Gaucher disease (GD) is a lysosomal storage disorder caused by biallelic GBA1 variants. Epilepsy is uncommon in GD and rarely manifests as progressive myoclonus epilepsy (PME), making early recognition difficult. We describe a 20-year-old man with childhood-onset myoclonus that progressed to drug-resistant generalized seizures and cognitive decline. Video-electroencephalography (VEEG) showed generalized polyspike-wave discharges associated with myoclonic jerks, whereas brain magnetic resonance imaging was initially normal. Cerebrospinal fluid studies, metabolic screening, and autoimmune encephalitis antibody panels were unremarkable. Glucocerebrosidase activity was markedly reduced, and a targeted myoclonic-epilepsy gene panel identified two GBA1 variants: c.907C > A (p. Leu303Ile) and c.1505G > A (p. Arg502His), indicating a presumed compound-heterozygous state consistent with neuronopathic GD type 3. No hepatosplenomegaly or skeletal abnormalities were detected. Seizure control remained poor despite multiple antiseizure medications and vagus nerve stimulation (VNS). To contextualize this case, we systematically reviewed 22 publications encompassing 71 GD3-PME patients. Most cases presented in childhood, frequently showed typical electrophysiological patterns of generalized or multifocal polyspike-wave discharges, and had early normal MRI followed by later cerebellar or brainstem atrophy. Recurrent compound-heterozygous GBA1 variants, markedly reduced enzyme activity, and poor therapeutic response were common findings. The accompanying systematic review highlights the heterogeneity and therapeutic limitations of GD3-associated PME and underscores the importance of incorporating metabolic and genetic testing into the evaluation of unexplained PME for timely diagnosis and tailored management.

Neuronal Ceroid Lipofuscinoses type 7 (CLN7) is a paediatric lysosomal storage disease caused by mutations of the MFSD8 gene. Affected children have normal early development, but then suffer from progressive cognitive, motor, verbal, and visual decline. Ataxia and myoclonic epilepsy are predominant features of the condition, and there are no effective therapies. Death usually occurs by approximately age 11 years. While adeno-associated virus serotype 9 (AAV9) based gene therapy holds promise for treating monogenetic neurologic disorders, the impact of this intervention is limited by the maximum safe tolerable dose and the host immune response to the capsid and gene product. This study sought to confirm the safety of high dose intrathecal AAV-based gene therapy under a comprehensive immunosuppression regimen. This was a two-year open label, dose escalation, phase 1 first-in-human study of AAV9-based intrathecal gene therapy for CLN7. 4 participants (1 low dose, 3 high dose) were followed at regular intervals with blood work, CSF analysis, EEG, MRI, and measures of neurologic and neuropsychological function. This study provided evidence of safety for high dose intrathecal AAV9 based gene therapy in CLN7 disease under a specific immunosuppression regimen. Additionally, this study provides preliminary evidence of efficacy for this gene therapy. High dose intrathecal AAV based gene therapy can be pursued with adequate immunosuppression and monitoring for immune responses to the gene product. Additional long-term monitoring of the immune system during tapering of immunosuppression is needed to identify potential reactions to the gene product. This study was funded by The Batten's Hope Foundation, Mila's Miracle Foundation, Children's Health Dallas and Philanthropic Gifts to UT Southwestern. In addition, Emily R. Nettesheim received funding from NIH training grant 5T32GM131945-03 and Hamza Dahshi was supported in part by NIH award T32 GM152319.

Several genetic diseases affecting the human nervous system are incurable and insufficiently understood. Among them, nine rare diseases form the polyglutamine (polyQ) family: Huntington's disease (HD), spinocerebellar ataxia types 1, 2, 3, 6, 7, and 17, dentatorubral pallidoluysian atrophy, and spinal and bulbar muscular atrophy. In most patients, these diseases progress over decades to cause severe movement incoordination and neurodegeneration. Although their inherited genes with tandem-repeat elongations and the encoded polyQ-containing proteins have been extensively studied, the neuronal-type-specific pathologies and their long pre-symptomatic latency await further investigations. However, recent advances in detecting the single-nucleus transcriptome, alongside the length of tandem repeats in HD post-mortem brains, have enabled the identification of very high CAG repeat sizes that trigger transcriptional dysregulation and cell death in specific projection neurons. One challenge is to better understand the complexity of movement coordination circuits, including the basal ganglia and cerebellum neurons, which are most vulnerable to the high CAG expansion in each disease. Another challenge is to detect dynamic changes in CAG repeat length and their effects in vulnerable neurons at single-cell resolution. This will offer a platform for identifying pathological events in vulnerable long projection neurons and developing targeted therapies for all tandem-repeat expansions affecting the CNS projection neurons.

