Alport syndrome diagnosed by immunofluorescence using a new monoclonal antibody.

A 14-year-old female with microscopic hematuria was admitted for a renal biopsy. She had a family history of renal disease without deafness. The findings of light microscopy and conventional immunofluorescence were normal. Electron microscopy showed a diffuse thinning of the glomerular basement membrane (GBM) with its mild splitting. Irregular thickening of GBM and glomerular small dense particles was not observed. Thin basement membrane syndrome was suspected from these findings. However, it was difficult to differentiate from Alport syndrome. Immunofluorescence analysis using the monoclonal antibody to the 28-kilodalton monomers of the noncollagenous domain of type IV collagen verified the diagnosis of heterozygous Alport syndrome.