FOXP3 and arthritic joint disease: In addition, in human studies, signs of arthritis were observed in only a few cases of X‐linked syndrome of immune dysregulation, polyendocrinopathy, and enteropathy (IPEX), a disease that develops in individuals with a FOXP3 gene mutation 21, 22; instead, patients with IPEX present with thrombocytopenia, insulin‐dependent diabetes mellitus, diarrhea, or thyroiditis 22.