Accumulation of mitochondrial ATP synthase subunit c in muscle in a patient with neuronal ceroid lipofuscinosis (late infantile form).

We report a case late infantile neuronal ceroid lipofuscinosis (NCL). Abnormal granules were found in the skeletal muscle fibers, Schwann cells, perineurial cells, endothelial cells, fibroblasts, and perivascular smooth muscle cells in the sural nerve. Electron microscopy revealed that these granules showed fingerprint profiles, curvilinear profiles or membrane-bound membranous structures. Acid phosphatase reaction was increased in these cells. Immunohistochemical studies for mitochondrial ATP synthase subunit c showed a strong reaction in these cells, suggesting abnormal accumulation of subunit c. Immunohistochemistry for subunit c in muscle may be useful in the diagnosis of late infantile NCL.