COLLAGEN TYPE-III GLOMERULOPATHY - A NEW-TYPE OF HEREDITARY NEPHROPATHY

A new type of hereditary glomerulopathy was observed in ten children p resenting with early and progressive glomerular symptoms, often associ ated with hypertension. Light microscopy showed a diffuse increase in the mesangial matrix and generalized widening of the capillary walls. Electron-microscopic examination of renal tissue, after phosphotungsti c acid treatment, revealed the presence of fibrillar collagen within t he mesangial matrix and the subendothelial aspect of the glomerular ba sement membrane, adjacent to normal lamina densa. Immunohistochemical studies identified the fibrillar collagen not usually present within t he glomerular extracellular matrix as type III collagen. Clinical and family studies ruled out the diagnosis of nail-patella syndrome, an au tosomal dominant disorder with typical extrarenal symptoms, which is a lso characterized by the presence of fibrillar collagen within the glo merular basement membranes. The poor renal outcome, the possible extra renal haematological and pulmonary involvement and the transmission as an autosomal recessive trait strongly suggest that collagen type III glomerulopathy is a new type of hereditary disease. From the high inci dence of superimposed haemolytic uraemic syndrome in patients or their siblings, it may be hypothetized that collagen type III glomerulopath y is the underlying defect in some of the familial cases of haemolytic uraemic syndromes.