IL23R encodes a subunit of the interleukin-23 receptor that associates with IL12RB1 to form the functional IL-23 receptor complex 1. The receptor binds IL-23 and mediates signaling in T cells, NK cells, and certain macrophage/myeloid cells through the JAK-STAT pathway 1. Functionally, IL23R signaling promotes Th17 cell differentiation and inflammatory responses, playing crucial roles in both innate and adaptive immunity. Structural studies reveal that IL23R shares IL-12Rβ1 with the IL-12 receptor through a non-canonical topology where IL-12Rβ1 directly engages the common p40 subunit 1. Disease-wise, IL23R is strongly associated with inflammatory bowel diseases, particularly Crohn's disease, where specific variants like rs11209026 confer protection against disease development 2. In Crohn's disease, expansion of apoptosis-resistant TNFR2+IL23R+ T cells is associated with resistance to anti-TNF therapy 3. Additionally, IL23R variants show associations with coronary artery disease through gene-gene interactions 4 and multiple sclerosis susceptibility 5. Clinically, IL23R represents a promising therapeutic target, with IL23R-specific CAR Tregs showing potential for treating active Crohn's disease 6, and IL-23R levels serving as biomarkers of aging and senescence 7.