Project description:The goal of this study was to identify functional variants that play a role in exfoliation syndrome (XFS) pathogenesis. We sequenced the entire LOXL1 locus in 50 South African XFS cases and 50 matched controls. The most strongly associated variants in this dataset were found in a ~7kb region spanning the LOXL1 exon 1/intron 1 boundary. DNase hypersensitivity analysis was used to demonstrate that this region, which lies upstream of the LOXL1 antisense RNA (LOXL1-AS1), contains regulatory activity. determining of chromatin structural changes in 3 cell types.
Project description:The goal of this study was to identify functional variants that play a role in exfoliation syndrome (XFS) pathogenesis. We sequenced the entire LOXL1 locus in 50 South African XFS cases and 50 matched controls. The most strongly associated variants in this dataset were found in a ~7kb region spanning the LOXL1 exon 1/intron 1 boundary. DNase hypersensitivity analysis was used to demonstrate that this region, which lies upstream of the LOXL1 antisense RNA (LOXL1-AS1), contains regulatory activity.
Project description:<p>The overall goal of our research is to elucidate the pathogenesis of exfoliation syndrome and the associated glaucoma, making it possible to implement effective screening and prevention strategies and to develop novel therapies. Cases genotyped for this project are from the Nurses Health Study (NHS), the Health Professionals Follow-up Study (HPFS), the Women's Genome Health Study (WGHS), the Massachusetts Eye and Ear Infirmary (MEEI), Mayo Clinic, the University of Iowa, the University of Miami and Duke University Medical Center.</p> <p>Exfoliation syndrome (XFS) is a common condition that is a major risk factor for high-tension open-angle glaucoma, pre-mature cataract formation, and increased risk of complications during cataract surgery. Previous studies suggest that exfoliation syndrome and the related glaucoma (XFG) are genetically complex, and one gene, LOXL1, has been identified as a major genetic risk factor. LOXL1 variants are found in up to 98% of affected patients; however, these same variants are also present in up to 80% of unaffected individuals, indicating that additional genetic and/or environmental factors are necessary for disease development.</p> <p>Samples genotyped for this study are a case set (1,096 samples) and 24 pedigrees (98 samples). Controls for association analyses are selected from the NEIGHBORHOOD study. </p>
Project description:Exfoliation syndrome (XFS) is a condition characterized by the production of insoluble fibrillar aggregates (exfoliation material; XFM) in the eye and elsewhere. Many patients with XFS progress to exfoliation glaucoma (XFG), a significant cause of global blindness. We used quantitative mass spectrometry to analyze the composition of XFM in lens capsule specimens and aqueous humor samples from XFS and XFG patients and individuals without XFS. Pieces of lens capsule and samples of aqueous humor were obtained with consent from patients undergoing cataract surgery. Tryptic digests of capsule or aqueous samples were analyzed by HPLC-mass spectrometry and relative differences between samples were quantified using the tandem mass tag technique. The distribution of XFM on the capsular surface was visualized by scanning electron microscopy and super-resolution light microscopy. A small set of proteins was consistently upregulated in XFS samples, including microfibril components fibrillin-1 (FBN1), latent TGFBeta-binding protein-2 (LTBP-2), and LTBP-3. Lysyl oxidase-like 1 (LOXL1), a protein linked strongly to XFS in genetic studies, was an abundant XFM protein. Ligands of the TGFBeta superfamily were prominent, including LEFTY2, a protein known for its role in establishing the embryonic body axis. Elevated levels of LEFTY2 were also detected in aqueous humor from XFG patients and confirmed by ELISA. This analysis verified the presence of several suspected XFM proteins and identified novel components. Quantitative comparisons between patient samples revealed a consistent XFM proteome. The expression of FBN1, LOXL1, and LEFTY2 was particularly strong in XFG patients in comparison to XFS patients.
