Nomenclature of Genetically Determined Myoclonus Syndromes: Recommendations of the International Parkinson and Movement Disorder Society Task Force

Research output: Contribution to journalReview article

Abstract

Genetically determined myoclonus disorders are a result of a large number of genes. They have wide clinical variation and no systematic nomenclature. With next-generation sequencing, genetic diagnostics require stringent criteria to associate genes and phenotype. To improve (future) classification and recognition of genetically determined movement disorders, the Movement Disorder Society Task Force for Nomenclature of Genetic Movement Disorders (2012) advocates and renews the naming system of locus symbols. Here, we propose a nomenclature for myoclonus syndromes and related disorders with myoclonic jerks (hyperekplexia and myoclonic epileptic encephalopathies) to guide clinicians in their diagnostic approach to patients with these disorders. Sixty-seven genes were included in the nomenclature. They were divided into 3 subgroups: prominent myoclonus syndromes, 35 genes; prominent myoclonus syndromes combined with another prominent movement disorder, 9 genes; disorders that present usually with other phenotypes but can manifest as a prominent myoclonus syndrome, 23 genes. An additional movement disorder is seen in nearly all myoclonus syndromes: ataxia (n = 41), ataxia and dystonia (n = 6), and dystonia (n = 5). However, no additional movement disorders were seen in related disorders. Cognitive decline and epilepsy are present in the vast majority. The anatomical origin of myoclonus is known in 64% of genetic disorders: cortical (n = 34), noncortical areas (n = 8), and both (n = 1). Cortical myoclonus is commonly seen in association with ataxia, and noncortical myoclonus is often seen with myoclonus-dystonia. This new nomenclature of myoclonus will guide diagnostic testing and phenotype classification.

Details

Authors
  • Sterre van der Veen
  • Rodi Zutt
  • Christine Klein
  • Connie Marras
  • Samuel F. Berkovic
  • John N. Caviness
  • Hiroshi Shibasaki
  • Tom J. de Koning
  • Marina A.J. Tijssen
External organisations
  • Haga Teaching Hospital
  • University of Toronto
  • University of Melbourne
  • Mayo Clinic Scottsdale-Phoenix, Arizona
  • Kyoto University
  • University of Lübeck
  • University Medical Center Groningen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Medical Genetics

Keywords

  • genetics, hyperekplexia, myoclonic epilepsy, myoclonus, nomenclature
Original languageEnglish
Pages (from-to)1602-1613
Number of pages12
JournalMovement Disorders
Volume34
Issue number11
Publication statusPublished - 2019 Nov 1
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes