Monogenic Inflammatory Bowel Disease Due to Novel SMAD7 Mutation

Very early-onset inflammatory bowel disease (IBD) has a higher proportion (10%-15%) of monogenic mutations than later onset IBD. With next-generation sequencing (NGS), newer disease-causing mutations are being revealed. We report a 4-year-old girl presenting with chronic bloody diarrhea and failure to thrive, and diagnosed as Crohn's disease. Whole-exome sequencing by NGS revealed a novel pathogenic mutation in mothers against decapentaplegic homolog 7 (SMAD7) gene. She responded to biologics. Monogenic disorders should be suspected in children with very early-onset IBD with poor response to standard immunosuppression, and NGS should be performed. SMAD7 provides a new target for in-depth research for its role in IBD.