title: Leigh Syndrome in Childhood: Neurologic Progression and Functional Outcome.
abstract: OBJECTIVE
  Few studies have analyzed the clinical course and functional outcome in Leigh syndrome (LS). The aim of this study was to determine the clinical, radiological, biochemical, and genetic features of patients with LS, and identify prognostic indicators of the disease progression and neurological outcome.
  
  
  METHODS
  Thirty-nine patients who had been diagnosed with LS at the Seoul National University Children's Hospital were included. Their medical records, neuroimaging findings, and histological/biochemical findings of skeletal muscle specimens were reviewed. Targeted sequencing of mitochondrial DNA was performed based on mitochondrial respiratory chain (MRC) enzyme defects.
  
  
  RESULTS
  Isolated complex I deficiency was the most frequently observed MRC defect (in 42% of 38 investigated patients). Mitochondrial DNA mutations were identified in 11 patients, of which 81.8% were MT-ND genes. The clinical outcome varied widely, from independent daily activity to severe disability. Poor functional outcomes and neurological deterioration were significantly associated with early onset (before an age of 1 year) and the presence of other lesions additional to basal ganglia involvement in the initial neuroimaging.
  
  
  CONCLUSIONS
  The neurological severity and outcome of LS may vary widely and be better than those predicted based on previous studies. We suggest that age at onset and initial neuroimaging findings are prognostic indicators in LS.
authors.affiliation: Department of Pediatrics, Gachon University Gil Medical Center, Incheon, Korea.
authors.forename: Jin Sook
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hunmin
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Pediatric Clinical Neuroscience Center, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Byung Chan
authors.initials: BC
authors.lastname: Lim
authors.affiliation: Department of Pediatrics, Seoul National University Bundang Hospital, Seongnam, Korea.
authors.forename: Hee
authors.initials: H
authors.lastname: Hwang
authors.affiliation: Department of Pediatrics, SMG-SNU Boramae Hospital, Seoul, Korea.
authors.forename: Jieun
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Pediatrics, Pediatric Clinical Neuroscience Center, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ki Joong
authors.initials: KJ
authors.lastname: Kim
authors.affiliation: Department of Pediatrics, Pediatric Clinical Neuroscience Center, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Yong Seung
authors.initials: YS
authors.lastname: Hwang
authors.affiliation: Department of Pediatrics, Pediatric Clinical Neuroscience Center, Seoul National University Children's Hospital, Seoul National University College of Medicine, Seoul, Korea. chaeped1@snu.ac.kr.
authors.forename: Jong Hee
authors.initials: JH
authors.lastname: Chae
keywords: Leigh syndrome; functional outcome; mitochondrial DNA mutation; prognostic indicators