Renal disease in Marfan syndrome.

We encountered 4 individuals with Marfan syndrome who presented with microhematuria and proteinuria. In 2 of them, a renal biopsy was performed. The predominant glomerular change by light microscopy was a focal segmental increase in mesangial matrix with early sclerotic lesions. Ultrastructurally, there was variable subendothelial widening containing haphazardly arranged microfibrils, 10-13 nm in diameter. Changes in small arteries present in the biopsies were mild in case 1 and more striking in case 2 which consisted of elastolysis and fragmentation and focal disruption of internal elastic lamina, and focal degenerative changes in the media. In light of observations on the abnormalities of microfibrillar protein (fibrillin) in the microfibrillar-fiber system and the presence of abnormal type IV collagen in the connective tissues in Marfan syndrome, the glomerular basement membrane alterations may be related to these defects and lead to microhematuria and proteinuria.