Dataset Information

GEI Studies - Psoriasis

ABSTRACT:

The GEI Studies Project was started as an NIH consortium involving 5 disease groups with funding provided through the Genes, Environment, and Health Initiative (GEI). The objective of the project was to optimize strategies for identifying rare variants as a follow up to genome-wide association studies (GWAS) using next-generation sequencing technology. One of the five targeted diseases, Psoriasis, is a multifactorial skin disease characterized by epidermal hyperproliferation and chronic inflammation that affects approximately 2% of Americans. Because only about one-third of all patients with psoriasis have a relative who is also affected with the disorder, psoriasis is not widely recognized as a genetic disease. However, previous research on families and identical twins has shown psoriasis has a strong genetic component, although environmental factors (such as infections, stress, and injuries) are also important. Although no definite psoriasis gene has yet been identified, research during the last ten years has revealed over forty potential gene locations that may contribute to the disease. Large amounts of data generated using next-generation sequencing technology would provide a more detailed characterization of sequence variation which would in turn increase the likelihood of detecting causative loci. With the presumption that rare variants are frequently the cause of a large portion of phenotypic variation, it was necessary to use large sample sets. In the main body of this study, we sequenced 4,966 samples (812 dermatologist-diagnosed cases of purely cutaneous psoriasis (PsC), 1,497 cases of rheumatologist-diagnosed psoriatic arthritis, 665 cases of cutaneous psoriasis with uncertain psoriatic arthritis status (PsV) and 1,992 controls) across 5.7 Mb of sequence containing 100 psoriasis candidate loci and 769 genes. For each candidate locus, we considered sequences within 250 kb of the strongest association signal. Within this window, three strategies were employed. For ten of the strongest psoriasis signals, we used a whole-region approach which included non-coding intergenic and intronic sequence. For four established loci of lesser significance, we targeted all full transcription units within the +/- 250 kb interval. For the remaining signals, we targeted the exons of all transcription units within the +/- 250 kb interval. Due to complexities of high-efficiency targeting of HLA genes we selected 5 specific candidate genes for sequencing near the HLA-C gene.

PROVIDER: phs000766 | dbGaP |

SECONDARY ACCESSION(S): PRJNA253636PRJNA253635

REPOSITORIES: dbGaP

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Dataset's files

Source:

			Action	DRS
	GapExchange_phs000766.v1.p1.xml	Xml
	dbGaPEx2.1.5.xsd	Other
	Study_Report.phs000766.GEI_Psoriasis.v1.p1.MULTI.pdf	Pdf
	manifest_phs000766.GEI_Psoriasis.v1.p1.c1.GRU.pdf	Pdf
	datadict_v2.xsl	Other

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Project description:Psoriasis is a common, immune-mediated, genetic disorder of the skin associated with arthritis in approximately 30% of cases. Previously, we localized PSORS2 (psoriasis susceptibility locus 2) to chromosome 17q25.3-qter following a genome-wide linkage scan in a family of European origin with multiple cases of psoriasis and psoriatic arthritis. Linkage to PSORS2 was also observed in a multiply affected psoriasis family from Taiwan. With genomic capture and DNA sequencing, we identified unique gain-of-function mutations in caspase recruitment domain family, member 14 (CARD14) that segregated with psoriasis. The mutations, c.349G>A (p.Gly117Ser) and c.349+5G>A respectively, altered splicing between exons 3 and 4 of CARD14. A de novo mutation in CARD14, c.413A>C [p.Glu138Ala], was detected in a child with sporadic, early-onset, generalized pustular psoriasis. CARD14 activates nuclear factor kappa B (NF-kB), and the p.Gly117Ser and p.Glu138Ala substitutions were shown to lead to enhanced NF-kB activation and upregulation of a subset of psoriasis-associated genes in keratinocytes compared to wildtype CARD14. These included chemokine (C-C motif) ligand 20 (CCL20) and interleukin 8 (IL8). CARD14 is localized mainly in the basal and suprabasal layers of healthy skin epidermis, while in lesional psoriatic skin it is reduced in the basal layer and more diffusely upregulated in the suprabasal layers of the lesional epidermis. We propose that, following a triggering event that can include epidermal injury, rare gain-of-function mutations in CARD14 initiate a process that includes inflammatory cell recruitment by keratinocytes. This perpetuates a vicious cycle of epidermal inflammation and regeneration that is the hallmark of psoriasis. No replicates are included. Three sample sets. [1] Skin biopsies had RNA extracted for expression within target tissue. [2] HEK cells were transfected with different constructs (including wildtype) of CARD14 to determine the mutational effect in keratinocytes. [3] Keratinocytes derived from psoriasis patients with CARD14 mutations were cultured and compared with and without stimulation with TNFalpha.

Project description:Background: Although genome-wide association studies (GWAS) have identified hundreds of variants associated with risk of autoimmune and immune-related disorders (AID), our understanding of the diseases mechanisms is limited. In particular, more than 90% of the risk variants lie in non-coding regions, and almost 10% of these map to long non-coding RNA transcripts (lncRNAs). LncRNAs are known to show more cell-type specificity than protein-coding genes. Methods: In this study, we aimed to characterize lncRNAs and protein-coding genes located in loci associated with nine AID which have been well-defined by Immunochip analysis, by transcriptome analysis across seven peripheral blood leukocyte populations (granulocytes, monocytes, NK cells, B-cells, memory-T cells, naive CD4+ and naive CD8+ T-cells) and four cord blood derived T-helper cell populations (precursor, primary, polarized (Th1, Th2) T-helper cells). Results: We show that lncRNAs mapping to loci shared between AIDs are significantly enriched in immune cell types when compared to lncRNAs from the whole genome (M-NM-1<0.005). We were not able to prioritize single cell types relevant for specific diseases, but we observed five cell types enriched (M-NM-1<0.005) in five AID (NK cells for inflammatory bowel disease, juvenile idiopathic arthritis, primary biliary cirrhosis, psoriasis; memory-T and CD8+ T-cells in juvenile idiopathic arthritis, primary biliary cirrhosis, psoriasis, rheumatoid arthritis; Th0 and Th2 cells for inflammatory bowel disease, juvenile idiopathic arthritis, primary biliary cirrhosis, psoriasis, rheumatoid arthritis). Furthermore we show that co-expression analyses of lncRNAs and protein-coding genes can predict the signaling pathways in which these AID-associated lncRNAs are involved. Conclusions: The observed enrichment of lncRNA transcripts in AID loci implies an important role for lncRNAs in AID etiology and suggests that lncRNA genes should be studied in more detail to correctly interpret GWAS findings. The co-expression results strongly support a model in which the lncRNA and protein-coding genes function together in the same pathways. 7 immune cell types

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GEI Studies - Psoriasis

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