Biallelic cubilin pathogenic variants as a cause of « benign » proteinuria: implications for clinical management

The recent description of a cohort with both adults and children harboring biallelic pathogenic variants of CUBN changed the paradigm of the management of isolated proteinuria. Indeed, the detection of proteinuria in a patient, regardless of age, often leads to an exhaustive check-up including kidney biopsy but also the prescription of renin-angiotensin system (RAS) blockers to slow the progression of kidney disease. Patients with CUBN variants have nondetrimental proteinuria and are non-responsive to RAS blockers. We herein describe 2 siblings treated for isolated proteinuria for several years, eventually diagnosed with CUBN biallelic pathogenic variants (c.703 C > T and c.10363-3A > G). We review the physio-pathological mechanisms of this newly discovered disease and discuss implications for clinical management.