Project description:Coronary artery disease (CAD) is the most common cardiovascular disease and the leading cause of death worldwide. To date, the 9p21.3 locus is the most robust and frequently replicated risk locus of CAD among >90 CAD risk loci identified by GWAS. More than 50 CAD-associated genomic variants were identified at the 9p21.3 CAD locus and many of them are located within a long non-coding gene ANRIL, which was initially referred to as Antisense Non-coding RNA in INK4 Locus. The causal role of ANRIL in CAD and the underlying molecular mechanism are unknown. We used gene expression microarray to identify the downstream target genes of ANRIL and to explore molecular mechanisms by which ANRIL might contribute to the risk development of CAD.
Project description:Objective - The TRIB1 locus has been linked to hepatic triglyceride metabolism in mice and to plasma triglycerides and coronary artery disease (CAD) in humans. The lipid associated SNPs identified by genome-wide association studies (GWAS) are located ~ 30 kb downstream from TRIB1 suggesting complex regulatory effects on genes or pathways relevant to hepatic triglyceride metabolism. The goal of this study was to investigate the functional relationship between common SNPs at the TRIB1 locus and plasma lipid traits. Methods & Results - Characterization of the risk locus reveals that it encompasses a gene, TRIB1 associated locus (TRIBAL) comprised of a well conserved promoter region and an alternatively spliced transcript. Bioinformatic analysis and re-sequencing identified a single nucleotide polymorphism (SNP), rs2001844, within the promoter region that associates with increased plasma triglycerides, reduced HDL-C and CAD risk. Furthermore, we show that rs2001844 is an expression trait locus (eQTL) for TRIB1 expression in blood and alters TRIBAL promoter activity in a reporter assay model. The TRIBAL transcript has features typical of long noncoding RNAs (lncRNA), including poor sequence conservation. Modulation of TRIBAL expression had limited impact on either TRIB1 or lipid regulatory genes mRNA levels in human hepatocyte models. In contrast, TRIB1 knockdown markedly increased TRIBAL expression in HepG2 cells and primary human hepatocytes. Conclusions - These studies demonstrate an interplay between a novel locus,TRIBAL, and TRIB1. TRIBAL is located in the GWAS identified risk locus, responds to altered expression of TRIB1, harbors a risk SNP that is an eQTL for TRIB1 expression and associates with plasma triglyceride concentrations. Transcriptome changes to TRIBAL downregulation (48 h) Huh7 were exposed to non-target or TRIBAL-specific antisense oligonucleotides for 48 h in normal (low glucose DMEM, 10% serum, Pen-Strep)
Project description:A major goal of genetics research is to elucidate mechanisms explaining how genetic variation contributes to phenotypic variation. The genetic variants identified in genome-wide association studies (GWASs) generally explain only a small proportion of heritability of phenotypic traits, the so-called missing heritability problem. Recent evidence suggests that additional common variants beyond lead GWAS variants contribute to phenotypic variation; however, their mechanistic underpinnings generally remain unexplored. Herein, we undertake a study of haplotype-specific mechanisms of gene regulation at 8p23.1 in the human genome, a region associated with a number of complex diseases. The FAM167A-BLK locus in this region has been consistently found in the genome-wide association studies (GWASs) of systemic lupus erythematosus (SLE) in all major ancestries. Our haplotype-specific chromatin interaction (Hi-C) experiments, allele-specific enhancer activity measurements, genetic analyses, and epigenome editing experiments revealed that: (1) haplotype-specific long-range chromatin interactions are prevalent in 8p23.1; (2) BLK promoter and cis-regulatory elements cooperatively interact with haplotype-specificity; (3) genetic variants at distal regulatory elements are allele-specific modifiers of the promoter variants at FAM167A-BLK; (4) the BLK promoter interacts with and, as an enhancer-like promoter, regulates FAM167A expression and (5) local allele-specific enhancer activities are influenced by global haplotype structure due to chromatin looping. Although SLE causal variants at the FAM167A-BLK locus are thought to reside in the BLK promoter region, our results reveal that genetic variants at distal regulatory elements modulate promoter activity, changing BLK and FAM167A gene expression and disease risk. Our results suggest that global haplotype-specific 3-dimensional chromatin looping architecture has a strong influence on local allelic BLK and FAM167A gene expression, providing mechanistic details for how regional variants controlling the BLK promoter may influence disease risk.
