African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia.
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.
Vergara
Candelaria
C
Institute for Immunological Research, University of Cartagena, Bolívar, Colombia.
Caraballo
Luis
L
Mercado
Dilia
D
Jimenez
Silvia
S
Rojas
Winston
W
Rafaels
Nicholas
N
Hand
Tracey
T
Campbell
Monica
M
Tsai
Yuhjung J
YJ
Gao
Li
L
Duque
Constanza
C
Lopez
Sergio
S
Bedoya
Gabriel
G
Ruiz-Linares
Andrés
A
Barnes
Kathleen C
KC
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
D004272:DNA, Mitochondrial; D005819:Genetic Markers; D007073:Immunoglobulin E