進行性ミオクローヌスてんかん

The extracellular milieu, including extracellular vesicles (EVs), plays a pivotal role in brain development. In this study, we sought to elucidate the pathogenesis of progressive myoclonus epilepsy type 1 (EPM1), a disease caused by mutations in the CSTB gene, using cerebral organoids (COs) derived from patient cells. The results demonstrate that EPM1 COs display increased electrophysiological activity and disrupted excitatory/inhibitory (E/I) balance. Single-cell RNA sequencing analysis of ventral EPM1-COs revealed an abnormal specification of progenitor fate, with a shift toward dorsal neuron identities. We demonstrated that this misspecification is driven by a functional alteration of the ventral signaling niche, resulting from impaired EV dynamics and altered protein cargo. Mechanistically, we identified Sonic Hedgehog (SHH) as a direct physical interactor of CSTB and demonstrated that CSTB deficiency leads to reduced SHH content and secretion. Our findings establish CSTB as a safeguard of ventral patterning and identify the CSTB-SHH-EV axis as a potential therapeutic target for mitigating the E/I imbalance associated with EPM1.

Acid ceramidase (aCDase) is a lysosomal amidase that catalyzes the hydrolysis of sphingolipids (SphL), including ceramides and glucosylceramides. Altered expressions of aCDase are associated with several pathological conditions, such as cancer, inflammation, pain, and pulmonary disorders. aCDase activity is reduced in Farber disease, spinal muscular atrophy with progressive myoclonic epilepsy, diabetes, and cardiovascular disease. Recent reports suggest that aCDase inhibition may be an emerging strategy for treating several SphL-related neurodegenerative conditions, such as Krabbe, Gaucher, and Parkinson's disease, due to its role in the accumulation of glycosphingolipids. Therefore, the development of a tissue-based aCDase activity assay has potential applications in clinical diagnostics and drug discovery, enabling the evaluation of the onset and progression of disease from biological samples of patients, drug-target engagement analysis, and identification of biomarkers. Here, we report a detailed protocol for detecting aCDase activity in tissue lysates, using Rbm14-12 as a specific fluorogenic substrate for aCDase. Assay protocol optimization, including a procedure for the preparation and storage of tissue lysates and the identification of optimal protein tissue lysate amounts and substrate concentrations based on kinetic enzymatic parameter analyses, is described. Key features • This protocol relies on the use of the Rbm14-12 fluorogenic substrate. • This protocol was developed out of a need to measure the target engagement of an aCDase-targeting therapeutic in a Parkinson's disease-related animal model. • This protocol can be broadly useful for sensitively measuring aCDase activity in central and peripheral organ tissues.

BACKGROUND: Variants in GBA1 are associated with neurodegenerative disease. This study aimed to explore pathogenic GBA1 variants. METHODS: Four patients with progressive myoclonic epilepsy (PME) and extremely low β-glucosidase levels were recruited. Whole-exome sequencing and long-range PCR were performed to identify GBA1 variants. Bioinformatic analyses were used to predict the impact of the identified variants. A literature review was performed to explore the genotype-phenotype correlations. GBA1 expression data across different brain regions and developmental stages were analyzed using the BrainSpan database. RT-PCR was performed to verify the splicing effects. RESULTS: Compound heterozygous GBA1 variants were identified in four patients. Five distinct variants were detected, including two novel splice site variants (c.308-2A>G and c.762-2A>C) and three previously reported variants. All identified variants were rare or absent in gnomAD. Splice site variants c.308-2A>G and c.762-2A>C were predicted to cause aberrant splicing. Minigene-based splicing assays coupled with RT-PCR and Sanger sequencing confirmed that both variants cause complete exon skipping (exon 4 and exon 7, respectively). All patients presented with PME onset in childhood/adolescence, intellectual regression, low β-glucosidase, and diffuse brain atrophy and were subsequently diagnosed with Gaucher disease type 3. GBA1 expression in the brain showed two distinct peaks: one in infancy and another after five years of age. The onset age of PME aligned with the second GBA1 expression peak (after five years of age). CONCLUSION: This study identified compound heterozygous GBA1 variants, including two novel candidate pathogenic splice site variants, in Gaucher disease type 3 patients, expanding the known mutational spectrum.

OBJECTIVES: Asparagine synthetase deficiency is a rare autosomal recessive neurometabolic disorder characterized by congenital and progressive microcephaly, severe developmental delay, epilepsy, and progressive cerebral atrophy. Therapeutic experience with L-asparagine supplementation remains limited and heterogeneous. CASE PRESENTATION: We report a preterm female infant born to consanguineous parents who presented with congenital microcephaly and early-onset myoclonic epilepsy. During follow-up, diaphragmatic eventration was identified and contributed to recurrent episodes of respiratory failure. Metabolic screening studies were unremarkable; however, cerebrospinal fluid asparagine concentration was markedly reduced (4.42 μmol/L; reference range 8-34 μmol/L). Brain magnetic resonance imaging demonstrated cerebral atrophy with white matter involvement. Whole-exome sequencing identified a homozygous splice-site variant in the ASNS gene. Oral L-asparagine supplementation was initiated at 5 months of age (50 mg/kg/day and increased to 100 mg/kg/day after one week). A reduction in seizure frequency was observed following treatment initiation; however, this finding should be interpreted cautiously because it coincided with changes in antiepileptic therapy. No meaningful neurodevelopmental progress was observed during follow-up. CONCLUSIONS: ASNSD should be suspected in patients with progressive microcephaly and early-onset epilepsy despite normal metabolic screening, and CSF amino acid analysis is valuable for diagnosis. Although a reduction in seizure frequency was observed following L-asparagine supplementation in our patient, this finding should be interpreted cautiously because phenobarbital was discontinued and topiramate therapy was initiated during the same period. Therefore, the therapeutic efficacy of L-asparagine supplementation remains uncertain, and its impact on neurodevelopment appears limited.