Project description:Background: Asthma, a complex chronic lung disease affecting the airways, has striking disparities across ancestral groups, but the molecular underpinning of these differences is poorly understood and minimally studied. A major goal of the Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to understand multi-omics signatures of asthma risk in the nasal epithelium focusing on populations of African ancestry. Methods: DNA methylation (DNAm) quantification was performed using Illumina’s Infinium MethylationEPIC array® using genomic DNA from nasal airway epithelial cells collected across the 4 US recruitment sites (Baltimore, Chicago, Denver, and Washington DC) for 331 subjects (N=149 asthma cases, N= 182 never asthmatic controls). We performed association analysis to identify eQTMs (CpG-gene associations) for DEGs limiting to CpGs ≤5kb from the transcription start site or within enhancer regions identified through promoter-capture HiC in bronchial epithelial cells. CpGs from significant eQTMs (p<0.05) were tested for differential methylation by asthma (DMCs) to assess the relative contribution of expression and methylation in asthma risk. All models were fully adjusted for ancestry, sampling site, and appropriate latent factors. Findings: Multi-omic analysis identified FKBP5 as a key contributor to asthma risk, where the association between nasal epithelium gene expression is likely regulated by methylation and is associated with increased use of inhaled corticosteroids. FKBP5 is a co-chaperone of glucocorticoid receptor signaling and known to be involved in drug response in asthma. Interpretation: Our analyses reveal genes and networks in asthma that are differentially expressed in nasal epithelium of current asthma cases of African ancestry in CAAPA. Importantly, this work reveals molecular dysregulation on three axes – increased Th2 inflammation, decreased capacity for wound healing, and impaired drug response – that may play a critical role in asthma within the African Diaspora.
Project description:Background: Asthma, a complex chronic lung disease affecting the airways, has striking disparities across ancestral groups, but the molecular underpinning of these differences is poorly understood and minimally studied. A major goal of the Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to understand multi-omics signatures of asthma risk in the nasal epithelium focusing on populations of African ancestry. Methods: RNASeq data were generated from nasal epithelium in subjects recruited from up to 7 sites (Baltimore, Washington DC, Chicago, Denver, Salvador Brazil, Barbados, and Nigeria). Current asthma cases (N=253) were compared to never-asthma controls (N=283) to identify differentially expressed genes (DEGs; q <0.05). Network analyses were performed with Ingenuity Pathway Analysis (IPA; DEGs with q<0.05) and weighted gene co-expression network analysis (WGCNA; DEGs with q<0.15). All models were fully adjusted for ancestry, sampling site, and appropriate latent factors. Findings: CAAPA represents diversity across the African Diaspora with a wide range of continental African ancestry (9%-100%). We identified 389 DEGs; the top DEG, FN1, was downregulated in asthma cases (q=3.26x10-9) and encodes fibronectin which plays a role in wound healing. Others in the top 10 DEGs have high relevance for asthma: SNTG2 (q = 1.12x10-4) is the target of multiple miRNAs related to asthma; PPP1R9A expression (q=7.60x10-5) was previously determined to be influenced by IL-13 in mouse lung; and SPTBN1 (q=1.12x10-4) plays a key role in mediating TGFβ signaling. IPA revealed networks with upstream regulators relevant for immune response (IL4; p=7.25x10-10 and TGFβ1; p=5.47x10-8) and drug response (dexamethasone; p=4.31x10-10 and fluticasone propionate; p=9.42x10-8). Among asthma cases, genes regulated by dexamethasone and fluticasone propionate were not associated with inhaled corticosteroid medication use. The top three WGCNA modules implicate networks related to immune response (CEACAM5; p=9.62x10-16 and CPA3; p=2.39x10-14) and wound healing (FN1; p=7.63x10-9). Multi-omic analysis identified FKBP5 as a key contributor to asthma risk, whereby the association between nasal epithelium gene expression is mediated through methylation and is associated with increased use of inhaled corticosteroids. FKBP5 is a co-chaperone of glucocorticoid receptor signaling and known to be involved in drug response in asthma. Interpretation: Our analyses reveal genes and networks in asthma that are differentially expressed in nasal epithelium of asthma cases of African ancestry in CAAPA. Importantly, this work reveals molecular dysregulation on three axes – increased Th2 inflammation, decreased capacity for wound healing, and impaired drug response – that may play a critical role in asthma within the African Diaspora.
