Dataset Information

Desmoplakin Variants Are Associated with Idiopathic Pulmonary Fibrosis.

ABSTRACT: Sequence variation, methylation differences, and transcriptional changes in desmoplakin (DSP) have been observed in patients with idiopathic pulmonary fibrosis (IPF).To identify novel variants in DSP associated with IPF and to characterize the relationship of these IPF sequence variants with DSP gene expression in human lung.A chromosome 6 locus (7,370,061-7,606,946) was sequenced in 230 subjects with IPF and 228 control subjects. Validation genotyping of disease-associated variants was conducted in 936 subjects with IPF and 936 control subjects. DSP gene expression was measured in lung tissue from 334 subjects with IPF and 201 control subjects.We identified 23 sequence variants in the chromosome 6 locus associated with IPF. Genotyping of selected variants in our validation cohort revealed that noncoding intron 1 variant rs2744371 (odds ratio?=?0.77, 95% confidence interval [CI]?=?0.66-0.91, P?=?0.002) is protective for IPF, and a previously described IPF-associated intron 5 variant (rs2076295) is associated with increased risk of IPF (odds ratio?=?1.36, 95% CI?=?1.19-1.56, P?

SUBMITTER: Mathai SK

PROVIDER: S-EPMC4872666 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Desmoplakin Variants Are Associated with Idiopathic Pulmonary Fibrosis.

Mathai Susan K SK Pedersen Brent S BS Smith Keith K Russell Pamela P Schwarz Marvin I MI Brown Kevin K KK Steele Mark P MP Loyd James E JE Crapo James D JD Silverman Edwin K EK Nickerson Deborah D Fingerlin Tasha E TE Yang Ivana V IV Schwartz David A DA

American journal of respiratory and critical care medicine 20160501 10

<h4>Rationale</h4>Sequence variation, methylation differences, and transcriptional changes in desmoplakin (DSP) have been observed in patients with idiopathic pulmonary fibrosis (IPF).<h4>Objectives</h4>To identify novel variants in DSP associated with IPF and to characterize the relationship of these IPF sequence variants with DSP gene expression in human lung.<h4>Methods</h4>A chromosome 6 locus (7,370,061-7,606,946) was sequenced in 230 subjects with IPF and 228 control subjects. Validation g ...[more]

PMID: 26669357

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Project description:Idiopathic pulmonary fibrosis (IPF) is a devastating disease that probably involves several genetic loci. Several rare genetic variants and one common single nucleotide polymorphism (SNP) of MUC5B have been associated with the disease. Our aim was to identify additional common variants associated with susceptibility and ultimately mortality in IPF.First, we did a three-stage genome-wide association study (GWAS): stage one was a discovery GWAS; and stages two and three were independent case-control studies. DNA samples from European-American patients with IPF meeting standard criteria were obtained from several US centres for each stage. Data for European-American control individuals for stage one were gathered from the database of genotypes and phenotypes; additional control individuals were recruited at the University of Pittsburgh to increase the number. For controls in stages two and three, we gathered data for additional sex-matched European-American control individuals who had been recruited in another study. DNA samples from patients and from control individuals were genotyped to identify SNPs associated with IPF. SNPs identified in stage one were carried forward to stage two, and those that achieved genome-wide significance (p<5?×?10(-8)) in a meta-analysis were carried forward to stage three. Three case series with follow-up data were selected from stages one and two of the GWAS using samples with follow-up data. Mortality analyses were done in these case series to assess the SNPs associated with IPF that had achieved genome-wide significance in the meta-analysis of stages one and two. Finally, we obtained gene-expression profiling data for lungs of patients with IPF from the Lung Genomics Research Consortium and analysed correlation with SNP genotypes.In stage one of the GWAS (542 patients with IPF, 542 control individuals matched one-by-one to cases by genetic ancestry estimates), we identified 20 loci. Six SNPs reached genome-wide significance in stage two (544 patients, 687 control individuals): three TOLLIP SNPs (rs111521887, rs5743894, rs5743890) and one MUC5B SNP (rs35705950) at 11p15.5; one MDGA2 SNP (rs7144383) at 14q21.3; and one SPPL2C SNP (rs17690703) at 17q21.31. Stage three (324 patients, 702 control individuals) confirmed the associations for all these SNPs, except for rs7144383. Linkage disequilibrium between the MUC5B SNP (rs35705950) and TOLLIP SNPs (rs111521887 [r(2)=0·07], rs5743894 [r(2)=0·16], and rs5743890 [r(2)=0·01]) was low. 683 patients from the GWAS were included in the mortality analysis. Individuals who developed IPF despite having the protective TOLLIP minor allele of rs5743890 carried an increased mortality risk (meta-analysis with fixed-effect model: hazard ratio 1·72 [95% CI 1·24-2·38]; p=0·0012). TOLLIP expression was decreased by 20% in individuals carrying the minor allele of rs5743890 (p=0·097), 40% in those with the minor allele of rs111521887 (p=3·0?×?10(-4)), and 50% in those with the minor allele of rs5743894 (p=2·93?×?10(-5)) compared with homozygous carriers of common alleles for these SNPs.Novel variants in TOLLIP and SPPL2C are associated with IPF susceptibility. One novel variant of TOLLIP, rs5743890, is also associated with mortality. These associations and the reduced expression of TOLLIP in patients with IPF who carry TOLLIP SNPs emphasise the importance of this gene in the disease.National Institutes of Health; National Heart, Lung, and Blood Institute; Pulmonary Fibrosis Foundation; Coalition for Pulmonary Fibrosis; and Instituto de Salud Carlos III.

