Lafora progressive myoclonus epilepsy: Disease mechanism and therapeutic attempts.

Lafora disease (LD) is a life-threatening autosomal recessive and progressive neurodegenerative disorder that primarily affects adolescents, resulting in mortality within a decade of onset. The symptoms of LD include epileptic seizures, ataxia, dementia, and psychosis. The underlying pathology involves the presence of abnormal glycogen inclusions in neurons and other tissues, which may contribute to neurodegeneration. LD is caused by loss-of-function mutations in either the EPM2A gene or the NHLRC1 gene. These two genes, respectively, code for laforin phosphatase and malin ubiquitin ligase, and are thought to function, as a functional complex, in diverse cellular pathways. One of the major pathways affected in LD is glycogen metabolism; defects here lead to abnormally higher levels of glycogen and its hyperphosphorylation and aggregation, resulting in the formation of Lafora inclusion bodies. Currently, there is no effective therapy for LD. Studies, particularly from animal models, provide distinct insights into the fundamental mechanisms of diseases and potential avenues for therapeutic interventions. The purpose of this review is to present a comprehensive overview of our current knowledge regarding the disease, its genetics, the animal models that have been developed, and the therapeutic strategies that are being developed based on an understanding of the disease mechanism.

AAV-Mediated Artificial miRNA Reduces Pathogenic Polyglucosan Bodies and Neuroinflammation in Adult Polyglucosan Body and Lafora Disease Mouse Models.

Adult polyglucosan body disease (APBD) and Lafora disease (LD) are autosomal recessive glycogen storage neurological disorders. APBD is caused by mutations in the glycogen branching enzyme (GBE1) gene and is characterized by progressive upper and lower motor neuron dysfunction and premature death. LD is a fatal progressive myoclonus epilepsy caused by loss of function mutations in the EPM2A or EPM2B gene. These clinically distinct neurogenetic diseases share a common pathology. This consists of time-dependent formation, precipitation, and accumulation of an abnormal form of glycogen (polyglucosan) into gradually enlarging inclusions, polyglucosan bodies (PBs) in ever-increasing numbers of neurons and astrocytes. The growth and spread of PBs are followed by astrogliosis, microgliosis, and neurodegeneration. The key defect in polyglucosans is that their glucan branches are longer than those of normal glycogen, which prevents them from remaining in solution. Since the lengths of glycogen branches are determined by the enzyme glycogen synthase, we hypothesized that downregulating this enzyme could prevent or hinder the generation of the pathogenic PBs. Here, we pursued an adeno-associated virus vector (AAV) mediated RNA-interference (RNAi) strategy. This approach resulted in approximately 15% reduction of glycogen synthase mRNA and an approximately 40% reduction of PBs across the brain in the APBD and both LD mouse models. This was accompanied by improvements in early neuroinflammatory markers of disease. This work represents proof of principle toward developing a single lifetime dose therapy for two fatal neurological diseases: APBD and LD. The approach is likely applicable to other severe and common diseases of glycogen storage.

Lafora disease: Current biology and therapeutic approaches.

The ubiquitin system impacts most cellular processes and is altered in numerous neurodegenerative diseases. However, little is known about its role in neurodegenerative diseases due to disturbances of glycogen metabolism such as Lafora disease (LD). In LD, insufficiently branched and long-chained glycogen forms and precipitates into insoluble polyglucosan bodies (Lafora bodies), which drive neuroinflammation, neurodegeneration and epilepsy. LD is caused by mutations in the gene encoding the glycogen phosphatase laforin or the gene coding for the laforin interacting partner ubiquitin E3 ligase malin. The role of the malin-laforin complex in regulating glycogen structure remains with full of gaps. In this review we bring together the disparate body of data on these two proteins and propose a mechanistic hypothesis of the disease in which malin-laforin's role to monitor and prevent over-elongation of glycogen branch chains, which drive glycogen molecules to precipitate and accumulate into Lafora bodies. We also review proposed connections between Lafora bodies and the ensuing neuroinflammation, neurodegeneration and intractable epilepsy. Finally, we review the exciting activities in developing therapies for Lafora disease based on replacing the missing genes, slowing the enzyme - glycogen synthase - that over-elongates glycogen branches, and introducing enzymes that can digest Lafora bodies. Much more work is needed to fill the gaps in glycogen metabolism in which laforin and malin operate. However, knowledge appears already adequate to advance disease course altering therapies for this catastrophic fatal disease.

