Diseases are often first recognized in their most severe forms. After a disease is initially described and diagnostic criteria are proposed, we gain experience and may broaden the spectrum to include manifestations that may be related but do not have all of the characteristics of a disease as originally described. Typical anti–glomerular basement membrane (GBM) disease is a clinically severe disease, with severe acute kidney injury, often pulmonary hemorrhage, and a high rate of end-stage kidney disease (and death if untreated).