Leigh syndrome is a genetically heterogeneous disease caused by defects in enzymes involved in aerobic energy metabolism and the Krebs', cycle. Mitonchondrial complex I deficiency is a main cause of Leigh syndrome. In this study, a Chinese child with Leigh syndrome caused by 13513G>A mutation was reported. The proband was the first child of his parents. The previously healthy boy presented with generalized epilepsy at 12 years of age. When he visited Peking University First Hospital at 13 years of age, he had subacute loss of vision in two eyes and temporal defect of visual field in the left eye. He walked with a spastic gait. His blood lactate and pyruvate levels were elevated. Muscle biopsy showed mild lipid accumulation in muscle fiber. An electrocardiogram showed incomplete right bundle branch block. Brain magnetic resonance imaging showed bilateral, symmetrical lesions in the basal ganglia, supporting the diagnosis of Leigh syndrome. 13513G>A mutation was identified by gene analysis in the patient, which led to mitochondrial respiratory chain complex I deficiency. Multivitamins and L-carnitine were administered. At present, the patient is 16 years old and has progressive deterioration with significant muscle weakness and body weight loss. He is absent from school. He has no obvious retardation in intelligence. 13513G>A mutation was first identified by gene analysis in Chinese population with Leigh syndrome. This may be helpful in genetic counseling.
Adolescent ; DNA, Mitochondrial ; genetics ; Electron Transport Complex I ; deficiency ; Humans ; Leigh Disease ; genetics ; Male ; Mutation

Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome is a genetically heterogeneous mitochondrial disorder with variable clinical symptoms. Here, from the sequencing of the entire mitochondrial genome, we report a Korean MELAS family harboring two homoplasmic missense mutations, which were reported 9957T>C (Phe251Leu) transition mutation in the cytochrome c oxidase subunit 3 (COX3) gene and a novel 13849A>C (Asn505His) transversion mutation in the NADH dehydrogenase subunit 5 (ND5) gene. Neither of these mutations was found in 205 normal controls. Both mutations were identified from the proband and his mother, but not his father. The patients showed cataract symptom in addition to MELAS phenotype. We believe that the 9957T>C mutation is pathogenic, however, the 13849A>C mutation is of unclear significance. It is likely that the 13849A>C mutation might function as the secondary mutation which increase the expressivity of overlapping phenotypes of MELAS and cataract. This study also demonstrates the importance of full sequencing of mtDNA for the molecular genetic understanding of mitochondrial disorders.
Adult ; Asian Continental Ancestry Group ; DNA Mutational Analysis ; DNA, Mitochondrial/analysis/*genetics ; Electron Transport Complex I/*genetics ; Electron Transport Complex IV/*genetics ; Female ; Humans ; Korea ; MELAS Syndrome/*genetics ; Male ; Middle Aged ; Mitochondrial Proteins/*genetics ; *Mutation, Missense ; Pedigree ; Polymorphism, Genetic

This study reviews a case of mitochondrial respiratory chain complex I deficiency due to the 10191T>C mutation in mitochondrial ND3 gene. The previously healthy boy progressively presented with blepharoptosis, weakness, epilepsy and motor regression at age 6 years. Elevated blood lactate and pyruvate were observed. Brain magnetic resonance imaging showed symmetrical lesions in the basal ganglia. Leigh syndrome was thus confirmed. The protein from the mitochondria and genomic DNA of the boy and his parents was collected from peripheral blood leucocytes for the activity test for mitochondrial complex I to V and genetic analysis. The results showed the activity of complex I (33.1 nmol /min in 1 milligram mitochondrial protein) was lower than normal reference value (44.0±5.4 nmol /min in 1 milligram mitochondrial protein). The ratio of complex I to citrate synthase (19.8%) was also lower than normal reference value (48%±11%). The activities of complexes II to V were normal. 10191T>C mutation in ND3 gene of mitochondria was identified in the boy. 10191T>C mutation and complex I deficiency were not detected in his parents. At present, he is 16 years old, and of normal intelligence with spastic paralysis in both lower extremities after treatment. It is concluded that a Chinese boy with isolated complex I deficiency due to 10191T>C mutation in ND3 gene was firstly diagnosed by peripheral leukocytes mitochondrial respiratory chain enzyme assay and gene analysis. This study can provide clinical data for the nosogenesis of Leigh syndrome.
Adolescent ; Brain ; pathology ; Electron Transport Complex I ; deficiency ; genetics ; Humans ; Leigh Disease ; genetics ; Magnetic Resonance Imaging ; Male ; Mitochondrial Diseases ; genetics ; Mutation

OBJECTIVETo report a Chinese Han family with two patients of Leigh syndrome (LS) and to scan the mutation in mitochondrial DNA(mtDNA).

