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1/61. A novel mutation (8342G-->A) in the mitochondrial tRNA(Lys) gene associated with progressive external ophthalmoplegia and myoclonus.

    We describe a patient who suffered from impaired ocular motility from age 10 years and at 16 years developed ptosis, proximal weakness and progressive fatigability. At 35 years she developed massive myoclonic jerks, and head and distal tremor. A muscle biopsy showed a high percentage of cytochrome c oxidase negative fibers but no ragged-red fibers. A novel heteroplasmic mutation (8342G-->A) was found in the mitochondrial transfer rna(Lys) gene by single-strand conformation polymorphism screening, followed by sequence and restriction fragment length polymorphism analysis. Approximately 80% of muscle mitochondrial dna (mtDNA) harbored the mutation, while the mutation was absent in lymphocyte dna of the proband, as well as of her mother, daughter and a maternal aunt. However, the pathogenicity of the mutation was confirmed by restriction fragment length polymorphism analysis of single muscle fibers, which revealed a significantly greater level of mutant mtDNA in cytochrome c oxidase negative over cytochrome c oxidase positive fibers. ( info)

2/61. Autosomal dominant progressive external ophthalmoplegia: distribution of multiple mitochondrial dna deletions.

    OBJECTIVE: To relate signs and symptoms to morphologic changes and presence of multiple mitochondrial dna (mtDNA) deletions in a patient with autosomal dominant progressive external ophthalmoplegia (adPEO) and mitochondrial myopathy. BACKGROUND: An etiologic association between the somatic multiple mtDNA deletions in adPEO and clinical manifestations other than the myopathy has so far not been demonstrated. methods: The authors investigated a patient with adPEO and multiorgan system manifestations including levodopa-responsive parkinsonism. She died at age 61 years of pancreatic carcinoma. autopsy tissue specimens were investigated for morphologic alterations and occurrence of mtDNA deletions by Southern blot and long-extension PCR analyses. RESULTS: The patient had carcinoma of the pancreas with metastases to liver, lymph nodes, and bone marrow. The brain revealed slight gliosis of the gray and white matter and degeneration of the substantia nigra. The myocardium showed focal areas with loss and atrophy of myocytes and fibrosis. Analysis of mtDNA revealed multiple deletions in different regions of the brain, skeletal muscle, and myocardium. Twenty-five different mtDNA deletions were identified. Most of these were flanked by large direct-sequence repeats. Six identical deletions were found in muscle and brain. CONCLUSIONS: These findings indicate that somatic multiple mtDNA deletions are associated with degenerative tissue changes and clinical manifestations in adPEO. ( info)

3/61. cochlear implantation for symptomatic hereditary deafness.

    Recently, the effectiveness of cochlear implantation for hereditary deafness has been reported. We performed cochlear implantation for two patients with symptomatic hereditary deafness. deafness in one patient was thought to be a result of albinism-deafness syndrome and in the other patient, a result of chronic progressive external ophthalmoplegia syndrome. Since their speech perception abilities improved dramatically, we believe that cochlear implantation should be actively performed for these two syndromes. ( info)

4/61. mitochondrial diseases represent a risk factor for valproate-induced fulminant liver failure.

    We report on 3 siblings (2 females and 1 male) with chronic progressive external ophthalmoplegia (CPEO), compatible with inherited mitochondrial cytopathy. The younger of the two sisters died at the age of 37 due to progressive respiratory failure. The older one presented with a status epilepticus at the age of 39 and was treated with valproate. Five months after the start of treatment, she developed fulminant liver failure and died. The brother has suffered from CPEO since early childhood but has had so far no other symptoms of a mitochondrial disease. A muscle biopsy from the younger sister revealed ragged-red fibers and decreased activities of complex I and IV of the respiratory chain but no pathogenic mutations in the mitochondrial tRNA genes or in several locations in the coding region of the mitochondrial genome. In the older sister's liver (obtained post-mortem), mitochondrial dna was fragmented and could not be investigated. The clinical presentation and the biochemical findings suggest that all 3 siblings suffered from a mitochondrial cytopathy. Since mitochondrial cytopathies and valproate-induced fulminant liver failure are both rare events, an association between them is likely. mitochondrial diseases should therefore be considered as a risk factor for valproate-induced liver failure and be excluded before treatment with valproate. ( info)

5/61. Chronic exposure keratopathy complicating surgical correction of ptosis in patients with chronic progressive external ophthalmoplegia.

    PURPOSE: To report chronic exposure keratopathy related to surgical ptosis correction in patients with chronic, progressive, external ophthalmoplegia. methods: case reports of three patients with chronic exposure keratopathy following blepharoptosis surgery. RESULTS: We report three patients with chronic progressive external ophthalmoplegia with chronic corneal complications after surgical ptosis repair. All three gave a history of blepharoptosis and extraocular muscle dysfunction. Each presented with chronic corneal ulceration. All had histories suggestive of ophthalmoplegia. Treatment of corneal ulceration necessitated hospitalization and surgical intervention. CONCLUSION: patients with chronic, progressive, external ophthalmoplegia have little ability to properly protect the eye from exposure and are at risk for corneal damage. A thorough ophthalmic history and examination before ptosis surgery may prevent the corneal complications resulting from surgical intervention. ( info)

6/61. Ultrastructural analysis of extraocular muscle in chronic progressive external ophthalmoplegia.