Project description:<p>Asthma is a complex disease where the interplay between genetic factors and environmental exposures influences susceptibility and disease prognosis. Asthmatics of African descent tend to have more severe asthma and more severe clinical symptoms than individuals of European ancestry. Advances in genetic and genomic technologies have revolutionized gene discovery for several complex diseases, but going to the next step in gene discovery for asthma among populations of African descent requires considering unique characteristics of this ethnic group, including adequate sample sizes and population stratification due to (European and African) admixture. Thus far, coverage of common genetic markers both in public databases and commercially available SNP chips has been inadequate to detect and measure genetic associations among African admixed populations. The aim of this study was therefore to catalog genetic diversity in populations of African descent, especially those whose ancestry reflects the African Diaspora in the Americas.</p>
Project description:Characterization of ancestry-linked peptide variants in disease-relevant patient tissues represents a foundational step to connect patient ancestry with molecular disease pathogenesis. Nonsynonymous single nucleotide polymorphisms (SNPs) encoding missense substitutions within tryptic peptides exhibiting high allele frequencies in European, African, and East Asian populations, termed peptide ancestry informative markers (pAIMs), were prioritized from 1000 genomes. In silico analysis shows that as few as 20 pAIMs can determine ancestry proportions similarly to >260K SNPs (R2=0.9905). Multiplexed proteomic analysis of >100 human endometrial cancer cell lines and uterine leiomyoma (ULM) tissues combined resulted in the quantitation of 62 pAIMs that correlate with self-described race and genotype-confirmed patient ancestry. Candidates include a D451E substitution in GC vitamin D-binding protein previously associated with altered vitamin D levels in African and European populations. These efforts describe a generalized set of markers for proteoancestry assessment that will further support studies investigating the impact of ancestry on the human proteome and how this relates to the pathogenesis of uterine neoplasms.
Project description:Women of sub-Saharan African descent have disproportionately higher incidence of Triple Negative Breast Cancer (TNBC), and TNBC-specific mortality. Population comparative studies show racial differences in TNBC biology, including higher prevalence of basal-like and Quadruple-Negative subtypes in African Americans (AA). However, previous investigations relied on self-reported race (SRR) of primarily United States (US) populations. Due to heterogenous genetic admixture, and biological consequences of social determinants, the true association of African ancestry with TNBC biology is unclear. To address this, we conducted RNAseq on an international cohort of AAs, west and east Africans with TNBC. Using comprehensive genetic ancestry estimation in this African-enriched cohort, we found expression of 613 genes associated with African ancestry and 2000+ associated with regional African ancestry. A subset of African-associated genes also showed differences in normal breast tissue. Pathway enrichment and deconvolution of tumor cellular composition revealed tumor-associated immunological profiles are distinct in patients of African descent.
Project description:Study of genes that are differentially spliced and differentially expressed between African Americans and whites with lung squamous cell cancer. Despite racial disparities in lung cancer, the molecular landscape of lung cancer in patients of African ancestry remains underexplored. Population-related differences in alternative RNA splicing have not been explored. We identified differentially spliced genes and differentially expressed genes between lung squamous cell carcinoma from patients of West African and European ancestry.
Project description:The genetic structure of some native Bolivians has been substantially influenced by admixture from Europeans, which we estimate to have occurred approximately 360 – 384 years ago. Consistent with historical accounts of male admixture, Y-chromosome haplogroups typical of Europeans were found in 39% of our Bolivian samples. No evidence of African admixture was found in native Bolivians. The Mesoamerican Totonacs have little evidence of European or African admixture. Our analysis indicates that some admixed Bolivians have Native American mtDNA and Y-chromosomes but harbor up to 30% European autosomal ancestry, demonstrating the need for autosomal markers to assess ancestry in admixed populations. From a dense genome-wide panel of 815,377 markers, we developed a set of 324 AIMs, specific for Native American ancestry. As few a 40-50 of these markers successfully predict New World ancestry in the ascertainment panel of Bolivians and Totonacs. The markers easily distinguish New World from Old World ancestry, even for populations more closely related to the Americas such as central and eastern Asians, and were effective for New World vs. Old World comparisons in five other geographically and culturally distinct populations of the Americas. SNPs demonstrating very high divergence between the two Native American populations and major Old World populations are found on haplotypes that are shared and occur at similar frequencies in other indigenous low-admixture American populations examined here (i.e. Pima, Maya, Colombian, Karitiana, and Surui). After excluding the possibility of recent relatedness, our results indicate that native Bolivians and Totonacs share ancestry with other American populations through a substantial contribution from a common founding population, population bottlenecks, and possible natural selection on functional variation.
Project description:Variation in gene expression is a fundamental aspect of human phenotypic variation. Several studies have analyzed gene expression levels in populations of different continental ancestry, and concluded that there is variation across populations at a fraction of expressed genes. Here we analyze gene expression levels in African American cell lines, which differ from previously analyzed cell lines in that samples from this population have variable proportions of continental ancestry. We show that for most genes examined, gene expression varies with genetic ancestry. Keywords: Human Gene Expression Study
Project description:Differences in microRNAs have not been well studied as potential mechanisms underlying the breast cancer disparity. A number of miRNAs were differentially expressed not only by tumor subtype but by ancestry, indicating differences in tumor biology of breast cancer between women of African and European ancestry. Findings may contribute to a better understanding of the biology of breast cancer disparities and help develop more targeted preventative and therapeutic strategies.