Figure 1.

Flowchart of the pilot, discovery, and validation cohorts. Initial pilot studies were done by mass spectrometry studies using 15 PLA2R-negative MN and seven PLA2R-positive MN cases. After detection of EXT1/EXT2 in five cases confirmed by IHC, we studied a large number (n=209) of PLA2R-negative MN cases and controls (n=95) for expression of EXT1/EXT2 by IHC. Controls included 13 cases of proliferative lupus nephritis (LN) without a membranous component and 40 cases of PLA2R-positive MN. Finally, we studied 48 cases of MN in a validation cohort that included PLA2R-negative primary MN (pMN), membranous (class 5) LN, and mixed class LN with a membranous component. *One case (patient #16) started with pure MN with signs of autoimmunity and then shifted to mixed class. Neg, negative; pos, positive.