IL12A and inflammatory bowel disease: The IL23 receptor shares the protein encoded by IL12RB1 but also requires IL23R. Similarly, the ligands bound by these receptors, IL12 and IL23, are composed by shared subunits: IL12 is encoded by IL12A and IL12B, while IL23 is encoded by IL23A and IL12B. Interestingly, celiac disease is associated with IL12A [42,43] and thereby differs from IBD and psoriasis, where IL12B variants have shown risk effect.