A novel gene therapy for neurodegenerative Lafora disease via EPM2A-loaded DLinDMA lipoplexes.

Aim: To develop novel cationic liposomes as a nonviral gene delivery vector for the treatment of rare diseases, such as Lafora disease - a neurodegenerative epilepsy. Materials & methods: DLinDMA and DOTAP liposomes were formulated and characterized for the delivery of gene encoding laforin and expression of functional protein in HEK293 and neuroblastoma cells. Results: Liposomes with cationic lipids DLinDMA and DOTAP showed good physicochemical characteristics. Nanosized DLinDMA liposomes demonstrated desired transfection efficiency, negligible hemolysis and minimal cytotoxicity. Western blotting confirmed successful expression and glucan phosphatase assay demonstrated the biological activity of laforin. Conclusion: Our study is a novel preclinical effort in formulating cationic lipoplexes containing plasmid DNA for the therapy of rare genetic diseases such as Lafora disease.

Targeting Gys1 with AAV-SaCas9 Decreases Pathogenic Polyglucosan Bodies and Neuroinflammation in Adult Polyglucosan Body and Lafora Disease Mouse Models.

Many adult and most childhood neurological diseases have a genetic basis. CRISPR/Cas9 biotechnology holds great promise in neurological therapy, pending the clearance of major delivery, efficiency, and specificity hurdles. We applied CRISPR/Cas9 genome editing in its simplest modality, namely inducing gene sequence disruption, to one adult and one pediatric disease. Adult polyglucosan body disease is a neurodegenerative disease resembling amyotrophic lateral sclerosis. Lafora disease is a severe late childhood onset progressive myoclonus epilepsy. The pathogenic insult in both is formation in the brain of glycogen with overlong branches, which precipitates and accumulates into polyglucosan bodies that drive neuroinflammation and neurodegeneration. We packaged Staphylococcus aureus Cas9 and a guide RNA targeting the glycogen synthase gene, Gys1, responsible for brain glycogen branch elongation in AAV9 virus, which we delivered by neonatal intracerebroventricular injection to one mouse model of adult polyglucosan body disease and two mouse models of Lafora disease. This resulted, in all three models, in editing of approximately 17% of Gys1 alleles and a similar extent of reduction of Gys1 mRNA across the brain. The latter led to approximately 50% reductions of GYS1 protein, abnormal glycogen accumulation, and polyglucosan bodies, as well as ameliorations of neuroinflammatory markers in all three models. Our work represents proof of principle for virally delivered CRISPR/Cas9 neurotherapeutics in an adult-onset (adult polyglucosan body) and a childhood-onset (Lafora) neurological diseases.

The 5th International Lafora Epilepsy Workshop: Basic science elucidating therapeutic options and preparing for therapies in the clinic.

Lafora disease (LD) is both a fatal childhood epilepsy and a glycogen storage disease caused by recessive mutations in either the Epilepsy progressive myoclonus 2A (EPM2A) or EPM2B genes. Hallmarks of LD are aberrant, cytoplasmic carbohydrate aggregates called Lafora bodies (LBs) that are a disease driver. The 5th International Lafora Epilepsy Workshop was recently held in Alcala de Henares, Spain. The workshop brought together nearly 100 clinicians, academic and industry scientists, trainees, National Institutes of Health (NIH) representation, and friends and family members of patients with LD. The workshop covered aspects of LD ranging from defining basic scientific mechanisms to elucidating a LD therapy or cure and a recently launched LD natural history study.

Targeting Pathogenic Lafora Bodies in Lafora Disease Using an Antibody-Enzyme Fusion.

