PTPN2 and Crohn disease: While the first AIEC was discovered in ileal tissues of a Crohn’s disease patient, several other AIEC strains have been discovered from other intestinal regions.16,39–41mAIEC is present in low levels in wild-type mice but displayed much higher abundance in constitutive Ptpn2-KO mice in both the small and large intestine.18 Of note, in this current study mAIECred preferentially colonized the distal colon versus more proximal regions of the intestine.