METHODSThe clinical features and the laboratory findings were summarized. Mitochondrial DNA chip and direct sequencing were performed to detect the mutation in entire mtDNA.

RESULTSFailure of thrive, psychomotor retardation, hypotonia and weakness, cerebellar ataxia, and seizure were the main manifestations of the family. Brain magnetic resonance imaging (MRI) showed lesions at midbrain, periaqueductal gray matter, dentate nuclei of cerebellar and thalami. The levels of lactic acid and pyruvate were mildly abnormal. The mutation of ND5*13513 G to A was identified in the LS family.

CONCLUSIONPatients with ND5*13513 G to A mutation may have a characteristic clinical course and ND5 *13513 G to A might be a preferential candidate mutation of Leigh syndrome.

Base Sequence ; Child, Preschool ; DNA, Mitochondrial ; genetics ; Electron Transport Complex I ; genetics ; Female ; Humans ; Infant ; Leigh Disease ; diagnostic imaging ; genetics ; pathology ; physiopathology ; Magnetic Resonance Imaging ; Male ; Mitochondrial Proteins ; genetics ; Polymorphism, Single Nucleotide ; genetics ; Tomography, X-Ray Computed

Both genetic and environmental factors are involved in the pathogenesis of Parkinsonos disease (PD). Epidemiological studies showed that environmental factors shared with the common mechanisms of resulting in alpha-synuclein aggregation by inhibiting complex I of mitochondria and leading to oxidative stress. To investigate the relationship between alpha-synuclein and oxidative stress, we used human dopaminergic SH-SY5Y cells transfected with alpha-synuclein-enhanced green fluorescent protein (EGFP). alpha-synuclein gene expression was determined by immunocytochemistry and real-time quantitative PCR. Both SH-SY5Y and alpha-synuclein overexpressed SH-SY5Y (SH-SY5Y/Syn) cells were treated with various concentrations of rotenone for different time. Cell viability and oxidative stress were detected by MTT assay and DCF assay. Superoxide dismutase (SOD) activity was assessed with xanthine peroxidase method. Cell apoptosis was detected with flow cytometry. Results showed that alpha-synuclein gene was constantly overexpressed in SH-SY5Y/Syn cells. After treatment with rotenone, both cell viability and complex I activity in these cells were reduced in a concentration-dependent manner. Oxidative stress was also found in these cells. Compared with SH-SY5Y cells, SOD activity in SH-SY5Y/Syn cells was increased distinctly (P<0.05) and alpha-synuclein significantly attenuated rotenone-induced cell apoptosis. These results suggest that the alpha-synuclein overexpression in SH-SY5Y cells has a tendency to partially resist oxidative stress induced by rotenone and this response may assist cell survival.
Apoptosis ; drug effects ; Cell Line ; Cell Survival ; drug effects ; Cytoprotection ; Dose-Response Relationship, Drug ; Electron Transport Complex I ; metabolism ; Humans ; Oxidative Stress ; Rotenone ; toxicity ; Superoxide Dismutase ; metabolism ; Superoxides ; metabolism ; alpha-Synuclein ; genetics ; physiology

OBJECTIVETo investigate variations of mtDNA in mouse tumors and to explore the relationship between mtDNA mutations and murine carcinogenesis.

METHODSVariations of D-loop, ND3 and tRNAIle + Glu + Met gene fragments of mtDNA from six mouse tumor cell lines were analyzed by PCR-RFLP and PCR-SSCP techniques.

RESULTSND3 and tRNAIle + Glu + Met gene fragments of mtDNA from the tumors showed no variations at 27 endonuclease sites. The D-loop of mtDNA from Hca-F demonstrated an additional endonuclease site of Hinf I in contrast to the inbred mouse. Upon PCR-SSCP analysis, the D-loop of mtDNA was found to possess mutations in 4 of 6 tumors.

CONCLUSIOND-loop appears to be the hot spot for tumor mtDNA mutations, which may contribute to the carcinogenesis of murine tumors.

Animals ; Cell Line, Tumor ; DNA, Mitochondrial ; genetics ; DNA, Neoplasm ; genetics ; Electron Transport Complex I ; Mice ; Mice, Inbred BALB C ; Mice, Inbred C3H ; Mice, Inbred C57BL ; Mutation ; Neoplasms, Experimental ; genetics ; pathology ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Polymorphism, Single-Stranded Conformational ; Proteins ; genetics ; RNA, Transfer, Glu ; genetics ; RNA, Transfer, Ile ; genetics ; RNA, Transfer, Met ; genetics