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Lafora disease is a rare genetic disorder characterized by a disruption in glycogen metabolism. It manifests as progressive myoclonus epilepsy and cognitive decline during adolescence. Pathognomonic is the presence of abnormal glycogen aggregates that, over time, produce large inclusions (Lafora bodies) in various tissues. This study aims to describe the clinical and histopathological aspects of a novel Lafora disease patient, and to provide an update on the therapeutical advancements for this disorder. A 20-year-old Libyan boy presented with generalized tonic–clonic seizures, sporadic muscular jerks, eyelid spasms, and mental impairment. Electroencephalography showed multiple discharges across both brain hemispheres. Brain magnetic resonance imaging was unremarkable. Muscle biopsy showed increased lipid content and a very mild increase of intermyofibrillar glycogen, without the polyglucosan accumulation typically observed in Lafora bodies. Despite undergoing three lines of antiepileptic treatment, the patient's condition showed minimal to no improvement. We identified the homozygous variant c.137G>A, p.(Cys46Tyr), in the EPM2B/NHLRC1 gene, confirming the diagnosis of Lafora disease. To our knowledge, the presence of lipid aggregates without Lafora bodies is atypical. Lafora disease should be considered during the differential diagnosis of progressive, myoclonic, and refractory epilepsies in both children and young adults, especially when accompanied by cognitive decline. Although there are no effective therapies yet, the development of promising new strategies prompts the need for an early and accurate diagnosis. [ABSTRACT FROM AUTHOR]

Lafora disease (LD) is a progressive neurologic disorder caused by biallelic pathogenic variants in EPM2A or EPM2B, leading to tissue accumulation of polyglucosan aggregates termed Lafora bodies (LBs). This study aimed to characterize the retinal phenotype in Epm2a−/− mice by examining knockout (KO; Epm2a−/−) and control (WT) littermates at two time points (10 and 14 months, respectively). In vivo exams included electroretinogram (ERG) testing, optical coherence tomography (OCT) and retinal photography. Ex vivo retinal testing included Periodic acid Schiff Diastase (PASD) staining, followed by imaging to assess and quantify LB deposition. There was no significant difference in any dark-adapted or light-adapted ERG parameters between KO and WT mice. The total retinal thickness was comparable between the groups and the retinal appearance was normal in both groups. On PASD staining, LBs were observed in KO mice within the inner and outer plexiform layers and in the inner nuclear layer. The average number of LBs within the inner plexiform layer in KO mice were 1743 ± 533 and 2615 ± 915 per mm2, at 10 and 14 months, respectively. This is the first study to characterize the retinal phenotype in an Epm2a−/− mouse model, demonstrating significant LB deposition in the bipolar cell nuclear layer and its synapses. This finding may be used to monitor the efficacy of experimental treatments in mouse models. [ABSTRACT FROM AUTHOR]

Lafora disease is a rare genetic disorder characterized by a disruption in glycogen metabolism. It manifests as progressive myoclonus epilepsy and cognitive decline during adolescence. Pathognomonic is the presence of abnormal glycogen aggregates that, over time, produce large inclusions (Lafora bodies) in various tissues. This study aims to describe the clinical and histopathological aspects of a novel Lafora disease patient, and to provide an update on the therapeutical advancements for this disorder. A 20-year-old Libyan boy presented with generalized tonic–clonic seizures, sporadic muscular jerks, eyelid spasms, and mental impairment. Electroencephalography showed multiple discharges across both brain hemispheres. Brain magnetic resonance imaging was unremarkable. Muscle biopsy showed increased lipid content and a very mild increase of intermyofibrillar glycogen, without the polyglucosan accumulation typically observed in Lafora bodies. Despite undergoing three lines of antiepileptic treatment, the patient’s condition showed minimal to no improvement. We identified the homozygous variant c.137G>A, p.(Cys46Tyr), in the EPM2B/NHLRC1 gene, confirming the diagnosis of Lafora disease. To our knowledge, the presence of lipid aggregates without Lafora bodies is atypical. Lafora disease should be considered during the differential diagnosis of progressive, myoclonic, and refractory epilepsies in both children and young adults, especially when accompanied by cognitive decline. Although there are no effective therapies yet, the development of promising new strategies prompts the need for an early and accurate diagnosis.

