Psoriasis, psoriatic arthritis (PsA) and inflammatory bowel disease (IBD) are multifactorial chronic immunoinflammatory disorders with characteristic common genetic markers that determine their common pathophysiology and similar immune abnormalities. In particular, IL12/23 signaling pathway of the immune pathogenesis of the above mentioned diseases is related to the IL23R gene polymorphism. Common pathophysiological features, in their turn, produce a high risk and prevalence of comorbidity. Clinicians' unawareness of these particulars of the immunoinflammatory disorders might lead to the absence of interdisciplinary collaboration, late diagnosis of one of these disorders and polypharmacy, because each specialist...