Celiac disease is a chronic autoimmune condition in which gluten damages the lining of the small intestine and affects nutrient absorption. It is not a simple food allergy or intolerance — it is a serious disease requiring a strict lifelong gluten-free diet.
About 1% of the world population may be diagnosed; many cases remain undetected. The only current treatment is complete removal of gluten from the diet.
Reference: Celiac Disease Foundation