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

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

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.

Original languageEnglish (US)
JournalMovement Disorders
DOIs
StateAccepted/In press - Jan 1 2019

Fingerprint

Myoclonus
Advisory Committees
Terminology
Movement Disorders
Genes
Inborn Genetic Diseases
Phenotype
Myoclonic Epilepsy
Dystonia
Ataxia
Epilepsy

Keywords

  • genetics
  • hyperekplexia
  • myoclonic epilepsy
  • myoclonus
  • nomenclature

ASJC Scopus subject areas

  • Neurology
  • Clinical Neurology

Cite this

Nomenclature of Genetically Determined Myoclonus Syndromes : Recommendations of the International Parkinson and Movement Disorder Society Task Force. / van der Veen, Sterre; Zutt, Rodi; Klein, Christine; Marras, Connie; Berkovic, Samuel F.; Caviness, John N.; Shibasaki, Hiroshi; de Koning, Tom J.; Tijssen, Marina A.J.

In: Movement Disorders, 01.01.2019.

Research output: Contribution to journalReview article

van der Veen, Sterre ; Zutt, Rodi ; Klein, Christine ; Marras, Connie ; Berkovic, Samuel F. ; Caviness, John N. ; Shibasaki, Hiroshi ; de Koning, Tom J. ; Tijssen, Marina A.J. / Nomenclature of Genetically Determined Myoclonus Syndromes : Recommendations of the International Parkinson and Movement Disorder Society Task Force. In: Movement Disorders. 2019.
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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.",
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AU - Zutt, Rodi

AU - Klein, Christine

AU - Marras, Connie

AU - Berkovic, Samuel F.

AU - Caviness, John N.

AU - Shibasaki, Hiroshi

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