    Extraocular muscles are primarily involved in many mitochondrial diseases, but no reports exist regarding the morphological appearance of the muscles in cases of long-standing ocular myopathies. For this reason, muscle samples obtained from surgery in a sporadic case of chronic progressive external ophthalmoplegia (CPEO) were used for ultrastructural investigation and molecular analysis of mitochondrial dna. genetic testing revealed a heteroplasmic macrodeletion of about 5.0 kilobases in length, localized between the 9570- and 14619-base pair regions. Electron microscopy revealed focal areas of both disruption and abnormality of mitochondria in only some of the muscle fibers, producing "selective vacuolization." This ultrastructural pattern was highly selective and limited to some extraocular muscle fibers, sparing all the others. The "selective damage" observed in this case of CPEO resembles that case occurring in another mitochondrial disease, Leber hereditary optic neuropathy, where damage occurs only in the papillomacular bundle of the retina, sparing peripheral axons. It is possible that some anatomical and physiological factors play a leading role in both Leber hereditary optic neuropathy and ocular myopathies. The ultrastructural aspect herein observed needs to be further investigated to better understand whether a particular muscle fiber type is the target of mitochondrial impairment in CPEO. ( info)

7/61. A unique junctional palindromic sequence in mitochondrial dna from a patient with progressive external ophthalmoplegia.

    A polymerase chain reaction (PCR) based procedure was modified to determine the deletion of mitochondrial dna (mtDNA). The protocol consists of coamplification both of deleted and wild-type segments of mtDNA using a long PCR technique; evaluation of the deleted portion within the amplified dna segments by restriction enzyme digestion followed by densitometrical analysis; and direct subcloning into a plasmid vector for dna sequencing. The procedure revealed a 5.3 kb deletion of mtDNA in the biopsied muscle tissue obtained from a patient clinically diagnosed with progressive external ophthalmoplegia. The 5' and 3' sequences at both sides of the breakpoint comprise a 17 bp palindrome and 5 bp tandem repeats, suggesting that the deletion might occur through slipped mispairing and other novel mechanisms. This improved procedure has the potential to detect deletions occurring in the entire length of mtDNA, and mighty be useful for clinical screening of progressive external ophthalmoplegia. ( info)

8/61. Abnormal H-Tfam in a patient harboring a single mtDNA deletion.

    We report on a patient suffering from a progressive mitochondrial disorder characterized by ocular myopathy, exercise intolerance, and muscle wasting. Morphological examination of muscle biopsy showed increased variability in fiber size and scattered ragged-red fibers. Analysis of muscle mitochondrial dna by Southern blot and PCR revealed a heteroplasmic single deletion of 4100 base pairs, located between nucleotide positions 8300 and 12,400. Western blot analysis showed high levels of the human mitochondrial transcription factor A (Tfam). Interestingly, we also detected an additional Tfam product, of approximately 22 kDa. This is the first case in which a qualitatively abnormal Tfam has been found to be associated with a mitochondrial disorder in humans. ( info)

9/61. Mitochondrial gene defect in patients with chronic progressive external ophthalmoplegia.

    OBJECTIVE: To detect the gene defect of mitochondrial dna (mtDNA) from skeletal muscles in 2 patients with chronic progressive external ophthalmoplegia (CPEO). methods: After extraction of mtDNA, Southern hybridization was performed after restrictive digestion by Pvu II, EcoRI, Hind III, and Sacl. Then, we carried out polymerase chain reaction (PCR) and the enzyme digestion of the PCR products. Finally, mtDNA sequencing was done by automatic dna sequence analyzer. RESULTS: In case 1, a 5 kb deletion was found by Southern blot analysis and PCR. And dosage analysis showed a heteroplasmic change with 44% mtDNAs deleted. In case 2, PCR plus restriction endonuclease Pvu II digestion demonstrated a mutation which was confirmed by dna sequencing to be a single base substitution (T-->C) inducing a novel Pvu II site around 10,909 on mtDNA sequence. The laser image analyzer measurement revealed the mutation was almost homologous (99.4% mutant). CONCLUSIONS: In case 1, a 5 kb deletion found in mtDNA is called "common deletion" according to the literature. In case 2, a novel Pvu II site was found. It seems to be a de novo point mutation affecting ND4 in published CPEO research and is first reported in Chinese population. This point mutation does not induce an amino acid(Phe) change according to the published human mitochondrial genetic code as well as the mtDNA sequence. Whether it affects the translation efficiency or transportation of signals between mitochondrial and nuclear genome needs further studies. ( info)

10/61. A new mtDNA mutation in the tRNA(Leu(UUR)) gene associated with ocular myopathy.

    We studied a patient with ptosis, ophthalmoparesis, and exercise intolerance who showed in her muscle biopsy ragged-red fibers and combined defects of the complexes I and IV of the mitochondrial respiratory chain. Molecular analysis revealed a T3273C transition in the mitochondrial dna tRNA(Leu(UUR)) gene. The mutation was heteroplasmic and very abundant in muscle from the proposita, less abundant in her other tissues studied, and still less abundant in blood from her maternal relatives. Single muscle fiber analysis showed significantly higher levels of mutant genomes in ragged-red fibers than in normal fibers. The T3273C mutation affects a strictly conserved base pair in the anticodon stem and was not found in controls, thus satisfying the accepted criteria for pathogenicity. ( info)
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