[Thin basement membrane and Alport syndrome].
Alport Syndrome (AS) is an inherited disorder of the glomerular basement membrane (GBM) transmitted as an X-linked dominant form in approximately 80% of patients. This X-linked form is caused by mutations in the collagen type IV alfa 5 gene (COL4A5) located on chromosome X; in the remainder of the cases, the autosomal, mostly recessive form, results from mutations in the collagen type IV alfa 3 gene (COL4A3) or alfa 4 gene (COL4A4) located on the 2q. Diagnostic lesions can be observed by electron microscopy (EM) and are characterized by thinning, thickening and/or splitting of the GBM. Isolated thinning of the GBM is usually associated with isolated microhematuria, a non progressive condition which has often a familial trait. Skin biopsy has also recently emerged to be a valuable alternative for the diagnosis of X-linked AS, because the alfa 5 (COL4A5) chain is also expressed in the epidermal basement membrane. A reliable diagnosis can often be achieved through combined renal and cutaneous immunohistochemical analysis, even in patients with limited clinical signs or atypical histological findings, and/or without suggestive family history. The present case report is an example of such diagnostic dilemma, where these techniques allowed to make a diagnosis despite contradictive clinical and histological features in contrast with a positive family history of renal disease.
Massella
L
L
Dipartimento di Nefro-Urologia, Divisione di Nefrologia e Dialisi, Ospedale Bambino Gesù - IRCCS, Roma - Italy.
Emma
F
F
Onetti Muda
A
A
D000293:Adolescent; D050533:Glomerular Basement Membrane / Q000473:pathology; D006801:Humans; D008297:Male; D009394:Nephritis, Hereditary / Q000175:diagnosis*