title: Alport's syndrome: specificity and pathogenesis of glomerular basement membrane alterations.
abstract: In Alport's syndrome (AS) thinning and splitting of the glomerular basement membrane (GBM) are assumed to be characteristic ultrastructural alterations. Both lesions are, however, non-specific because they can occur in other glomerulopathies. In addition, splitting may be found in non-glomerular structures. It should be emphasized that the characteristic lesion in AS is a result of the widespread combination of thin and split GBM in the same biopsy specimen. In our opinion the basic lesion is the thin GBM, which is characterized by a lamina densa (measuring 50-150 nm in thickness) which may begin to split as a result of focal detachment of podocyte pedicles (spacing) and repeated subepithelial deposition of new lamina densa layers. Splitting thus appears to be a secondary lesion. Thinning of GBM may represent a persistent embryonal status of the lamina densa and may thus be the result of a development defect. This assumption is supported by the findings of fetal-like glomeruli and small capillary loops in AS.
authors.affiliation: Pathologisches Institut der Universität Mainz, Federal Republic of Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Rumpelt
mesh_terms: D001485:Basement Membrane / Q000648:ultrastructure; D006801:Humans; D007678:Kidney Glomerulus / Q000473:pathology* / Q000648:ultrastructure; D009394:Nephritis, Hereditary / Q000473:pathology*