Functional variants of the interleukin-23 receptor gene in non-gastrointestinal autoimmune diseases

Variants of the gene of the interleukin-23 receptor (IL23R) were first identified as susceptibility factors in association with inflammatory bowel diseases. Since then it became clear that different variants of the gene play also role in a number of other autoimmune diseases like psoriasis, rheumatoid arthritis, ankylosing spondylitis and multiple sclerosis while in others, like systemic sclerosis, systemic lupus erythematosus or Sjögren syndrome the same effect could not be seen. However, the results are very controversial both in terms of the various polymorphisms and also in population specificity. The aim of the current paper is to overview all available reports on IL23R gene polymorphisms in various autoimmune and inflammatory diseases and to try to give an explanation on the possible effect of the examined variants.