We report a case of progressive myoclonic epilepsy caused by a novel mutation in EPM2A. The female patient experienced abnormal jerky movements of the involving all four limbs and several generalized seizures, degeneration of cognition, and unsteadiness. Genetic analysis identified two rare, deleterious mutations in exon4: chr6: 145,948,751(c.G797G > A) and chr6: 145,948,761(c.T787C > T). The mutations at these two loci were from the genomes of their mother and father, respectively, which were compound heterozygous variations. This report updates the mutation sites of gene EPM2A and extends genotype-phenotype correlations in Lafora disease. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Lafora body disease (MIM-254780), a glycogen storage disease, characterized by Lafora bodies (deformed glycogen molecules) accumulating in multiple organs, is a rare form of myoclonic epilepsy. It manifests in early adolescent years, initially with seizures and myoclonus, followed by dementia and progressive cognitive decline, ultimately culminating in death within 10 years. In Pakistan so far 5 cases have been reported. Here, we report a new case of Lafora body disease belonging to a consanguineous family from Pakistan. Histopathological analysis confirmed presence of lafora bodies in the patient`s skin. Sanger sequencing revealed novel homozygous 5bp deletion mutation (NM_005670.4; c.359_363delGTGTG) in exon 2 of the EPM2A gene, which was truly segregated in the family. These results will increase our understanding regarding the aetiology of this disorder and will further add to the mutation spectrum of EPM2A gene. [ABSTRACT FROM AUTHOR]

Abstract Background Lafora disease (LD) is a rare, lethal, progressive myoclonus epilepsy for which no targeted therapy is currently available. Studies on a mouse model of LD showed a good response to metformin, a drug with a well known neuroprotective effect. For this reason, in 2016, the European Medicines Agency granted orphan designation to metformin for the treatment of LD. However, no clinical data is available thus far. Methods We retrospectively collected data on LD patients treated with metformin referred to three Italian epilepsy centres. Results Twelve patients with genetically confirmed LD (6 EPM2A, 6 NHLRC1) at middle/late stages of disease were treated with add-on metformin for a mean period of 18 months (range: 6–36). Metformin was titrated to a mean maintenance dose of 1167 mg/day (range: 500–2000 mg). In four patients dosing was limited by gastrointestinal side-effects. No serious adverse events occurred. Three patients had a clinical response, which was temporary in two, characterized by a reduction of seizure frequency and global clinical improvement. Conclusions Metformin was overall safe in our small cohort of LD patients. Even though the clinical outcome was poor, this may be related to the advanced stage of disease in our cases and we cannot exclude a role of metformin in slowing down LD progression. Therefore, on the grounds of the preclinical data, we believe that treatment with metformin may be attempted as early as possible in the course of LD.

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. [ABSTRACT FROM AUTHOR]

Lafora disease is a fatal teenage-onset progressive myoclonus epilepsy and neurodegenerative disease associated with polyglucosan bodies. Polyglucosans are long-branched and as a result precipitation- and aggregation-prone glycogen. In mouse models, downregulation of glycogen synthase, the enzyme that elongates glycogen branches, prevents polyglucosan formation and rescues Lafora disease. Mouse work, however, has not yet revealed the mechanisms of polyglucosan generation, and few in vivo human studies have been performed. Here, non-invasive in vivo magnetic resonance spectroscopy ( 1 H and 31 P) was applied to test scan feasibility and assess neurotransmitter balance and energy metabolism in Lafora disease towards a better understanding of pathogenesis. Macromolecule-suppressed gamma-aminobutyric acid (GABA)-edited 1 H magnetic resonance spectroscopy and 31 P magnetic resonance spectroscopy at 3 and 7 tesla, respectively, were performed in 4 Lafora disease patients and a total of 21 healthy controls (12 for the 1 H magnetic resonance spectroscopy and 9 for the 31 PMRS). Spectra were processed using in-house software and fit to extract metabolite concentrations. From the 1 H spectra, we found 33% lower GABA concentrations ( P = 0.013), 34% higher glutamate + glutamine concentrations ( P = 0.011) and 24% lower N -acetylaspartate concentrations ( P = 0.0043) in Lafora disease patients compared with controls. From the 31 P spectra, we found 34% higher phosphoethanolamine concentrations ( P = 0.016), 23% lower nicotinamide adenine dinucleotide concentrations ( P = 0.003), 50% higher uridine diphosphate glucose concentrations ( P = 0.004) and 225% higher glucose 6-phosphate concentrations in Lafora disease patients versus controls ( P = 0.004). Uridine diphosphate glucose is the substrate of glycogen synthase, and glucose 6-phosphate is its extremely potent allosteric activator. The observed elevated uridine diphosphate glucose and glucose 6-phosphate levels are expected to hyperactivate glycogen synthase and may underlie the generation of polyglucosans in Lafora disease. The increased glutamate + glutamine and reduced GABA indicate altered neurotransmission and energy metabolism, which may contribute to the disease's intractable epilepsy. These results suggest a possible basis of polyglucosan formation and potential contributions to the epilepsy of Lafora disease. If confirmed in larger human and animal model studies, measurements of the dysregulated metabolites by magnetic resonance spectroscopy could be developed into non-invasive biomarkers for clinical trials., Competing Interests: The authors report no competing interests., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain.)

