Anti-GBM antibody–mediated glomerulonephritis usually presents with rapidly progressive glomerulonephritis. In some patients, the antibody cross-reacts with alveolar basement membranes, and about half also have hemoptysis due to lung involvement. This constellation of kidney and lung disease is called Goodpasture syndrome. The incidence in the United States is about one per million per year. Patients show a bimodal age distribution (peaks at the late teens to age 20, and at 50-70 years old), with equal distribution by sex.