Renal pathology and ultrastructural findings in Alport's syndrome

Abstract

Morphological study of the kidney is generally the first step in the diagnosis of Alport's syndrome. Light microscopy study allows to suggest the diagnosis with the association of focal and segmental glomerulosclerosis, GBM anomalies when studied with silver staining, interstitial foam cells, and negative standard immunofluorescence study. GBM anomalies observed by electron microscopy are nearly specific with thickening splitting and fragmenting of the lamina densa. GBM anomalies are the consequence of a collagen IV disease. Thus, immunohistochemical results obtained with 6 different α(IV) are essential and allow to evaluate the mode of inheritance. Schematically, in the X dominant AS form, GBM, distal tubular BM and collecting duct BM do not express α3/α4, α5(IV). In the autosomic recessive AS form, collecting duct BM alone express α5(IV) without expression of α3(IV) and α5(IV) chains along the GBM and distal TBM.