EPM2A has been certified as a causative gene in patients with Lafora disease (LD), which is a rare autosomal recessive and severe form of progressive myoclonus epilepsy. LD classically starts in adolescence, characterized by various types of seizure with myoclonic seizure as the main type. Typically within 10 years, intractable seizure attack, rapidly progressing dementia, and a vegetative state were present. LD is particularly frequently found in Mediterranean countries. Here, we report a Chinese family with a novel compound heterozygous mutation in the EPM2A gene, characterized by recurrent vomiting, intractable epilepsy, and progressive cognitive decline. [ABSTRACT FROM AUTHOR]

Purpose: To describe cerebral glucose metabolism pattern as assessed by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in Lafora disease (LD), a rare, lethal form of progressive myoclonus epilepsy caused by biallelic mutations in EPM2A or NHLRC1. Methods: We retrospectively included patients with genetically confirmed LD who underwent FDG-PET scan referred to three Italian epilepsy centers. FDG-PET images were evaluated both visually and using SPM12 software. Subgroup analysis was performed on the basis of genetic and clinical features employing SPM. Moreover, we performed a systematic literature review of LD cases that underwent FDG-PET assessment. Results: Eight Italian patients (3M/5F, 3 EPM2A/5 NHLRC1) underwent FDG-PET examination after a mean of 6 years from disease onset (range 1–12 years). All patients showed bilateral hypometabolic areas, more diffuse and pronounced in advanced disease stages. Most frequently, the hypometabolic regions were the temporal (8/8), parietal (7/8), and frontal lobes (7/8), as well as the thalamus (6/8). In three cases, the FDG-PET repeated after a mean of 17 months (range 7–36 months) showed a metabolic worsening compared with the baseline examination. The SPM subgroup analysis found no significant differences based on genetics, whereas it showed a more significant temporoparietal hypometabolism in patients with visual symptoms compared with those without. In nine additional cases identified from eight publications, FDG-PET showed heterogeneous findings, ranging from diffusely decreased cerebral glucose metabolism to unremarkable examinations in two cases. Conclusions: FDG-PET seems highly sensitive to evaluate LD at any stage and may correlate with disease progression. Areas of decreased glucose metabolism in LD are extensive, often involving multiple cortical and subcortical regions, with thalamus, temporal, frontal, and parietal lobes being the most severely affected. Prospective longitudinal collaborative studies are needed to validate our findings. [ABSTRACT FROM AUTHOR]

