Article Text

Download PDFPDF
Too many numbers and complexity: time to update the classifications of neurogenetic disorders?
  1. Jean-Michel Vallat1,
  2. Cyril Goizet2,3,
  3. Laurent Magy1,
  4. Stéphane Mathis1,4
  1. 1Department of Neurology (National Reference Center “Neuropathies Périphériques Rares”), University Hospital Dupuytren, Limoges, France
  2. 2Department of Medical Genetics, University Hospital (CHU Pellegrin), Bordeaux, France
  3. 3MRGM Laboratory (EA4576), University of Bordeaux, Bordeaux, France
  4. 4Department of Neurology, University Hospital, Poitiers, France
  1. Correspondence to Professor Jean-Michel Vallat, Department of Neurology, Centre de référence “Neuropathies Périphériques Rares”, University Hospital, Limoges, 2 Avenue Martin Luther King, Limoges 87042, France; jean-michel.vallat{at}

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


Neurogenetic disorders represent a wide spectrum of diseases defined as “clinical diseases caused by a defect in one or more genes, which affects the differentiation and function of the neuroectoderm and its derivates”: they can be divided into type 1 (when they result from a malfunction of a gene expressed in the neuroectoderm) or type 2 (in which neurological manifestations are caused indirectly by an abnormal gene not expressed in the nervous system);1 most of them can be classified in the group of ‘rare diseases’. Neurology has benefited from the genetic advances over the last three decades, transforming our understanding of nervous system disorders. Although the first clinical descriptions of certain neurogenetic disorders were reported in the nineteenth century, the first gene discoveries date back to the 1980s; since then, many genes have been identified with mutations implicated in an increasing number of neurogenetic disorders. It has been estimated that brain disorders may represent 60–70% of the total genetic disorders in clinical child neurology.2 In 2013, the total number of entries for genetic diseases in the OMIM website was 21 565 ( This growth of discovered disease-causing gene mutations leads to difficulties in the classification of genetically heterogeneous hereditary diseases, especially in many neurogenetic disorders.


After informal discussions with many clinicians in different meetings, we came to the conclusion that classifications in most neurogenetic disorders (among which Charcot–Marie–Tooth (CMT) diseases, hereditary spastic paraplegias (SPG) or hereditary cerebellar ataxias (HCA)) are poorly understood by non-expert physicians who are in the front line of management of patients with these disorders. We, therefore, conducted a literature search on classifications of these disorders mainly focusing on the papers published in the last five years as molecular genetics has made considerable strides over this period. We came to the conclusion that no decisive advance …

View Full Text


  • Contributors SM and J-MV were responsible for medical literature analysis, with intellectual contribution from CG and LM. SM and J-MV drafted the article. All authors contributed to the conception and design of the paper, interpretation of data, critical revisions contributing to the intellectual content and approval of the final version of the manuscript.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data on the OMIM website at