NOD2 and Crohn disease: For example, NOD2 (the most strongly associated Crohn’s disease susceptibility gene) can affect MHC class I responses through cross-presentation pathways, and in the presence of Crohn’s-associated NOD2 polymorphisms, these responses are dysregulated.92 ScRNA-seq has recently revealed the expansion of a CD8+ subpopulation expressing IL-17 in UC.8 However, the specific role of these subpopulations in the modulation of gut inflammation remains to be elucidated.