Lafora disease (LD) is a fatal childhood epilepsy caused by recessive mutations in either the EPM2A or EPM2B gene. A hallmark of LD is the intracellular accumulation of insoluble polysaccharide deposits known as Lafora bodies (LBs) in the brain and other tissues. In LD mouse models, genetic reduction of glycogen synthesis eliminates LB formation and rescues the neurological phenotype. Therefore, LBs have become a therapeutic target for ameliorating LD. Herein, we demonstrate that human pancreatic α-amylase degrades LBs. We fused this amylase to a cell-penetrating antibody fragment, and this antibody-enzyme fusion (VAL-0417) degrades LBs in vitro and dramatically reduces LB loads in vivo in Epm2a-/- mice. Using metabolomics and multivariate analysis, we demonstrate that VAL-0417 treatment of Epm2a-/- mice reverses the metabolic phenotype to a wild-type profile. VAL-0417 is a promising drug for the treatment of LD and a putative precision therapy platform for intractable epilepsy.

[Lafora disease: a review of the literature]. / Enfermedad de Lafora: revision de la bibliografia.

INTRODUCTION: Lafora disease is autosomal recessive progressive myoclonus epilepsy with late childhood-to teenage-onset caused by loss-of-function mutations in either EPM2A or EPM2B genes encoding laforin or malin, respectively. DEVELOPMENT: The main symptoms of Lafora disease, which worsen progressively, are: myoclonus, occipital seizures, generalized tonic-clonic seizures, cognitive decline, neuropsychiatric syptoms and ataxia with a fatal outcome. Pathologically, Lafora disease is characterized by the presence of polyglucosans deposits (named Lafora bodies), in the brain, liver, muscle and sweat glands. Diagnosis of Lafora disease is made through clinical, electrophysiological, histological and genetic findings. Currently, there is no treatment to cure or prevent the development of the disease. Traditionally, antiepileptic drugs are used for the management of myoclonus and seizures. However, patients become drug-resistant after the initial stage. CONCLUSIONS: Lafora disease is a rare pathology that has serious consequences for patients and their caregivers despite its low prevalence. Therefore, continuing research in order to clarify the underlying mechanisms and hopefully developing new palliative and curative treatments for the disease is necessary.

TITLE: Enfermedad de Lafora: revision de la bibliografia.Introduccion. La enfermedad de Lafora es una forma de epilepsia mioclonica progresiva de herencia autosomica recesiva, de inicio en la infancia tardia o en la adolescencia, y producida por mutaciones de perdida de funcion en los genes EPM2A o EPM2B, los cuales codifican para las proteinas laforina y malina, respectivamente. Desarrollo. Los principales sintomas de la enfermedad, que empeoran progresivamente, son mioclonias, crisis occipitales, crisis tonicoclonicas generalizadas, deterioro cognitivo, sintomas neuropsiquiatricos y ataxia. El curso es progresivo y fatal. Patologicamente, se caracteriza por la presencia de depositos de poliglucosanos (denominados cuerpos de Lafora) en el cerebro, el higado, el musculo y las glandulas sudoriparas. El diagnostico de enfermedad de Lafora se realiza mediante hallazgos clinicos, electrofisiologicos, histologicos y geneticos. En la actualidad no existe un tratamiento que erradique o prevenga su desarrollo. Tradicionalmente, se utilizan farmacos antiepilepticos para el tratamiento de las mioclonias y las convulsiones, aunque aparecen resistencias a estas. Conclusiones. La enfermedad de Lafora es una patologia rara que, pese a su baja prevalencia, supone graves consecuencias para los pacientes y sus cuidadores. Asi pues, resulta necesario continuar la investigacion para clarificar los mecanismos subyacentes y desarrollar nuevos tratamientos paliativos y curativos de la enfermedad.

Lafora Disease: A Review of Molecular Mechanisms and Pathology.

Lafora's disease is a neurodegenerative disorder caused by recessive loss-of-function mutations in the EPM2A (laforin glycogen phosphatase) or EPM2B (malin E3 ubiquitin ligase) genes. Neuropathology is characterized by malformed precipitated glycogen aggregates termed Lafora bodies. Asymptomatic until adolescence, patients undergo first insidious then rapid progressive myoclonus epilepsy toward a vegetative state and death within a decade. Laforin and malin interact to regulate glycogen phosphorylation and chain length pattern, the latter critical to glycogen's solubility. Significant gaps remain in precise mechanistic understanding. However, demonstration that partial reduction in brain glycogen synthesis near-completely prevents the disease in its genetic animal models opens a direct present path to therapy.

