RESUMEN
Six boys and six girls aged under 3 years with asymptomatic hematuria and/or proteinuria were found and renal biopsies were performed from 1 month to 10 years after the discovery. Light microscopy uncovered 4 cases of focal segmental glomerulosclerosis (FSGS), 3 cases of diffuse mild mesangial proliferation, and 5 cases of minor glomerular abnormalities. Immunofluorescent studies did not show any significant depositions. Electron microscopy revealed diffuse thinning of the glomerular basement membrane (GBM) in 2 cases, and segmental thinning of the GBM in 8 cases, including 2 cases of FSGS found in the light microscopy. Four cases, including 2 cases of FSGS, had irregular thickening of the GBM and splitting of the lamina densa. Two cases of FSGS did not have GBM abnormalities. The significance of GBM abnormalities in children with asymptomatic hematuria and/or proteinuria under 3 years of age needs to further evaluated.