Adalimumab-responsive Monogenic Inflammatory Bowel Disease With Pseudopolyposis Characteristic of TGFBR2 Variant in Loeys-Dietz Syndrome.

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder caused by pathogenic variants in TGFBR1 or TGFBR2. It is characterized by vascular fragility, skeletal abnormalities, and predisposition to allergic and inflammatory conditions, including monogenic inflammatory bowel disease (IBD). We report a pediatric case of IBD with a TGFBR2 variant, presenting active colonic inflammation and pseudopolyposis, treated with adalimumab. At age 7, the patient presented with abdominal pain and bloody stools. Upon referral, colonoscopy demonstrated mucosal fragility, prominent pseudopolyposis, and an anal fissure, accompanied by a skin tag was identified. Genetic analysis revealed a heterozygous TGFBR2 c.1583G>A (p.Arg528His) variant and heterozygous MEFV E148Q and P369S-R408Q variants. Colchicine treatment for suspected familial Mediterranean fever-associated enteritis had a limited effect. Adalimumab treatment was initiated, leading to endoscopic improvement, with resolution of anemia and inflammatory markers in the blood test. This report presents the clinical course and endoscopic features potentially specific to the TGFBR2 c.1583G>A variant, with reference to previously published cases.