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.
Mutations in Proline-rich Transmembrane Protein 2 (PRRT2) have been primarily associated with individuals presenting with infantile epilepsy, including benign familial infantile epilepsy, benign infantile epilepsy, and benign myoclonus of early infancy, and/or with dyskinetic paroxysms such as paroxysmal kinesigenic dyskinesia, paroxysmal non-kinesigenic dyskinesia, and exercise-induced dyskinesia.
A focal motor seizure phenomenologically manifested as a defined movement disorder in 29% of the patients from a consecutive video-EEG documented cohort as per consensus among experts: myoclonus and dystonia (10 and 9 cases, respectively) were the most common movement disorders, followed by chorea (4), stereotypies (3) myoclonus-dystonia (2), and tremor (1).
We identified three new de novo missense variants in KCNC1 in five unrelated individuals causing different phenotypes featuring either isolated nonprogressive myoclonus (p.Cys208Tyr), intellectual disability (p.Thr399Met), or epilepsy with myoclonic, absence and generalized tonic-clonic seizures, ataxia, and developmental delay (p.Ala421Val, three patients).
Here we present five subjects from three novel SCA21 families from different parts of the world (including a novel c.196G > A, p.G66RTMEM240 variant from Colombia), demonstrating that, in addition to cerebellar ataxia, not only hypokinetic features (hypomimia, bradykinesia), but also hyperkinetic movement disorders (poly-mini-myoclonus, proximal myoclonus) are a recurrent part of the phenotypic spectrum of SCA21.
To test the hypothesis that myoclonus in patients with multiple system atrophy with predominant cerebellar ataxia (MSA-C) is associated with a heavier burden of α-synuclein deposition in the motor regions of the spinal cord, we compared the degree of α-synuclein deposition in spinal cords of 3 patients with MSA-C with myoclonus and 3 without myoclonus.
Interestingly, GYS1<sup>Camk2a-KO</sup> animals did not show the greater susceptibility to hippocampal seizures and myoclonus observed in animals completely depleted of glycogen in the whole CNS.
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.
Moreover, heterozygous de novo frame-shift mutations in the C-terminal domain of KIF5A are associated with neonatal intractable myoclonus, a neurodevelopmental syndrome.
A recurrent p.Arg320His mutation in KCNC1 was identified in the two brothers who showed characteristic features of MEAK: near normal early development, onset of myoclonus around 10 years of age, infrequent generalized tonic-clonic seizures, relatively mild cognitive impairment, and generalized epileptiform discharges.
Phenotypic features not previously reported were seen; e.g. writer's cramp in SCA6; paroxysmal myoclonus in the glucose transporter protein type 1 (GLUT1) deficiency.
The adjunctive application of transcranial direct current stimulation in the management of de novo refractory epilepsia partialis continua in adolescent-onset POLG-related mitochondrial disease.
By contrast, dorsal forebrain-specific GLT1 knockout mice showed nonlethal complex seizures including myoclonic jerks, hyperkinetic running, spasm and clonic convulsion via the activation of NMDA receptors during a limited period from P12 to P14 and selective neuronal death in cortical layer II/III and the hippocampus.
Simultaneous video and EEG recordings revealed that Stxbp1+/- mice with different genomic backgrounds recapitulate the seizure/spasm phenotype observed in humans, characterized by myoclonic jerks and spike-wave discharges that were suppressed by the antiepileptic drug levetiracetam.
Additionally, the SNP of rs57095329 showed statistical significances with the appearances of mutism and the positive of cerebrospinal fluid (CSF) protein 14-3-3 in sCJD patients, while the SNP of ZBTB38-RASA2 was significantly related with the appearance of myoclonus in sCJD patients.
Additionally, the SNP of rs57095329 showed statistical significances with the appearances of mutism and the positive of cerebrospinal fluid (CSF) protein 14-3-3 in sCJD patients, while the SNP of ZBTB38-RASA2 was significantly related with the appearance of myoclonus in sCJD patients.