Lafora disease - from pathogenesis to treatment strategies.

Lafora disease is a severe, autosomal recessive, progressive myoclonus epilepsy. The disease usually manifests in previously healthy adolescents, and death commonly occurs within 10 years of symptom onset. Lafora disease is caused by loss-of-function mutations in EPM2A or NHLRC1, which encode laforin and malin, respectively. The absence of either protein results in poorly branched, hyperphosphorylated glycogen, which precipitates, aggregates and accumulates into Lafora bodies. Evidence from Lafora disease genetic mouse models indicates that these intracellular inclusions are a principal driver of neurodegeneration and neurological disease. The integration of current knowledge on the function of laforin-malin as an interacting complex suggests that laforin recruits malin to parts of glycogen molecules where overly long glucose chains are forming, so as to counteract further chain extension. In the absence of either laforin or malin function, long glucose chains in specific glycogen molecules extrude water, form double helices and drive precipitation of those molecules, which over time accumulate into Lafora bodies. In this article, we review the genetic, clinical, pathological and molecular aspects of Lafora disease. We also discuss traditional antiseizure treatments for this condition, as well as exciting therapeutic advances based on the downregulation of brain glycogen synthesis and disease gene replacement.

Lafora disease: from genotype to phenotype.

The progressive myoclonic epilepsy of Lafora or Lafora disease (LD) is a neurodegenerative disorder characterized by recurrent seizures and cognitive deficits. With typical onset in the late childhood or early adolescence, the patients show progressive worsening of the disease symptoms, leading to death in about 10 years. It is an autosomal recessive disorder caused by the loss-of-function mutations in the EPM2A gene, coding for a protein phosphatase (laforin) or the NHLRC1 gene coding for an E3 ubiquitin ligase (malin). LD is characterized by the presence of abnormally branched water insoluble glycogen inclusions known as Lafora bodies in the neurons and other tissues, suggesting a role for laforin and malin in glycogen metabolic pathways. Mouse models of LD, developed by targeted disruption of the Epm2a or Nhlrc1 gene, recapitulated most of the symptoms and pathological features as seen in humans, and have offered insight into the pathomechanisms. Besides the formation of Lafora bodies in the neurons in the presymptomatic stage, the animal models have also demonstrated perturbations in the proteolytic pathways, such as ubiquitin proteasome system and autophagy, and inflammatory response. This review attempts to provide a comprehensive coverage on the genetic defects leading to the LD in humans, on the functional properties of the laforin and malin proteins, and on how defects in any one of these two proteins result in a clinically similar phenotype. We also discuss the disease pathologies as revealed by the studies on the animal models and, finally, on the progress with therapeutic attempts albeit in the animal models.

Lafora disease offers a unique window into neuronal glycogen metabolism.

Lafora disease (LD) is a fatal, autosomal recessive, glycogen-storage disorder that manifests as severe epilepsy. LD results from mutations in the gene encoding either the glycogen phosphatase laforin or the E3 ubiquitin ligase malin. Individuals with LD develop cytoplasmic, aberrant glycogen inclusions in nearly all tissues that more closely resemble plant starch than human glycogen. This Minireview discusses the unique window into glycogen metabolism that LD research offers. It also highlights recent discoveries, including that glycogen contains covalently bound phosphate and that neurons synthesize glycogen and express both glycogen synthase and glycogen phosphorylase.

Managing Lafora body disease with vagal nerve stimulation.

A 17-year-old female, of consanguineous parents, presented with a history of seizures and cognitive decline since the age of 12 years. She had absence, focal dyscognitive, generalized myoclonic, and generalized tonic-clonic seizures, all of which were drug resistant. The diagnosis of Lafora body disease was made based on a compatible clinical, EEG, seizure semiology picture and a disease-causing homozygous mutation in the EPM2A gene. A vagus nerve stimulator (VNS) was inserted and well tolerated with a steady decrease and then stabilization in seizure frequency during the six months following insertion (months 1-6). At follow-up, at 12 months after VNS insertion, there was a persistent improvement. Seizure frequency during months 7-12, compared to pre-VNS, was documented as follows: the absence seizures observed by the family had decreased from four episodes per month to 0 per month, the focal dyscognitive seizures from 300 episodes per month to 90 per month, the generalized myoclonic seizures from 90 clusters per month to eight per month, and the generalized tonic-clonic seizures from 30 episodes per month to 1.5 per month on average. To our knowledge, this is the second case reported in the literature showing efficacy of VNS in the management of seizures in Lafora body disease.

