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.

Gun Violence, African Ancestry, and Asthma

“…[7][8][9][10][11][12][13] In a recent study of 5,493 Hispanic children and adults (including Puerto Ricans), each 20% increment in African ancestry increased the odds of asthma by 40% (95% CI, 1.14-1.72; P ¼ .001). 8 Similar associations have been demonstrated in African American, Colombian, and Brazilian adults.…”

“…8 Similar associations have been demonstrated in African American, Colombian, and Brazilian adults. [9][10][11] For example, each 10% increment in African ancestry was associated with a 16% increment in the odds of asthma in a case-control study of 796 African American adults (95% CI, 1.06-1.28; P ¼ .002). 11 African ancestry has been associated with higher total or allergen-specific IgEs in some but not all previous reports.…”

“…7,8 Indeed, several studies have shown that African ancestry is associated with an increased risk of asthma and/or reduced lung function in Puerto Ricans and African Americans. [7][8][9][10][11][12][13][14] Exposure to violence is common among Puerto Rican and African American children 4,[15][16][17][18] and could thus partly explain the observed link between African ancestry and asthma. Exposure to violence is increasingly being recognized as a potentially modifiable risk factor for childhood asthma.…”

Genetics and Asthma Disease Susceptibility in the US Latino Population

“…17 The concepts of race and ethnicity include connotations that reflect culture, history, socioeconomics, linguistics, and political status, although race has been considered to be characterized by the primary continent of origin. 17 -20 Recent studies that assess the relationship of self-reported race and genetic ancestry with allergic sensitization in a non-Latino population provide conflicting data about the importance of the use of race/ethnicity; in one study, selfreported African American race was associated with allergic sensitization, asthma, and high total serum immunoglobulin E (IgE) levels, 21 whereas in another study, the association with allergic sensitization was not significant after researchers accounted for the location of residence. 22 The study of genetics is even more complex and difficult when the study population is admixed, that is, contains race and ethnic mixtures.…”

The Peopling of the Bahamas: A Phylogeographical Perspective

“…Delta (δ) values for each of the 15 STR loci were also computed (Listman et al, 2007) for the grouped East versus West African collections to ascertain marker information content, i.e., the ability of the Identifiler loci to differentiate between the two groups of populations. Any locus yielding a δ value ≥ 0.30 (Vergara et al, 2009) is considered informative for discriminating between the two sources.…”