Canine Lafora disease is a recessively inherited, rapidly progressing neurodegenerative disease caused by the accumulation of abnormally constructed insoluble glycogen Lafora bodies in the brain and other tissues due to the loss of NHL repeat containing E3 ubiquitin protein ligase 1 (NHLRC1). Dogs have a dodecamer repeat sequence within the NHLRC1 gene, which is prone to unstable (dynamic) expansion and loss of function. Progressive signs of Lafora disease include hypnic jerks, reflex and spontaneous myoclonus, seizures, vision loss, ataxia and decreased cognitive function. We studied five dogs (one Chihuahua, two French Bulldogs, one Griffon Bruxellois, one mixed breed) with clinical signs associated with canine Lafora disease. Identification of polyglucosan bodies (Lafora bodies) in myocytes supported diagnosis in the French Bulldogs; muscle areas close to the myotendinous junction and the myofascial union segment had the highest yield of inclusions. Postmortem examination of one of the French Bulldogs revealed brain Lafora bodies. Genetic testing for the known canine NHLRC1 mutation confirmed the presence of a homozygous mutation associated with canine Lafora disease. Our results show that Lafora disease extends beyond previous known breeds to the French Bulldog, Griffon Bruxellois and even mixed-breed dogs, emphasizing the likely species-wide nature of this genetic problem. It also establishes these breeds as animal models for the devastating human disease. Genetic testing should be used when designing breeding strategies to determine the frequency of the NHLRC1 mutation in affected breeds. Lafora diseases should be suspected in any older dog presenting with myoclonus, hypnic jerks or photoconvulsions.

Lafora disease (LD) is a rare autosomal recessive disorder characterized by progressive myoclonic epilepsy followed by continuous neurological decline, culminating in death within 10 years. LD leads to accumulation of insoluble, abnormal, glycogen–like structures called Lafora bodies (LBs). It is caused by mutations in the gene encoding glycogen phosphatase (EPM2A) or the E3 ubiquitin ligase malin (EPM2B/NHLRC1). These two proteins are involved in an intricate, however, incompletely elucidated pathway governing glycogen metabolism. The formation of EPM2A and malin signaling complex promotes the ubiquitination of proteins participating in glycogen metabolism, where dysfunctional mutations lead to the formation of LBs. Herein, we describe a 13-years-old child with LD due to a NHLRC1 (c.386C > A, p.Pro129His) mutation, who has developed diabetes mellitus and was treated with metformin. We discuss how basic mechanisms of LD could be linked to β-cell dysfunction and insulin resistance.

Preeclampsia (PE) is a maternal multisystem disease with an unclear mechanism. Data showed that MiR-95-3p promoted cell migration, invasion and proliferation, leading to the occurrence and development of many cancers, and placental trophoblasts and tumor cells had similar migration, invasion and proliferation abilities. Meanwhile we found that MiR-95-3p was differentially expressed in PE and normal placenta. Therefore, this article aimed to explore the biological function and mechanism of miR-95-3p in PE. The expression of miR-95-3p in PE and normal placental tissue was explored by high-throughput sequencing and qRT–PCR. The effects of miR-95-3p on trophoblast migration, invasion, proliferation, angiogenesis and apoptosis were investigated by Transwell migration and invasion assays, cell viability assay, tube formation assay and flow cytometry in two trophoblast cell lines (HTR-8/SVneo and JAR). The miR-95-3p target gene EPM2A was identified and verified by unique identifier mRNA next-generation sequencing and dual-luciferase reporter gene experiments. Rescue experiments were conducted to investigate whether miR-95-3p regulated EPM2A to participate in trophoblast migration and invasion. Finally, the effects of miR-95-3p and EPM2A on the expression of angiogenic factors and inflammation-related factors were investigated by ELISA. We found that miR-95-3p was expressed at low levels in the placental tissue of patients with PE and was negatively correlated with EPM2A expression. In vitro upregulation of miR-95-3p and downregulation of EPM2A promote trophoblast migration, invasion and proliferation. Furthermore, EPM2A was confirmed as a target mRNA of miR-95-3p. Upregulation of EPM2A mitigated miR-95-3p-mediated promotion of trophoblast migration and invasion and vice versa. Finally, both miR-95-3p and EPM2A regulate the expression of trophoblast angiogenesis-related factors and inflammation-related factors. Our findings demonstrated that miR-95-3p promoted the migration and invasion of trophoblast cells by targeting EPM2A to inhibit the occurrence and development of PE. [Display omitted] • MiR-95-3p was downregulated and EPM2A was upregulated in PE placentas. • MiR-95-3p downregulation could inhibit trophoblast migration, invasion and proliferation by targeting EPM2A, and EPM2A limited the ability of miR-95-3p to affect trophoblast biological behaviour. [ABSTRACT FROM AUTHOR]

