Early-onset nephrolithiasis and persistent microscopic hematuria in a child with a novel pathogenic COL4A5 variant in Alport syndrome: A case report and literature review

A 4-year-old male with persistent microscopic hematuria, hypocalciuria along with hypocitraturia. Renal ultrasound revealed bilateral microcalculi without structural anomalies. Ophthalmic and auditory evaluations were unremarkable. Family history indicated renal disease in the maternal aunt and maternal microscopic hematuria. Whole-exome sequencing (WES) identified a novel hemizygous nonsense variant in COL4A5 (NM_033380.3: c.1555C > T; p.Gln519*), truncating the protein at codon 519 of 1770. The variant, inherited from the mildly symptomatic mother (microscopic hematuria, right renal cyst), was absent in population databases and classified as pathogenic based on ACMG criteria (PVS1_Strong, PM2_Supporting, PP1_Supporting, PP4_Supporting). CytoScan 750 K array ruled out copy-number variations. This case expands the genotypic spectrum of Alport syndrome (AS), demonstrating an early presentation with nephrolithiasis, and underscores the diagnostic utility of WES in atypical inherited nephropathies.