CUBN and megaloblastic anemia: This study aimed to clarify the genetic and clinical characteristics of chronic benign proteinuria and the molecular basis distinguishing it from IGS.<h4>Methods</h4>We evaluated patients with proteinuria carrying biallelic <i>CUBN</i> variants identified through targeted panel sequencing and investigated molecular mechanisms underlying the phenotypic differences between IGS and chronic benign proteinuria.<h4>Results</h4>Fifty-two patients from 42 families were analyzed, and 40 <i>CUBN</i> variants, including 30 novel variants, were identified.