Human Genetics

, Volume 125, Issue 5, pp 565–579

African ancestry is associated with risk of asthma and high total serum IgE in a population from the Caribbean Coast of Colombia

  • Candelaria Vergara
  • Luis Caraballo
  • Dilia Mercado
  • Silvia Jimenez
  • Winston Rojas
  • Nicholas Rafaels
  • Tracey Hand
  • Monica Campbell
  • Yuhjung J. Tsai
  • Li Gao
  • Constanza Duque
  • Sergio Lopez
  • Gabriel Bedoya
  • Andrés Ruiz-Linares
  • Kathleen C. Barnes
Original Investigation

DOI: 10.1007/s00439-009-0649-2

Cite this article as:
Vergara, C., Caraballo, L., Mercado, D. et al. Hum Genet (2009) 125: 565. doi:10.1007/s00439-009-0649-2

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.

Abbreviations

tIgE

Total serum IgE

AIM

Ancestry informative marker

OR

Odds ratio

IC

Interval confidence

Pct 2.5

Percentile 2.5

Pct 97.5

Percentile 97.5

δ

Delta (differences in allelic frequencies between populations)

GCU

Government Community Units

HWE

Hardy–Weinberg equilibrium

ELISA

Enzyme linked immunosorbent assay

PCR/RFLP

Polymerase chain reaction/restriction fragment length polymorphism

Supplementary material

439_2009_649_MOESM1_ESM.doc (120 kb)
Supplementary figure and tables (DOC 120 kb)

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Candelaria Vergara
    • 1
    • 2
    • 4
  • Luis Caraballo
    • 1
    • 4
  • Dilia Mercado
    • 1
    • 4
  • Silvia Jimenez
    • 1
    • 4
  • Winston Rojas
    • 3
  • Nicholas Rafaels
    • 2
  • Tracey Hand
    • 2
  • Monica Campbell
    • 2
  • Yuhjung J. Tsai
    • 2
  • Li Gao
    • 2
  • Constanza Duque
    • 3
  • Sergio Lopez
    • 3
  • Gabriel Bedoya
    • 3
  • Andrés Ruiz-Linares
    • 3
    • 5
  • Kathleen C. Barnes
    • 2
  1. 1.Institute for Immunological ResearchUniversity of CartagenaCartagenaColombia
  2. 2.Department of Medicine, School of MedicineJohns Hopkins Allergy and Asthma CenterBaltimoreUSA
  3. 3.Laboratory of Molecular Genetics, Institute of BiologyUniversity of AntioquiaMedellínColombia
  4. 4.Foundation for the Development of Biological SciencesCartagenaColombia
  5. 5.Department of Genetics, Evolution and EnvironmentUniversity CollegeLondonUK