Project description:There is growing evidence for the inherited basis of susceptibility to childhood acute lymphoblastic leukemia (ALL). Genome-wide association studies have identified non-coding ALL risk variants at the ARID5B gene locus, but their exact functional effects and the molecular mechanism linking ARID5B to B-ALL leukemogenesis remain largely unknown. In this study, by targeted sequencing in germline DNA of 5,008 children with ALL, we identified 31 common variants in ARID5B significantly associated with leukemia risk, all of which were non-coding. Six cis-regulatory elements at the ARID5B locus were discovered using CRISPR-based high-throughput enhancer screening. Strikingly, the top ALL risk variant (rs7090445, P=1.82×10-10) is located precisely within the strongest enhancer element, which is also distally tethered to the ARID5B promoter. The rs7090445 variant allele disrupts the MEF2C binding motif sequence, resulting in reduced MEF2C affinity and decreased local chromosome accessibility. MEF2C influences ARID5B expression in ALL, likely via a transcription factor complex with RUNX1. Using the UK Biobank dataset (n=349,861), we showed that rs7090445 was also associated with lymphocyte percentage and count in the general population (P=8.6×10-22 and 2.1×10-18, respectively). Taken together, our results indicate that ALL risk variants in ARID5B function by modulating cis-regulatory elements at this locus.
Project description:A large portion of common variant loci associated with genetic risk for schizophrenia reside within non-coding sequence of unknown function. Here, we demonstrate promoter and enhancer enrichment in schizophrenia variants associated with expression quantitative trait loci (eQTL). The enrichment is greater when functional annotations derived from human brain are used relative to peripheral tissues. Regulatory trait concordance analysis ranked genes within schizophrenia genome-wide significant loci, based on co-localization of a risk SNP, eQTL and regulatory element sequence. These include physical interactions of non-contiguous gene-proximal and distal elements bypassing the linear genome, which was verified in prefrontal cortex and human induced pluripotent stem cell derived neurons for the L-type calcium channel (CACNA1C) risk locus. Our findings point to a functional link between schizophrenia-associated non-coding SNPs and 3-dimensional genome architecture associated with chromosomal loopings and transcriptional regulation in the brain. Examination of H3K4me3 histone modifications in 3 samples.
Project description:Genome-wide association studies (GWAS) have boosted our knowledge of genetic risk variants in autoimmune diseases (AIDs). Most of the risk variants are located within or near genes with immunological functions, and the majority is found to be non-coding, pointing towards a regulatory role. We have performed a cis expression quantitative trait locus (eQTL) screen to investigate whether single nucleotide polymorphisms (SNPs) associated with AIDs influence gene expression in thymus. Genotyping was performed using the Immunochip and 353 AID associated SNPs were tested against expression of surrounding genes (+/- 1 Mb) from human thymic tissue (N=42). We identified eight genes where the expression was associated with AID risk SNPs at a study-wide level of significance (P < 2.57x10-5). Five genes (FCRL3, RNASET2, C2orf74, SIRPG and SYS1) displayed cis eQTL signals also in other tissues, while for two loci (NPIPB8 and LOC388814), the eQTL signal appear to be thymus-specific. Since many AID risk variants from GWAS have been subsequently fine-mapped in recent Immunochip projects, we explored the overlap between these novel AID risk variants and the thymic eQTL regions. Moreover, we examined the functional annotation of the seven expression altering SNPs (eSNPs). Our study reveals autoimmune risk variants that act as eQTLs in thymus. We have highlighted functional variants within these genetic regions that potentially can represent causal autoimmune risk variants. Total RNA from 42 human thymic samples were obtained from children undergoing cardiac surgery.