We report a family of French Canadian and Dutch ancestry with hereditary ferritinopathy (neuroferritinopathy) and a novel mutation (C insertion at nt646-647 in exon 4) in the ferritin light chain gene, resulting in a longer than normal protein. Our failure to immunostain most of the abnormal ferritin deposits in the proband with a conformation-dependent monoclonal antibody to ferritin light chain supported a previously postulated conformational change of ferritin light chain in this disease. The posterior putamen and cerebellum were the primary pathologic loci in our proband, but asymptomatic hepatocytic intranuclear accumulations of iron and ferritin also were present. Both neurons and glia displayed highly distinctive, if not pathognomonic, swollen to vacuolated nuclei containing ferritin and iron. Hyaline deposits, again staining for both ferritin and iron, were additional morphologic features that may be unique to the ferritinopathies. The iron, at least in putamen where there was a nearly 40-fold increase, appeared to be both in the ferrous (Fe2+) and ferric (Fe3+) form; it was the most likely cause of the observed neuronal and glial apoptosis. We found morphologic evidence of both lipid peroxidation and abnormal nitration of proteins in putaminal neurons and glia, confirming the expected oxidative stress due to this excessive iron. Biochemical and immunohistochemical abnormalities in mitochondria also were demonstrated, probably due to an imbalance in iron homeostasis that had a deleterious effect on the respiratory chain.

Two brothers with myopathic coenzyme Q10 (CoQ10) deficiency responded dramatically to CoQ10 supplementation. Muscle biopsies before therapy showed ragged-red fibers, lipid storage, and complex I + III and II + III deficiency. Approximately 30% of myofibers had multiple features of apoptosis. After 8 months of treatment, excessive lipid storage resolved, CoQ10 level normalized, mitochondrial enzymes increased, and proportion of fibers with TUNEL-positive nuclei decreased to 10%. The authors conclude that muscle CoQ10 deficiency can be corrected by supplementation of CoQ10, which appears to stimulate mitochondrial proliferation and to prevent apoptosis.

Background: Amyotrophic lateral sclerosis (ALS) is a major cause of neurological disability and its pathogenesis remains elusive despite a multitude of studies. Although defects of the mitochondrial respiratory chain have been described in several ALS patients, their pathogenic significance is unclear.Objective: To review systematically the muscle biopsy specimens from patients with typical sporadic ALS to search for possible mitochondrial oxidative impairment.

No abstract

We studied a large family with a dominantly inherited mitochondrial myopathy characterized by progressive external ophthalmoplegia, dysphagia, cataract, lactic acidosis, exercise intolerance, and early death. Morphologic studies of muscle biopsies suggested mitochondrial heteroplasmy and revealed ragged-red fibers and decreased histochemical reactions for cytochrome c oxidase and succinate dehydrogenase. Biochemistry showed a partial defect of cytochrome c oxidase and a mild generalized reduction of other mitochondrial enzymes requiring mitochondrial DNA-encoded subunits. Southern blot analysis and PCR amplification showed mitochondrial DNA deletions in muscle of all affected members, but not in lymphocytes or fibroblasts, suggesting a tissue-specific distribution. Deletions were multiple and seemed to increase with time and to correlate with the severity of the disease.