Neurophysiological and BOLD signal uncoupling of giant somatosensory evoked potentials in progressive myoclonic epilepsy: a case-series study.

In progressive myoclonic epilepsy (PME), a rare epileptic syndrome caused by a variety of genetic disorders, the combination of peripheral stimulation and functional magnetic resonance imaging (fMRI) can shed light on the mechanisms underlying cortical dysfunction. The aim of the study is to investigate sensorimotor network modifications in PME by assessing the relationship between neurophysiological findings and blood oxygen level dependent (BOLD) activation. Somatosensory-evoked potential (SSEP) obtained briefly before fMRI and BOLD activation during median-nerve electrical stimulation were recorded in four subjects with typical PME phenotype and compared with normative data. Giant scalp SSEPs with enlarger N20-P25 complex compared to normal data (mean amplitude of 26.2 ± 8.2 µV after right stimulation and 27.9 ± 3.7 µV after left stimulation) were detected. Statistical group analysis showed a reduced BOLD activation in response to median nerve stimulation in PMEs compared to controls over the sensorimotor (SM) areas and an increased response over subcortical regions (p < 0.01, Z > 2.3, corrected). PMEs show dissociation between neurophysiological and BOLD findings of SSEPs (giant SSEP with reduced BOLD activation over SM). A direct pathway connecting a highly restricted area of the somatosensory cortex with the thalamus can be hypothesized to support the higher excitability of these areas.

Whole-transcriptome sequencing in blood provides a diagnosis of spinal muscular atrophy with progressive myoclonic epilepsy.

At least 15% of the disease-causing mutations affect mRNA splicing. Many splicing mutations are missed in a clinical setting due to limitations of in silico prediction algorithms or their location in noncoding regions. Whole-transcriptome sequencing is a promising new tool to identify these mutations; however, it will be a challenge to obtain disease-relevant tissue for RNA. Here, we describe an individual with a sporadic atypical spinal muscular atrophy, in whom clinical DNA sequencing reported one pathogenic ASAH1 mutation (c.458A>G;p.Tyr153Cys). Transcriptome sequencing on patient leukocytes identified a highly significant and atypical ASAH1 isoform not explained by c.458A>G(p<10-16 ). Subsequent Sanger-sequencing identified the splice mutation responsible for the isoform (c.504A>C;p.Lys168Asn) and provided a molecular diagnosis of autosomal-recessive spinal muscular atrophy with progressive myoclonic epilepsy. Our findings demonstrate the utility of RNA sequencing from blood to identify splice-impacting disease mutations for nonhematological conditions, providing a diagnosis for these otherwise unsolved patients.

GSTA1, GSTM1, GSTP1 and GSTT1 polymorphisms in progressive myoclonus epilepsy: A Serbian case-control study.

PURPOSE: Oxidative stress is recognized as an important factor in progressive myoclonus epilepsy (PME). Genetic polymorphism of glutathione S-transferases (GSTs), which are involved in both protection from oxidative damage and detoxification, might alter the capacity for protecting tissues from exogenous and endogenous oxidants. We aimed to assess a possible association between GST polymorphism and PME, as well as, correlation between GST genotypes and oxidative phenotype in PME patients. METHODS: GSTA1, GSTM1, GSTP1 and GSTT1 genotypes were determined in 26 patients with PME and 66 controls. Byproducts of protein oxidative damage (thiol groups (P-SH) and nitrotyrosine), superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities were determined. RESULTS: The frequency of GSTA1, GSTM1 and GSTP1 genotypes was not significantly different between PME patients and controls, while individuals with GSTT1-null genotype were at 5.44-fold higher risk of PME than carriers of GSTT1-active genotype. Moreover, significant risk of PME was obtained in carriers of both GSTT1-null and GSTM1-null genotypes. Carriers of combined GSTA1- active and GSTT1-null genotype were at highest, 7.55-fold increased risk of PME. Byproducts of protein damage did not reach statistical significance, while SOD and GPX activities were significantly higher in PME patients then in controls. When stratified according to GST genotype, P-SH groups were significantly lower only in patients with GSTT1-null genotype in comparison to carriers of active genotype. Only SOD activity was increased in GSTT1-null when compared to corresponding active genotype. CONCLUSIONS: GSTT1-null genotype might be associated with the increased risk and enhanced susceptibility to oxidative stress in PME patients.

Early-onset progressive myoclonic epilepsy with dystonia mapping to 16pter-p13.3.

The authors present three patients from a consanguineous family afflicted with novel recessive myoclonic epilepsy characterized by very early onset and a steadily progressive course. The onset is in early infancy, and death occurs in the first decade. In addition to various types of myoclonic seizures, episodic phenomena such as dystonias, postictal enduring hemipareses, autonomic involvements, and periods of obtundation and lethargy were also observed. Developmental and neurological retardation, coupled with systemic infections, leads to a full deterioration. The authors designated the disease progressive myoclonic epilepsy with dystonia (PMED). A genome scan for the family and subsequent fine mapping localized the gene responsible for the disease to the most telomeric 6.73 mega base pairs at the p-terminus of chromosome 16, with a maximum multipoint logarithm-of-odds score of 7.83 and a maximum two-point score of 4.25. A candidate gene was analyzed for mutations in patients, but no mutation was found.

Reduced serotonin and 3-hydroxyanthranilic acid levels in serum of cystatin B-deficient mice, a model system for progressive myoclonus epilepsy.

PURPOSE: To evaluate the levels of tryptophan and its metabolites along serotonin (5-HT) and kynurenine (KYN) pathways in serum of progressive myoclonus epilepsy (EPM1) patients and cystatin B (CSTB)-deficient mice, a model system for EPM1. METHODS: Tryptophan and its metabolites along serotonin (5-HT) and KYN pathways were determined in serum of EPM1 patients and CSTB-deficient mice by reverse-phase high-pressure liquid chromatography (HPLC) with electrochemical detection. RESULTS: Reduced levels of 5-HT and KYN intermediate metabolite 3-hydroxyanthranilic acid were found in serum of CSTB-deficient mice. A similar trend was found in EPM1 patients. Although tryptophan concentration was reduced in serum of EPM1 patients, no such decrease was observed in CSTB-deficient mice. CONCLUSIONS: The present study demonstrates that tryptophan metabolism along 5-HT and KYN pathways are disrupted in EPM1. Further studies are needed to elucidate the role of KYN pathway in pathogenesis of EPM1.