This is a type of hereditary nephritis known as Alport syndrome in which patients may also manifest nerve deafness and eye problems. The glomeruli show irregular thickening and thinning and splitting of basement membranes due to an inherited abnormality in collagen. Most cases are X-linked and have mutations of the COL4A5 gene. In addition, as shown below, the renal tubular cells appear foamy because of the accumulation of neutral fats and mucopolysaccharides.