Disorders of immune dysregulation
Gene: GPR15
GPR15 encodes a G protein‑coupled receptor that directs CD8⁺ regulatory T cells to the colon. PMID 42259915 reports 2 families with heterozygous truncating variants (p.Q281X, p.Y215X) presenting with early‑onset inflammatory bowel disease (IBD) in a dominant pattern. Affected carriers show variable penetrance (4/10; 40%), with some individuals mildly affected. Functional assays in patient T cells demonstrate reduced GPR15 surface expression, impaired Ca²⁺ signaling and defective chemotaxis, which is rescued by wild‑type GPR15; Gpr15‑null mice develop colitis, supporting a loss‑of‑function mechanism. PMID 42259915 also describes 2 families (1 mentioned above with both monoallelic and biallelic) with biallelic loss‑of‑function variants (compound heterozygous p.D306N/p.Q281X and homozygous p.Y215X) with severe early‑onset IBD (penetrance was partial in biallelic 3/4; 75%). Patient‑cell assays again show defective trafficking and signaling, restored by wild‑type rescue, and mouse models recapitulate colitis. One additional family homozygous for p.Y132S/p.F159I was excluded due to the high population frequency of p.Y132S. Suggested to be a possible hypomorph. Only 3 families contribute assessment, with suggested semidominant incomplete penetrance.
Sources: LiteratureCreated: 15 Jul 2026, 7:29 p.m.
Mode of inheritance
BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal
Phenotypes
inflammatory bowel disease MONDO:0005265
Publications
gene: GPR15 was added gene: GPR15 was added to Disorders of immune dysregulation. Sources: Expert Review Amber,Literature Mode of inheritance for gene: GPR15 was set to BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal Publications for gene: GPR15 were set to 42259915 Phenotypes for gene: GPR15 were set to inflammatory bowel disease MONDO:0005265