In addition to NOD2, other genetic risk factors that may affect Paneth cell function in Crohn's disease include mutations in ATG16L1 (160), which is part of the autophagy pathway and implicated in Paneth cell degranulation, or in the transcription factor X-box binding protein-1 (Xbp1), a key regulator of the endoplasmic reticulum (ER) stress response (161). The gene discussed is XBP1; the disease is Crohn disease.