Knee Joint Swelling at Presentation: A Case of Pediatric Crohn Disease With a TNFAIP3 Mutation.

Crohn disease (CD) is a chronic inflammatory disease, and its incidence in children is rising. Despite extensive reports and investigations, the pathogenesis of CD has not been clearly elucidated, particularly in regard to triggering factors. A genetic predisposition is considered important when investigating the mechanism leading to CD, and the discovery of new CD-associated genes has increased our understanding of its immunopathogenesis and improved the efficacy of its treatment of CD. Early detection and treatment (eg, as children) with gene-based precision therapy can effectively prevent complications related to CD. In this case, a Chinese Han boy with CD associated with a mutation of tumor necrosis factor α-induced protein 3 was treated with recombinant human tumor necrosis factor-a receptor II:IgG Fc fusion protein. We suspected the boy had CD because of chronic abdominal pain, aphthous stomatitis, moderate anemia, a high erythrocyte sedimentation rate (36-79 mm/h), multiple intestinal ulcers, knee joint swelling, and a tumor necrosis factor α-induced protein 3 mutation. After total enteral nutrition and hormone therapy for 5 months, his abdominal pain and joint symptoms did not improve, so we started gene-based precision therapy with recombinant human tumor necrosis factor-a receptor II: IgG Fc fusion protein, which may play an important role in restricting TNF-α-induced NF-κB signaling. After 3 weeks, inflammation indicators were within the normal range, and multiple ulcers and joint symptoms were relieved. The present case demonstrates a safe therapeutic schedule that leads to rapid improvements in the clinical and biochemical status of patients with CD.