New familial nephropathy involving glomerular and tubular basement membranes

We describe two siblings, an 8-year-old boy and a 9-year-old girl, with severe mental retardation, dwarfism, optic atrophy and nephropathy. Laboratory examination showed beta 2-microglobulinuria, decreased creatinine clearance, hypercholesterolaemia and elevated serum levels of muscle enzymes. Renal biopsy from one of the patients demonstrated characteristic ultrastructural changes involving both the glomerular and tubular basement membrane. This group of symptoms and laboratory findings is quite distinct and differs from those of other reported familial nephropathy syndromes. We conclude that this disorder may represent a new syndrome of autosomal recessive inheritance.