Mild Lafora disease: clinical, neurophysiologic, and genetic findings.

We report clinical, neurophysiologic, and genetic features of an Italian series of patients with Lafora disease (LD) to identify distinguishing features of those with a slowly progressive course. Twenty-three patients with LD (17 female; 6 male) were recruited. Mean age (± SD) at the disease onset was 14.5 ± 3.9 years and mean follow-up duration was 13.2 ± 8.0 years. NHLRC1 mutations were detected in 18 patients; EPM2A mutations were identified in 5. Patients who maintained >10 years gait autonomy were labeled as "mild" and were compared with the remaining LD patients with a typical course. Six of 23 patients were mild and presented significantly delay in the age at onset, lower neurologic disability score at 4 years after the onset, less severe seizure phenotype, lower probability of showing both photoparoxysmal response on electroencephalography (EEG) and giant somatosensory evoked potentials, as compared to patients with typical LD. However, in both mild and typical LD patients, EEG showed disorganization of background activity and frequent epileptiform abnormalities. Mild LD patients had NHLRC1 mutations and five of six carried homozygous or compound heterozygous D146N mutation. This mutation was found in none of the patients with typical LD. The occurrence of specific NHLRC1 mutations in patients with mild LD should be taken into account in clinical practice for appropriate management and counseling.

PTG protein depletion rescues malin-deficient Lafora disease in mouse.

Ubiquitin ligases regulate quantities and activities of target proteins, often pleiotropically. The malin ubiquitin E3 ligase is reported to regulate autophagy, the misfolded protein response, microRNA silencing, Wnt signaling, neuronatin-mediated endoplasmic reticulum stress, and the laforin glycogen phosphatase. Malin deficiency causes Lafora disease, pathologically characterized by neurodegeneration and accumulations of malformed glycogen (Lafora bodies). We show that reducing glycogen production in malin-deficient mice by genetically removing PTG, a glycogen synthesis activator protein, nearly completely eliminates Lafora bodies and rescues the neurodegeneration, myoclonus, seizure susceptibility, and behavioral abnormality. Glycogen synthesis downregulation is a potential therapy for the fatal adolescence onset epilepsy Lafora disease.

Lafora disease: epidemiology, pathophysiology and management.

Lafora disease is a rare, fatal, autosomal recessive, progressive myoclonic epilepsy. It may also be considered as a disorder of carbohydrate metabolism because of the formation of polyglucosan inclusion bodies in neural and other tissues due to abnormalities of the proteins laforin or malin. The condition is characterized by epilepsy, myoclonus and dementia. Diagnostic findings on MRI and neurophysiological testing are not definitive and biopsy or genetic studies may be required. Therapy in Lafora disease is currently limited to symptomatic management of the epilepsy, myoclonus and intercurrent complications. With a greater understanding of the pathophysiological processes involved, there is justified hope for future therapies.

Fixation-sensitive myoclonus in Lafora disease.

The authors report a patient with Lafora disease, whose myoclonus was suppressed by passive eye closure. Neurophysiologic studies disclosed that fixation was the most important enhancer of myoclonus. Magnetoencephalographic studies of visual evoked fields revealed abnormal activation of the visual corticocortical pathway via the insular cortex not seen in controls. The authors hypothesize that abnormal activation of the insular cortex may be involved in triggering the mechanism of fixation-sensitive myoclonus.

Progressive myoclonic epilepsies: a review of genetic and therapeutic aspects.

The progressive myoclonic epilepsies (PMEs) are a group of symptomatic generalised epilepsies caused by rare disorders, most of which have a genetic component, a debilitating course, and a poor outcome. Challenges with PME arise from difficulty with diagnosis, especially in the early stages of the illness, and further problems of management and drug treatment. Recent advances in molecular genetics have helped achieve better understanding of the different disorders that cause PME. We review the PMEs with emphasis on updated genetics, diagnosis, and therapeutic options.