Neuronal ceroid lipofuscinosis (NCL) is a heterogeneous group of lysosomal disorders characterized by progressive psychomotor regression, visual impairment, and intractable seizures. Genetically, NCL type 3 (CLN3) is associated with variants in the gene encoding a lysosomal transmembrane protein. To date, few Japanese patients with CLN3 have been reported. Thus, their neurodevelopmental and clinical features remain unclear. Here, we report the clinical course of a genetically confirmed Japanese patient with CLN3. A 17-year-old Japanese boy was diagnosed with retinitis pigmentosa at age 7. Visual impairment progressed over a 10-year follow-up period. Generalized tonic-clonic seizures also began at age 7. Developmental regression was recognized at age 13, with an accelerated decline in motor and communication skills following a COVID-19 infection at age 17. Tube feeding and gastrostomy were initiated for dysphagia and recurrent respiratory infections. Serial MRI revealed progressive cerebral and cerebellar atrophy. Lymphopenia (351-1467/μL) was present from age 9; peripheral blood smear revealed vacuolated lymphocytes. Exome sequencing identified a heterozygous CLN3 variant, NM_001042432.2:c.295-2A > C. SpliceAI suggested exon 6 skipping and/or an 80-bp deletion, leading to nonsense-mediated mRNA decay. Manual inspection using Integrated Genomic Viewer revealed a second variant (c.178_180delinsACATCCTTAGCCACAAGAG) missed initially. Trio Sanger sequencing confirmed compound heterozygosity: NM_001042432.2:c.[295-2A > C]; [178_180delinsACATCCTTAGCCACAAGAG] p.[?]; [His60Thrfs∗10]. A review of 430 genetically confirmed CLN3 patients (1989-2025) identified no hematologic abnormalities. This Japanese CLN3 patient developed visual impairment 7-8 years before systemic deterioration. Retinal degeneration, together with vacuolated peripheral lymphocytes, may provide early diagnostic clues for CLN3 in Japanese patients.

Dentatorubral-pallidoluysian atrophy (DRPLA) is a neurodegenerative disorder that presents with ataxia, dementia and epilepsy. As a member of the polyglutamine family of diseases, DRPLA is caused by abnormal CAG triplet expansion beyond 48 repeats in the protein-coding region of ATROPHIN 1 (ATN1), a transcriptional co-repressor. To better understand DRPLA, we generated new Drosophila lines that can be induced to express full-length, human ATN1 with a normal (Q7) or pathogenic (Q88) repeat in a variety of cells, including neuronal, glial or any other type of tissue. Expression of ATN1 is toxic, with the polyglutamine-expanded version being consistently more problematic than wild-type ATN1. Fly motility, longevity and internal structures are negatively impacted by pathogenic ATN1. RNA-seq identified altered protein quality control and immune pathways in the presence of pathogenic ATN1. Based on these data, we conducted genetic experiments that confirmed the role of protein quality control components that ameliorate or exacerbate ATN1 toxicity. Hsc70-3, a chaperone, arose as a likely suppressor of toxicity. VCP (a proteasome-related AAA ATPase), Rpn11 (a proteasome-related deubiquitinase) and select DnaJ proteins (co-chaperones) were inconsistently protective, depending on the tissues where they were expressed. Lastly, informed by RNA-seq data that exercise-related genes may also be involved in this model of DRPLA, we conducted short-term exercise, which improved overall fly motility. This new model of DRPLA will prove important to understanding this understudied disease and will help to identify therapeutic targets for it.