title: Clinical, biochemical, molecular, and histological features of 65 Portuguese patients with mitochondrial disorders.
abstract: BACKGROUND
  Mitochondrial disorders display remarkable genetic and phenotypic heterogeneity.
  
  
  METHODS
  We performed a retrospective analysis of the clinical, histological, biochemical, and genetic features of 65 patients with molecular diagnoses of mitochondrial disorders.
  
  
  RESULTS
  The most common genetic diagnosis was a single large-scale mitochondrial DNA (mtDNA) deletion (41.5%), and the most frequent clinical phenotype was chronic progressive external ophthalmoplegia (CPEO). It occurred in 41.5% of all patients, primarily in those with mtDNA deletions. Histological signs of mitochondrial dysfunction were found in 73.8% of patients, and respiratory chain enzyme assay (RCEA) abnormalities were detected in 51.9%.
  
  
  CONCLUSIONS
  This study confirms the high relative frequency of single large-scale deletions among mitochondrial disorders as well as its particular association with CPEO. Muscle histology seems to be particularly useful in older patients and those with mtDNA deletions, whereas RCEA might be more helpful in young children or individuals with mtDNA depletion. Muscle Nerve 56: 868-872, 2017.
authors.affiliation: Neurology Department, Hospital Prof. Doutor Fernando Fonseca, IC 19, 2720-276, Amadora, Portugal.
authors.forename: Simão
authors.initials: S
authors.lastname: Cruz
authors.affiliation: Neuropathology Unit, Hospital Santo António / Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Taipa
authors.affiliation: Newborn screening, Metabolism and Genetics Unit, Human Genetics Department, Dr. Ricardo Jorge National Health Institute, Porto, Portugal.
authors.forename: Célia
authors.initials: C
authors.lastname: Nogueira
authors.affiliation: Newborn screening, Metabolism and Genetics Unit, Human Genetics Department, Dr. Ricardo Jorge National Health Institute, Porto, Portugal.
authors.forename: Cristina
authors.initials: C
authors.lastname: Pereira
authors.affiliation: Newborn screening, Metabolism and Genetics Unit, Human Genetics Department, Dr. Ricardo Jorge National Health Institute, Porto, Portugal.
authors.forename: Lígia S
authors.initials: LS
authors.lastname: Almeida
authors.affiliation: Newborn screening, Metabolism and Genetics Unit, Human Genetics Department, Dr. Ricardo Jorge National Health Institute, Porto, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Neiva
authors.affiliation: Neurology Department, Hospital Garcia de Orta, Almada, Portugal.
authors.forename: Tiago
authors.initials: T
authors.lastname: Geraldes
authors.affiliation: Neuropathology Unit, Hospital Santo António / Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: António
authors.initials: A
authors.lastname: Guimarães
authors.affiliation: Neuropathology Unit, Hospital Santo António / Centro Hospitalar do Porto, Porto, Portugal.
authors.forename: Manuel
authors.initials: M
authors.lastname: Melo-Pires
authors.affiliation: Newborn screening, Metabolism and Genetics Unit, Human Genetics Department, Dr. Ricardo Jorge National Health Institute, Porto, Portugal.
authors.forename: Laura
authors.initials: L
authors.lastname: Vilarinho
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D028361:Mitochondrial Diseases / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009097:Multienzyme Complexes / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000473:pathology*; D017246:Ophthalmoplegia, Chronic Progressive External / Q000235:genetics; D011174:Portugal; D017384:Sequence Deletion / Q000235:genetics*; D055815:Young Adult
chemical_list: D004272:DNA, Mitochondrial; D009097:Multienzyme Complexes
keywords: chronic progressive external ophthalmoplegia; mitochondrial disorders; muscle biopsy; ragged red fibers; respiratory chain