Lafora disease (LD) is progressive myoclonic epilepsy with late childhood- to teenage-onset. Mutations in two genes, EPM2A and NHLRC1 , are responsible for this autosomal recessive disease in many patients Worldwide. In present study, we reported two unrelated consanguineous Pakistani families with Lafora disease (Families A and B). Affected individuals in both families presented with generalized tonic clonic seizures, intellectual disability, ataxia and cognitive decline. Diagnosis of Lafora disease was made on histo-pathological analysis of the skin biopsy, found positive for lafora bodies in periodic acid schiff stain and frequent generalized epileptiform discharges on electroencephalogram (EEG). Bi-directional sequencing in family A was performed for EPM2A and NHLRC1 genes but no mutation was found. In family B, Illumina TruSight One Sequencing Panel covering 4813 OMIM genes was carried out and we identified a novel homozygous mutation c.95G > T; p.32Trp > Leu of EPM2A gene which was found co-segregated in this family through Sanger sequencing. Structural analysis of this mutation, through different in silico approaches, predicted loss of stability and conformation in Laforin protein. [ABSTRACT FROM AUTHOR]

Lafora disease is a form of progressive myoclonic epilepsy with autosomal recessive transmission. Two genes have been identified so far: EPM2A and NHLRC1, and a third gene, concerning a pediatric onset subform, has been recently proposed. We report the case of a 23-year-old woman of Turkish origin with an unusual disease course. Clinical onset was at the age of 19 years with tonic–clonic seizures, followed by cognitive impairment; EEG was in favor of Lafora disease, and the mutation c.436G>A (a missense mutation substituting aspartic acid in asparagine) in the NHLRC1 gene confirmed this diagnosis. After 5 years of evolution, the patient only has moderate cognitive impairment. Some NHLRC1 mutations, particularly c.436G>A, are associated with a slower clinical course, but there are conflicting data in the literature. This case strengthens the hypothesis that the c.436G>A mutation in the NHLRC1 gene leads to less severe phenotypes and late-onset disease.

Lafora disease (LD) is an autosomal recessive progressive myoclonus epilepsy due to mutations in the EPM2A (laforin) and EPM2B (malin) genes, with no substantial genotype-phenotype differences between the two. Founder effects and recurrent mutations are common, and mostly isolated to specific ethnic groups and/or geographical locations. Pathologically, LD is characterized by distinctive polyglucosans, which are formations of abnormal glycogen. Polyglucosans, or Lafora bodies (LB) are typically found in the brain, periportal hepatocytes of the liver, skeletal and cardiac myocytes, and in the eccrine duct and apocrine myoepithelial cells of sweat glands. Mouse models of the disease and other naturally occurring animal models have similar pathology and phenotype. Hypotheses of LB formation remain controversial, with compelling evidence and caveats for each hypothesis. However, it is clear that the laforin and malin functions regulating glycogen structure are key. With the exception of a few missense mutations LD is clinically homogeneous, with onset in adolescence. Symptoms begin with seizures, and neurological decline follows soon after. The disease course is progressive and fatal, with death occurring within 10 years of onset. Antiepileptic drugs are mostly non-effective, with none having a major influence on the progression of cognitive and behavioral symptoms. Diagnosis and genetic counseling are important aspects of LD, and social support is essential in disease management. Future therapeutics for LD will revolve around the pathogenesics of the disease. Currently, efforts at identifying compounds or approaches to reduce brain glycogen synthesis appear to be highly promising. [ABSTRACT FROM AUTHOR]

