Complex sentence: Type 1 diabetes, rheumatoid arthritis, multiple sclerosis, and Crohn's disease are all examples of autoimmune diseases, which can be triggered when the body's immune system begins to attack healthy cells.
Split into simpler sentences: Type 1 diabetes, rheumatoid arthritis, multiple sclerosis, Crohn's disease. These are all examples of autoimmune diseases, which can be triggered when the body's immune system begins to attack healthy cells.