title: Exercise intolerance and developmental delay associated with a novel mitochondrial ND5 mutation.
abstract: The aim of this study was to evaluate the contribution of mitochondrial DNA (mtDNA) mutations in oxidative phosphorylation (OXPHOS) deficiency. The complete mitochondrial genomes of 41 families with OXPHOS deficiency were screened for mutations. Mitochondrial functional analysis was then performed in primary and cybrid cells containing candidate mutations identified during the screening. A novel mitochondrial NADH dehydrogenase 5 (ND5) m.12955A > G mutation was identified in a patient with exercise intolerance and developmental delay. A biochemical analysis revealed deficiencies in the activity of complex I (NADH:quinone oxidoreductase) and IV (cytochrome c oxidase) of this patient. Defects in complexes I and IV were confirmed in transmitochondrial cybrid cells containing the m.12955A > G mutation, suggesting that this mutation impairs complex I assembly, resulting in reduced stability of complex IV. Further functional investigations revealed that mitochondria with the m.12955A > G mutation exhibited lower OXPHOS coupling respiration and adenosine triphosphate (ATP) generation. In addition, the cytotoxic effects, determined as reactive oxygen species (ROS) and lactate levels in the present study, increased in the cells carrying a higher m.12955A > G mutant load. In conclusion, we identified m.12955A > G as a mitochondrial disease-related mutation. Therefore, screening of m.12955A > G is advised for the diagnosis of patients with mitochondrial disease.
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Hezhi
authors.initials: H
authors.lastname: Fang
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Shi
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Xiyuan
authors.initials: X
authors.lastname: Li
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Dayan
authors.initials: D
authors.lastname: Sun
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Fengjie
authors.initials: F
authors.lastname: Li
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yupeng
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yao
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Shen
authors.affiliation: Department of Cellular and Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Bai
authors.affiliation: Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
authors.forename: Yanling
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life sciences, Wenzhou Medical University, Wenzhou 325035, Zhejiang, China.
authors.forename: Jianxin
authors.initials: J
authors.lastname: Lu
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D001921:Brain / Q000000981:diagnostic imaging; D002648:Child; D045222:Electron Transport Chain Complex Proteins / Q000378:metabolism; D042967:Electron Transport Complex I / Q000235:genetics* / Q000378:metabolism; D015444:Exercise; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008928:Mitochondria / Q000378:metabolism*; D028361:Mitochondrial Diseases / Q000175:diagnosis* / Q000235:genetics; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D020125:Mutation, Missense; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption; D010375:Pedigree; D011859:Radiography; D017382:Reactive Oxygen Species / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D045222:Electron Transport Chain Complex Proteins; D024101:Mitochondrial Proteins; D017382:Reactive Oxygen Species; D000255:Adenosine Triphosphate; C481838:MT-ND5 protein, human; D042967:Electron Transport Complex I