Background: We investigated phosphodiesterase 7B (PDE7B), neuromedin B receptor (NMBR) and epilepsy progressive myoclonus type 2A (EPM2A) genes in schizophrenia (SCZ). To the best of our knowledge, these genes have been poorly investigated in studies of SCZ. Methods: Five hundred and seventy-three SCZ inpatients of Korean ethnicity and 560 healthy controls were genotyped for 2 PDE7B, 3 NMBR and 3 EPM2A polymorphisms. Differences in the allelic and genetic frequencies among healthy subjects and patients were calculated using the 2 statistics. Repeatedmeasure ANOVA was used to test possible influences of single- nucleotide polymorphisms on treatment efficacy. In case of positive findings, clinical and demographic variables were added as covariates, in order to investigate possible stratification bias. Results: The rs2717 and rs6926279 within the NMBR gene and rs702304 and rs2235481 within the EPM2A gene were associated with SCZ liability. rs1415744 was also associated with Positive and Negative Symptom Scale negative clinical improvement. The results remained the same after inclusion of the covariates and were partially confirmed in the allelic and haplotype analyses. Conclusion: Our preliminary findings suggest a possible role of NMBR and EPM2A genes in SCZ susceptibility and, for the second one, also in antipsychotic pharmacogenetics. Nonetheless, further research is needed to confirm our findings. [ABSTRACT FROM AUTHOR]

Summary Lafora disease (LD) is an autosomal recessive progressive myoclonus epilepsy with classic adolescent onset of stimuli sensitive seizures. Patients typically deteriorate rapidly with dementia, ataxia, vegetative failure and death by 25 years of age. LD is caused by homozygous mutations in EPM2A or EPM2B genes. We found four novel mutations in EPM2A – three in exon 4 (Q247X, H265R G279C) and one in exon 1 (Y86D) – and a previously described mutation in exon 4 (R241X). These five EPM2A mutations were found in four index cases and affected relatives. Patient 1 with classic LD was doubly heterozygous for H265R and R241X in exon 4; while Patient 2, who also had classic LD, was homozygous for Q247X in exon 4. Patient 3 with classic LD was homozygous for Y86D in exon 1, but the same mutation in his affected brother manifested an atypical earlier childhood onset. For the first time, we describe a later onset and slower progression of EPM2A -deficient LD seen in Patient 4 and her three sisters who were doubly heterozygous for R241X and G279C in exon 4. In these sisters, seizures started later at 21 to 28 years of age and progressed slowly with patients living beyond 30 years of age. Our observations suggest that variations in phenotypes of EPM2A- deficient LD, like an earlier childhood or adolescent or later adult onset with a rapid or slower course, depend on a second modifying factor separate from pathogenicity or exon location of EPM2A mutations. A modifying gene amongst the patient's genetic background or environmental factors may condition age of onset and rapid or slow progression of LD. [ABSTRACT FROM AUTHOR]

Summary: Lafora disease (LD) is a type of autosomal recessive, progressive myoclonus epilepsy resulting mostly from mutations in the EPM2A and NHLRC1 genes. Mutational analysis in both genes was initiated with the aim of establishing LD DNA diagnosis in Turkey. Four novel NHLRC1 (p.G131X, p.P69S and p.D82H) and EPM2A (p.V7A) and two recurrent NHLRC1 (p.D146N) and EPM2A (p.R241X) mutations were identified in six families. The delineation of causative mutations in patients provided early disease diagnosis for other family members and contributed to the knowledge of LD pathogenesis. [ABSTRACT FROM AUTHOR]

Purpose: Lafora disease (LD) is an autosomal recessive form of progressive myoclonus epilepsy with onset in childhood or adolescence and with fatal outcome caused by mutations in two genes: EPM2A and NHLRC1. The aim of this study was to characterize the mutation spectrum in a cohort of unrelated patients with presumed LD. Methods: Sequencing of the two genes and search for large rearrangements was performed in 46 unrelated patients with suspected LD, 33 originating from France and the others from different countries. Patients were classified into two groups according to the clinical presentation. Results: Mutations of various types were found in EPM2A in 10 patients and in NHLRC1 in 4 patients. Mutations were found in 14 (93%) of 15 patients with classical clinical and electroencephalography (EEG) presentation of LD and in no patients with an atypical presentation. Ten mutations were novel, including the first substitution reported in a donor splice site of EPM2A, leading to the deletion of exon 2 at the RNA level. Four large deletions, including two deletions of exon 2 with different sizes and breakpoints, were found in EPM2A, corresponding to 20% of the alleles of this gene. Discussion: We described several novel mutations of EPM2A and NHLRC1 and brought additional data to the genetic epidemiology of LD. This study emphasized the high mutation rate in patients with classical LD as well as the high negativity rate of skin biopsy. [ABSTRACT FROM AUTHOR]

