title: African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia.
abstract: African descended populations exhibit an increased prevalence of asthma and allergies compared to Europeans. One approach to distinguish between environmental and genetic explanations for this difference is to study relationships of asthma risk to individual admixture. We aimed to determine the admixture proportions of a case-control sample from the Caribbean Coast of Colombia currently participating in genetic studies for asthma, and to test for population stratification and association between African ancestry and asthma and total serum IgE levels (tIgE). We genotyped 368 asthmatics and 365 non-asthmatics for 52 autosomal ancestry informative markers, six mtDNA haplogroups and nine haplogroups and five microsatellites in Y chromosome. Autosomal admixture proportions, population stratification, and associations between ancestry and the phenotypes were estimated by ADMIXMAP. The average admixture proportions among asthmatics were 42.8% European, 39.9% African and 17.2% Native American and among non-asthmatics they were 44.2% (P = 0.068), 37.6% (P = 0.007) and 18.1% (P = 0.050), respectively. In the total sample, the paternal contributions were 71% European, 25% African and 4.0% Native American and the maternal lineages were 56.8% Native American, and 20.2% African; 22.9% of the individuals carried other non-Native American mtDNA haplogroups. African ancestry was significantly associated with asthma (OR: 2.97; 95% CI: 1.08-8.08), high tIgE (OR: 1.9; 95% CI: 1.17-3.12) and socioeconomic status (OR = 0.64; 95% CI: 0.47-0.87). Significant population stratification was observed in this sample. Our findings indicate that genetic factors can explain the association between asthma and African ancestry and suggest that this sample is a useful resource for performing admixture mapping for asthma.
authors.affiliation: Institute for Immunological Research, University of Cartagena, Bolívar, Colombia.
authors.forename: Candelaria
authors.initials: C
authors.lastname: Vergara
authors.forename: Luis
authors.initials: L
authors.lastname: Caraballo
authors.forename: Dilia
authors.initials: D
authors.lastname: Mercado
authors.forename: Silvia
authors.initials: S
authors.lastname: Jimenez
authors.forename: Winston
authors.initials: W
authors.lastname: Rojas
authors.forename: Nicholas
authors.initials: N
authors.lastname: Rafaels
authors.forename: Tracey
authors.initials: T
authors.lastname: Hand
authors.forename: Monica
authors.initials: M
authors.lastname: Campbell
authors.forename: Yuhjung J
authors.initials: YJ
authors.lastname: Tsai
authors.forename: Li
authors.initials: L
authors.lastname: Gao
authors.forename: Constanza
authors.initials: C
authors.lastname: Duque
authors.forename: Sergio
authors.initials: S
authors.lastname: Lopez
authors.forename: Gabriel
authors.initials: G
authors.lastname: Bedoya
authors.forename: Andrés
authors.initials: A
authors.lastname: Ruiz-Linares
authors.forename: Kathleen C
authors.initials: KC
authors.lastname: Barnes
mesh_terms: D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000235:genetics*; D044383:Black People / Q000235:genetics*; D016022:Case-Control Studies; D041322:Chromosomes, Human, Y / Q000235:genetics; D003105:Colombia / Q000453:epidemiology; D004272:DNA, Mitochondrial / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005819:Genetic Markers; D020022:Genetic Predisposition to Disease; D005828:Genetics, Population; D005838:Genotype; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood* / Q000235:genetics; D007198:Indians, North American / Q000235:genetics; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D012307:Risk Factors; D017422:Sequence Analysis, DNA; D012923:Social Class; D044465:White People / Q000235:genetics; D055815:Young Adult
chemical_list: D004272:DNA, Mitochondrial; D005819:Genetic Markers; D007073:Immunoglobulin E