title: Immunogenetics of rheumatoid arthritis: Understanding functional implications.
abstract: The last decade has seen a dramatic technological revolution. The characterisation of the majority of the common variations in our genetic code in 2003 precipitated the discovery of the genetic risk factors predisposing to Rheumatoid Arthritis development and progression. Prior to 2007, only a handful of genetic risk factors had been identified, HLA, PTPN22 and CTLA4. Since then, over 100 genetic risk loci have been described, with the prediction that an ever-increasing number of risk alleles with consistently decreasing effect sizes will be discovered in the years to come. Each risk locus harbours multiple candidate genes and the proof of causality of each of these candidates is as yet unknown. An enrichment of these RA-associated genes is found in three pathways: T-cell receptor signalling, JAK-STAT signalling and the NF-κB signalling cascade, and currently drugs targeting these pathways are available for the treatment of RA. However, the role that RA-associated genes have in these pathways and how they contribute to disease is not always clear. Major efforts in understanding the contribution of genetic risk factors are currently under way with studies querying the role of genetic variation in gene expression of coding and non-coding genes, epigenetic marks and other regulatory mechanisms yielding ever more valuable insights into mechanisms of disease. Recent work has suggested a possible enrichment of non-coding RNAs as well as super-enhancers in RA genetic loci indicating possible new insights into disease mechanism. This review brings together these emerging genetic data with an emphasis on the immunogenetic links these findings have provided and what we expect the future will bring.
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, Netherlands; Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Tobias C
authors.initials: TC
authors.lastname: Messemaker
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, Netherlands. Electronic address: t.w.j.huizinga@lumc.nl.
authors.forename: Tom W
authors.initials: TW
authors.lastname: Huizinga
authors.affiliation: Department of Rheumatology, Leiden University Medical Center, Leiden, Netherlands. Electronic address: b.a.s.kurreeman@lumc.nl.
authors.forename: Fina
authors.initials: F
authors.lastname: Kurreeman
mesh_terms: D000818:Animals; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D015551:Autoimmunity; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D056426:Genetic Loci; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D006680:HLA Antigens / Q000235:genetics / Q000276:immunology; D006801:Humans; D007125:Immunogenetics; D022661:RNA, Untranslated / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D015398:Signal Transduction
chemical_list: D006680:HLA Antigens; D022661:RNA, Untranslated
keywords: Autoimmunity; GWAS; Genetics; Non-coding RNA; Rheumatoid arthritis