Dataset Information

Admixture in Hispanic Americans: its impact on ITGAM association and implications for admixture mapping in SLE.

ABSTRACT: Systemic Lupus Erythematosus (SLE) disproportionately affects minorities, such as Hispanic Americans (HA). Prevalence of SLE is 3-5 times higher in HA than in European-derived populations and have more active disease at the time of diagnosis, with more serious organ system involvement. HA is an admixed population, it is possible that there is an effect of admixture on the relative risk of the disease. This admixture can create substantial increase of linkage disequilibrium (LD) in both magnitude and range, which can provide a unique opportunity for admixture mapping. The main objectives of this study are to (a) estimate hidden population structure in HA individuals; (b) estimate individual ancestry proportions and its impact on SLE risk; (c) assess impact of admixture on ITGAM association, a recently identified SLE susceptibility gene; and (d) estimate power of admixture mapping in HA. Our dataset contained 1125 individuals, of whom 884 (657 SLE cases and 227 controls) were self-classified as HA. Using 107 unlinked ancestry informative markers (AIMs), we estimated hidden population structure and individual ancestry in HA. Out of 5671 possible pairwise LD, 54% were statistically significant, indicating recent population admixture. The best-fitted model for HA was a four-population model with average ancestry of European (48%), American-Indian (AI) (40%), African (8%) and a fourth population (4%) with unknown ancestry. We also identified significant higher risk associated with AI ancestry (odds ratio (OR)=4.84, P=0.0001, 95% CI (confidence interval)=2.14-10.95) on overall SLE. We showed that ITGAM is associated as a risk factor for SLE (OR=2.06, P=8.74 x 10(-5), 95% CI=1.44-2.97). This association is not affected by population substructure or admixture. We have shown that HA have great potential and are an appropriate population for admixture mapping. As expected, the case-only design is more powerful than case-control design, for any given admixture proportion or ancestry risk ratio.

SUBMITTER: Molineros JE

PROVIDER: S-EPMC2714406 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Admixture in Hispanic Americans: its impact on ITGAM association and implications for admixture mapping in SLE.

Molineros J E JE Kim-Howard X X Deshmukh H H Jacob C O CO Harley J B JB Nath S K SK

Genes and immunity 20090423 5

Systemic Lupus Erythematosus (SLE) disproportionately affects minorities, such as Hispanic Americans (HA). Prevalence of SLE is 3-5 times higher in HA than in European-derived populations and have more active disease at the time of diagnosis, with more serious organ system involvement. HA is an admixed population, it is possible that there is an effect of admixture on the relative risk of the disease. This admixture can create substantial increase of linkage disequilibrium (LD) in both magnitude ...[more]

PMID: 19387459

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Project description:Short-acting ?2-adrenergic receptor agonists (SABAs) are the most commonly prescribed asthma medications worldwide. Response to SABAs is measured as bronchodilator drug response (BDR), which varies among racial/ethnic groups in the United States. However, the genetic variation that contributes to BDR is largely undefined in African Americans with asthma. To identify genetic variants that may contribute to differences in BDR in African Americans with asthma, we performed a genome-wide association study (GWAS) of BDR in 949 African-American children with asthma, genotyped with the Axiom World Array 4 (Affymetrix, Santa Clara, CA) followed by imputation using 1000 Genomes phase III genotypes. We used linear regression models adjusting for age, sex, body mass index (BMI) and genetic ancestry to test for an association between BDR and genotype at single-nucleotide polymorphisms (SNPs). To increase power and distinguish between shared vs. population-specific associations with BDR in children with asthma, we performed a meta-analysis across 949 African Americans and 1830 Latinos (total?=?2779). Finally, we performed genome-wide admixture mapping to identify regions whereby local African or European ancestry is associated with BDR in African Americans. We identified a population-specific association with an intergenic SNP on chromosome 9q21 that was significantly associated with BDR (rs73650726, p?=?7.69?×?10-9). A trans-ethnic meta-analysis across African Americans and Latinos identified three additional SNPs within the intron of PRKG1 that were significantly associated with BDR (rs7903366, rs7070958 and rs7081864, p???5?×?10-8). Our results failed to replicate in three additional populations of 416 Latinos and 1615 African Americans. Our findings indicate that both population-specific and shared genetic variation contributes to differences in BDR in minority children with asthma, and that the genetic underpinnings of BDR may differ between racial/ethnic groups.

Dataset Information

Admixture in Hispanic Americans: its impact on ITGAM association and implications for admixture mapping in SLE.

Publications

Admixture in Hispanic Americans: its impact on ITGAM association and implications for admixture mapping in SLE.

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