title: Systematic review of autosomal recessive ataxias and proposal for a classification.
abstract: BACKGROUND
  The classification of autosomal recessive ataxias represents a significant challenge because of high genetic heterogeneity and complex phenotypes. We conducted a comprehensive systematic review of the literature to examine all recessive ataxias in order to propose a new classification and properly circumscribe this field as new technologies are emerging for comprehensive targeted gene testing.
  
  
  METHODS
  We searched Pubmed and Embase to identify original articles on recessive forms of ataxia in humans for which a causative gene had been identified. Reference lists and public databases, including OMIM and GeneReviews, were also reviewed. We evaluated the clinical descriptions to determine if ataxia was a core feature of the phenotype and assessed the available evidence on the genotype-phenotype association. Included disorders were classified as primary recessive ataxias, as other complex movement or multisystem disorders with prominent ataxia, or as disorders that may occasionally present with ataxia.
  
  
  RESULTS
  After removal of duplicates, 2354 references were reviewed and assessed for inclusion. A total of 130 articles were completely reviewed and included in this qualitative analysis. The proposed new list of autosomal recessive ataxias includes 45 gene-defined disorders for which ataxia is a core presenting feature. We propose a clinical algorithm based on the associated symptoms.
  
  
  CONCLUSIONS
  We present a new classification for autosomal recessive ataxias that brings awareness to their complex phenotypes while providing a unified categorization of this group of disorders. This review should assist in the development of a consensus nomenclature useful in both clinical and research applications.
authors.affiliation: Faculty of Medicine, Université Laval, Quebec city, QC G1V 0A6 Canada.
authors.forename: Marie
authors.initials: M
authors.lastname: Beaudin
authors.affiliation: Department of Neurology, Mayo Clinic, Rochester, MN 55905 USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Klein
authors.affiliation: Department of Neurology and Neurosurgery, McGill University, Montreal, QC H3A 1A4 Canada.
authors.forename: Guy A
authors.initials: GA
authors.lastname: Rouleau
authors.affiliation: Faculty of Medicine, Université Laval, Quebec city, QC G1V 0A6 Canada.|Department of Neurological Sciences, CHU de Quebec - Université Laval, 1401 18th street, Québec City, QC G1J 1Z4 Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Dupré
keywords: Cerebellar ataxia; Classification; Genetics; Recessive; Spinocerebellar degenerations