Induction of colitis resulted in increased disease severity in the Fndc4 KO mice, as shown by increased disease severity index (Fig. 8c), reduced colon length (Fig. 8d), increased body weight loss (Fig. 8e), increased histopathology scores (Fig. 8f,g) and increased proinflammatory gene expression (Fig. 8h). This evidence concerns the gene FNDC4 and colitis.