Damgaard et al. [10] demonstrated that XIAP-BIR2 mutations abolish the XIAP-RIPK2 interaction, resulting in impaired ubiquitylation of RIPK2 and recruitment of linear ubiquitin chain assembly complex (LUBAC) to the NOD2 complex, which may explain why only one Chinese XIAP-deficient patient had IBD manifestations, since none of them had XIAP-BIR2 mutations. Here, RIPK2 is linked to inflammatory bowel disease.