Goodpasture syndrome is a rare but serious autoimmune disease that attacks the lungs and kidneys. The disease occurs when the body's immune system mistakenly produces antibodies against collagen in the lungs and kidneys. Collagen is a protein that helps form connective tissue. Goodpasture syndrome initially causes vague symptoms such as fatigue. But it can rapidly involve the lungs and kidneys. It is almost always fatal if it is not quickly diagnosed and treated.