Adult-Onset Focal Segmental Glomerulosclerosis Associated with CRB2 Gene Variants, a Case Report

Abstract

Focal segmental glomerulosclerosis (FSGS) is a common pathological lesion in kidney biopsies with diverse etiologies, including genetic mutations.<br /> We report a case of a 39-year-old man presenting with proteinuria of 2 g/day, normal kidney function, and no nephrotic syndrome. A kidney biopsy revealed findings consistent with FSGS (not otherwise specified )NOS( type), and whole-exome sequencing (WES) identified two heterozygous variants in the CRB2 gene: c.3219C>G (likely pathogenic) and c.1864G>A (variant of uncertain significance). The patient was managed conservatively with renin-angiotensin-aldosterone system (RAAS) inhibitor and Sodium-Glucose cotransporter 2 (SGLT2) inhibitor, resulting in sustained proteinuria reduction and preservation of kidney function over a three-year follow-up. This report highlights a possible novel presentation of CRB2 mutation-associated FSGS without steroid resistance or nephrotic syndrome, that was successfully managed without immunosuppression.