title: Prevalence and phenotypes of congenital myopathy due to α-actin 1 gene mutations.
abstract: BACKGROUND
  Congenital myopathy due to mutations in the α-actin 1 gene (ACTA1) was identified in 1999, but knowledge of prevalence and phenotype in patients who survive 5 years is lacking.
  
  
  METHODS
  A national cohort of 91 patients aged ≥5 years and diagnosed with congenital myopathy was assessed for ACTA1 mutations and investigated clinically.
  
  
  RESULTS
  Four patients with ACTA1 mutations were identified, yielding a prevalence of 4.4%. Patients were 10-23 years of age, and all but 1 were ambulatory. Vital capacity ranged from 47% to 70% predicted, and 1 patient needed nocturnal bi-level positive airway pressure. Limb flexor/extensor muscles and upper and lower extremities were affected equally. Pronounced neck flexor weakness was noted.
  
  
  CONCLUSIONS
  Congenital myopathy caused by ACTA1 mutations is fatal in infancy in most cases. This study shows that the prevalence of α-actin myopathy in older patients with congenital myopathy is not negligible and that phenotypes can be quite mild.
authors.affiliation: Copenhagen Neuromuscular Center, Department of Neurology, 2081, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
authors.forename: Nanna
authors.initials: N
authors.lastname: Witting
authors.affiliation: Danish National Rehabilitation Center for Neuromuscular Diseases, Aarhus, Denmark.
authors.forename: Ulla
authors.initials: U
authors.lastname: Werlauff
authors.affiliation: Department of Clinical Genetics, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Morten
authors.initials: M
authors.lastname: Duno
authors.affiliation: Copenhagen Neuromuscular Center, Department of Neurology, 2081, Rigshospitalet, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
authors.forename: John
authors.initials: J
authors.lastname: Vissing
mesh_terms: D000199:Actins / Q000235:genetics*; D000293:Adolescent; D002648:Child; D003402:Creatine Kinase / Q000097:blood; D003718:Denmark; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009154:Mutation / Q000235:genetics*; D009224:Myotonia Congenita / Q000453:epidemiology* / Q000235:genetics* / Q000503:physiopathology; D010641:Phenotype; D015995:Prevalence; D055815:Young Adult
chemical_list: D000199:Actins; D003402:Creatine Kinase
keywords: ACTA1; congenital myopathy; nemaline myopathy; phenotype; prevalence