Nephrin autoimmunity: signal, noise, and a path to clarity.

Advances in antigen discovery and autoantibody profiling have reshaped the classification of autoimmune kidney diseases, moving beyond purely histologic definitions. The identification of podocyte-targeting autoantibodies has transformed the understanding of nephrotic syndrome, prompting renewed interest in autoimmune mechanisms underlying podocytopathies. Recent reports of nephrin autoantibodies in minimal change disease, the most common cause of nephrotic syndrome in children, suggested a potential antigen-defined subset, but findings have been inconsistent. In this issue of the JCI, Pecoraro and colleagues advance the field by systematically interrogating anti-nephrin antibodies across a diverse nephrotic syndrome cohort using human-based and orthogonal approaches. Their results highlight critical limitations in assay specificity and cohort heterogeneity while raising the question of the clinical utility of anti-nephrin antibodies in the care of patients with minimal change disease. More broadly, this study underscores the need for collaboration to establish standardized assays and rigorously phenotyped cohorts.