Impact of genetic risk loci for multiple sclerosis on expression of proximal genes in patients

Tojo James, Magdalena Lindén, Hiromasa Morikawa, Sunjay Jude Fernandes, Sabrina Ruhrmann, Mikael Huss, Maya Brandi, Fredrik Piehl, Maja Jagodic, Jesper Tegner, Mohsen Khademi, Tomas Olsson, David Gomez-Cabrero, Ingrid Kockum

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Despite advancements in genetic studies, it is difficult to understand and characterize the functional relevance of disease-associated genetic variants, especially in the context of a complex multifactorial disease such as Multiple Sclerosis (MS). Since a large proportion of expression quantitative trait loci (eQTLs) are context-specific, we performed RNA-Seq in peripheral blood mononuclear cells (PBMCs) from MS patients (n=145) to identify eQTLs in regions centered on 109 MS risk SNPs and seven associated HLA variants. We identified 77 statistically significant eQTL associations, including pseudogenes and non-coding RNAs. Thirty-eight out of 40 testable eQTL effects were colocalised with the disease association signal. Since many eQTLs are tissue specific, we aimed to detail their significance in different cell types. Approximately 70% of the eQTLs were replicated and characterized in at least one major PBMC derived cell type. Furthermore, 40% of eQTLs were found to be more pronounced in MS patients compared to noninflammatory neurological diseases patients. In addition, we found two SNPs to be significantly associated with the proportions of three different cell types. Mapping to enhancer histone marks and predicted transcription factor binding sites added additional functional evidence for eight eQTL regions. As an example, we found that rs71624119, shared with three other autoimmune diseases and located in a primed enhancer (H3K4me1) with potential binding for STAT transcription factors, significantly associates with ANKRD55 expression. This study provides many novel and validated targets for future functional characterization of MS and other diseases.
Original languageEnglish (US)
Pages (from-to)912-928
Number of pages17
JournalHuman Molecular Genetics
Volume27
Issue number5
DOIs
StatePublished - Jan 8 2018

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