Celiac disease is an autoimmune disease where the immune system attacks the small intestine in response to gluten. It is genetic and can be triggered by environmental factors like surgery or stress. Symptoms include abdominal pain, diarrhea, and weight loss. There is no cure, but following a strict gluten-free diet for life can help manage symptoms and heal intestinal damage. Celiac affects about 1 in 133 Americans and is more common in people of European descent.