Project description:Rationale: To identify functionally relevant common genetic risk variants associated with idiopathic pulmonary fibrosis (IPF), we performed expression quantitative trait loci (eQTL) and methylation quantitative trait loci (mQTL) mapping, followed by co-localization of eQTL and mQTL with genetic association signals as well as mediation analysis. Methods: Illumina MEGA genotyping arrays, mRNA sequencing, and Illumina 850k methylation arrays were performed on lung tissue of participants with IPF (234 RNA and 345 DNA samples) and non-diseased control (188 RNA and 202 DNA samples). Transcriptome and methylome datasets were normalized for unknown batch effects using Probabilistic Estimation of Expression Residuals (PEER). eQTL, cell type-interaction eQTL, and mQTL analyses were performed in FastQTL and co-localization analysis in eCAVIAR separately for cases and controls. Benjamini-Hochberg false discovery rate was used for adjustment for multiple comparisons. Results: After appropriate adjustment, we identified 4,745 genes with significant eQTLs in controls and 6,047 in cases (FDR-adjusted p<0.05). Focusing on genetic variants within 10 primary IPF-associated genetic loci, we identified 27 eQTLs in controls and 24 eQTLs in cases (FDR-adjusted p<0.05). Among these signals, we identified association of rs35705950 with expression of MUC5B (Chr11 locus) and rs2076295 with expression of DSP (Chr6 locus) in both cases and controls. To address cell specificity, we performed cell type-interaction eQTL analysis and identified an association of rs2076295 with expression of DSP in smooth muscle cells. mQTL analysis identified CpGs in gene bodies of MUC5B (cg17589883) and DSP (cg08964675) associated with the lead variants in these two loci. eCAVIAR demonstrated strong co-localization of eQTL/mQTL and genetic signal in MUC5B (rs35705950) and DSP (rs2076295) in both cases and controls. Mediation analysis demonstrated partial mediation of the effect of common variants in MUC5B and DSP loci on disease risk though MUC5B and DSP gene expression. Functional validation of the mQTL in MUC5B demonstrates that the CpG is within a putative internal repressor element that interacts through a 3D loop with the enhancer containing the rs35705950 genetic variant. Conclusions: Using lung eQTL/mQTL, co-localization, and mediation analyses, we have established the functional validation of the common IPF genetic risk variants for MUC5B (rs35705950) and DSP (rs2076295). These results provide additional evidence that both MUC5B and DSP are involved in the etiology of IPF.

Dataset Information

Desmoplakin Variants Are Associated with Idiopathic Pulmonary Fibrosis.

Publications

Desmoplakin Variants Are Associated with Idiopathic Pulmonary Fibrosis.

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