Celiac disease is an autoimmune intestinal inflammatory disorder caused by an intolerance to gluten. It involves damage to the mucosa of the small intestine, deterioration of the microvilli, and nutrient malabsorption. NCGS is a milder form of gluten intolerance that can still cause symptoms. While classical symptoms of celiac disease still occur after eating gluten, sufferers have normal small intestine biopsies and negative antibody tests.