Ultrastructural abnormalities of liver tissue were similar in the 9 patients studied. A, Liver biopsy from patient 7 at the age of 13 months shows canalicular dilatation, subtotal effacement of microvilli, a pericanalicular collar of microfilaments, and intact desmosomes. Canalicular bile is finely granular. Inset: Another severely dilated canaliculus in this patient contains occasional coarse aggregates mixed with the finely granular bile. Osmium tetroxide/uranyl acetate/lead citrate stain (× 3150). B, Liver biopsy from patient 11 at the age of 3 years shows mild mitochondrial pleomorphism, with alterations in size, shape, and matrix density. Osmium tetroxide/uranyl acetate/lead citrate stain (× 2000).