studies that involve recently admixed populations should take into consideration population stratification as a confounding factor and suggest GSTM1-null as a genetic marker associated with CA frequency increase.
authors.affiliation: Department of Biology, Research Group Genetic Toxicology and Cytogenetics, Faculty of Natural Sciences and Education, Universidad del Cauca, Popayán, Cauca, Colombia.
authors.forename: Luz Stella
authors.initials: LS
authors.lastname: Hoyos-Giraldo
authors.forename: Luisa F
authors.initials: LF
authors.lastname: Escobar-Hoyos
authors.forename: Ingrid
authors.initials: I
authors.lastname: Reyes-Carvajal
authors.forename: Jharley J
authors.initials: JJ
authors.lastname: García
authors.forename: Liliana
authors.initials: L
authors.lastname: Córdoba
authors.forename: Adalberto Sánchez
authors.initials: AS
authors.lastname: Gómez
authors.forename: Felipe
authors.initials: F
authors.lastname: García-Vallejo
authors.forename: Nohelia
authors.initials: N
authors.lastname: Cajas-Salazar
authors.forename: Silvio
authors.initials: S
authors.lastname: Carvajal
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bedoya
mesh_terms: D002869:Chromosome Aberrations / Q000139:chemically induced*; D003105:Colombia / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005787:Gene Frequency; D059647:Gene-Environment Interaction; D056726:Genetic Association Studies; D005819:Genetic Markers; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D008297:Male; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology; D016273:Occupational Exposure / Q000009:adverse effects*; D009930:Organic Chemicals / Q000009:adverse effects*; D011110:Polymorphism, Genetic / Q000187:drug effects*; D011159:Population Surveillance; D012997:Solvents / Q000009:adverse effects*
chemical_list: D005819:Genetic Markers; D009930:Organic Chemicals; D012997:Solvents
keywords: Chromosome aberrations; ancestry informative markers; genetic admixture; genetic polymorphisms; organic solvents exposure; population stratification