DNM1 encephalopathy: A new disease of vesicle fission

Neurology. 2017 Jul 25;89(4):385-394. doi: 10.1212/WNL.0000000000004152. Epub 2017 Jun 30.

Abstract

Objective: To evaluate the phenotypic spectrum caused by mutations in dynamin 1 (DNM1), encoding the presynaptic protein DNM1, and to investigate possible genotype-phenotype correlations and predicted functional consequences based on structural modeling.

Methods: We reviewed phenotypic data of 21 patients (7 previously published) with DNM1 mutations. We compared mutation data to known functional data and undertook biomolecular modeling to assess the effect of the mutations on protein function.

Results: We identified 19 patients with de novo mutations in DNM1 and a sibling pair who had an inherited mutation from a mosaic parent. Seven patients (33.3%) carried the recurrent p.Arg237Trp mutation. A common phenotype emerged that included severe to profound intellectual disability and muscular hypotonia in all patients and an epilepsy characterized by infantile spasms in 16 of 21 patients, frequently evolving into Lennox-Gastaut syndrome. Two patients had profound global developmental delay without seizures. In addition, we describe a single patient with normal development before the onset of a catastrophic epilepsy, consistent with febrile infection-related epilepsy syndrome at 4 years. All mutations cluster within the GTPase or middle domains, and structural modeling and existing functional data suggest a dominant-negative effect on DMN1 function.

Conclusions: The phenotypic spectrum of DNM1-related encephalopathy is relatively homogeneous, in contrast to many other genetic epilepsies. Up to one-third of patients carry the recurrent p.Arg237Trp variant, which is now one of the most common recurrent variants in epileptic encephalopathies identified to date. Given the predicted dominant-negative mechanism of this mutation, this variant presents a prime target for therapeutic intervention.

MeSH terms

  • Adolescent
  • Brain Diseases / genetics*
  • Brain Diseases / metabolism*
  • Child
  • Child, Preschool
  • Cohort Studies
  • DNA Mutational Analysis
  • Dynamins
  • Female
  • GTP Phosphohydrolases / genetics*
  • GTP Phosphohydrolases / metabolism*
  • Homeodomain Proteins
  • Humans
  • Infant
  • Male
  • Microtubule-Associated Proteins / genetics*
  • Microtubule-Associated Proteins / metabolism*
  • Mitochondrial Proteins / genetics*
  • Mitochondrial Proteins / metabolism*
  • Models, Molecular
  • Mutation*
  • Phenotype
  • Short Stature Homeobox Protein
  • Siblings
  • Synaptic Vesicles / metabolism
  • Young Adult

Substances

  • Homeodomain Proteins
  • Microtubule-Associated Proteins
  • Mitochondrial Proteins
  • SHOX protein, human
  • Short Stature Homeobox Protein
  • GTP Phosphohydrolases
  • DNM1L protein, human
  • Dynamins