Myoclonus-dystonia (M-D) is an autosomal dominantly inherited movement disorder with myoclonic jerks and dystonic contractions most frequently due to a mutation in the epsilon-sarcoglycan (SGCE, DYT11) gene.
An 8-year-old boy presenting with early onset, medically intractable, MDS due to a mutation in the epsilon-sarcoglycan gene (SGCE) underwent chronic bilateral stimulation of the globus pallidus internus, which eliminates both myoclonus and dystonia.
The development of myoclonus in this patient lends further support to the hypothesis that abnormal imprinting of the SGCE gene is responsible for some cases of myoclonus-dystonia syndrome.
We report on the second M-D family in which several clinically affected epsilon-sarcoglycan gene (SGCE) mutation carriers have seizures in addition to myoclonus and dystonia, adding to the evidence that epilepsy and EEG abnormalities may form part of the phenotypic spectrum of the condition.
Patients with myoclonus and SGCE mutations also showed an improvement in action myoclonus (95%-100%) and in functional tests (50%-75%) according to the Unified Motor-Rating Scale.
Myoclonus-dystonia syndrome (MDS; DYT11) is an autosomal dominant disorder characterized by bilateral, alcohol-sensitive myoclonic jerks involving mainly the arms and axial muscles.
DYT11 myoclonus-dystonia (M-D) syndrome is a neurological movement disorder characterized by myoclonic jerks and dystonic postures or movement that can be alleviated by alcohol.
All of these factors may be genetically determined, but the greater hyperexcitability underlying more severe seizures and myoclonus at onset may also play a role by increasing cell damage due to reduced cystatin B activity.
Linkage analyses have shown that the genes for both these forms of myoclonus are closely linked to 21q22.3 DNA markers, suggesting that they are caused by mutations at the same locus (EPM1).
The aim of this article is to report on an early-onset AD patient associated with the rare pathogenic variant PSEN1 (Leu85Pro) presenting as a possible corticobasal syndrome with asymmetric limb apraxia, parkinsonian signs, and myoclonus.
Even though the vast majority of patients with EPM1 have a uniform genetic mutation, the actual size of the longer CSTB expansion mutation allele is likely to have a modulating effect on the age at disease onset, myoclonus severity, and cortical neurophysiology.
Presenilin 1 (PSEN1) gene mutations deterministic for Alzheimer's disease (AD) are associated with marked heterogeneity in clinical phenotype, with behavioral and psychiatric features, parkinsonism, myoclonus, epileptic seizures, spastic paraparesis, frontal behavioral changes suggestive of the phenotype of frontotemporal dementia, aphasia, and cerebellar ataxia being described as well as cognitive decline.