Lafora disease is a progressive myoclonus epilepsy with onset typically in the second decade of life and death within 10 years. Lafora bodies, deposits of abnormally branched, insoluble glycogen-like polymers, form in neurons, muscle, liver, and other tissues. Approximately half of the cases of Lafora disease result from mutations in the EPM2A gene, which encodes laforin, a member of the dual-specificity protein phosphatase family that additionally contains a glycogen binding domain. The molecular basis for the formation of Lafora bodies is completely unknown. Glycogen, a branched polymer of glucose, contains a small amount of covalently linked phosphate whose origin and function are obscure. We report here that recombinant laforin is able to release this phosphate in vitro, in a time-dependent reaction with an apparent Km for glycogen of 4.5 mg/ml. Mutations of laforin that disable the glycogen binding domain also eliminate its ability to dephosphorylate glycogen. We have also analyzed glycogen from a mouse model of Lafora disease, Epm2a-/- mice, which develop Lafora bodies in several tissues. Glycogen isolated from these mice had a 40% increase in the covalent phosphate content in liver and a 4-fold elevation in muscle. We propose that excessive phosphorylation of glycogen leads to aberrant branching and Lafora body formation. This study provides a molecular link between an observed biochemical property of laforin and the phenotype of a mouse model of Lafora disease. The results also have important implications for glycogen metabolism generally. [ABSTRACT FROM AUTHOR]

Lafora disease (LD) is a rare autosomal recessive genetic disorder characterized by epilepsy, myoclonus, and progressive neurological deterioration. LD is caused by mutations in the EMP2A gene encoding a protein phosphatase. A second gene for LD, termed NHLRC1 and encoding a putative E3 ubiquitin ligase, was recently identified on chromosome 6p22. The LD is relatively common in southern Europe, the Middle East, and Southeast Asia. A few sporadic cases with typical LD phenotype have been reported from Japan; however, our earlier study failed to find EPM2A mutations in four Japanese families with LD. We recruited four new families from Japan and searched for mutations in EPM2A . All eight families were also screened for NHLRC1 mutations. We found five independent families having novel mutations in NHLRC1. Identified mutations include five missense mutations (p.I153M, p.C160R, p.W219R, p.D245N, and p.R253K) and a deletion mutation (c.897insA; p.S299fs13). We also found a family with a ten base pair deletion (c.822-832del10) in the coding region of EPM2A. In two families, no EPM2A or NHLRC1 mutation was found. Our study, in addition to documenting the genetic and molecular heterogeneity observed for LD, suggests that mutations in the NHLRC1 gene may be a common cause of LD in the Japanese population. [ABSTRACT FROM AUTHOR]

Lafora disease (LD) is an autosomal recessive inherited form of progressive myoclonic epilepsy with dementia and ataxia, usually presenting in the second decade of life and inexorably progressing until death. Neuropathological hallmarks are Lafora bodies, intracytoplasmic inclusions that can be found in neurons and in other tissues. LD gene (EPM2A), mapping on chromosome 6, encodes for a tyrosine phosphatase protein called laforin. However, up to 20% cases of LD are not genetically linked to chromosome 6. We report two sisters affected from bioptically diagnosed LD but without evidence of EPM2A mutation. Although familial cases of LD are already reported in literature, our observation leads to some considerations on clinical–electrophysiological evolution as well as to remark the genetic heterogeneity of this condition. In addition, we report the good effect of the Levetiracetam for the treatment of myoclonus in these patients, also demonstrated by the electrophysiological findings. [Copyright &y& Elsevier]

We have identified an interacting partner protein (encoded by the human EPM2AIP1 gene (approved symbol)) for laforin, the product of the EPM2A gene, which is mutated in an autosomal recessive form of adolescent progressive myoclonus epilepsy. The EPM2AIP1 gene was identified in a screen for laforin-interacting proteins with a human brain cDNA library using the yeast two-hybrid system. The specificity of the interaction was confirmed by coimmunoprecipitation of in vivo-transfected protein and by using EPM2A deletion constructs. Subcellular colocalization of laforin and EPM2AIP1 protein was also demonstrated. The human EPM2AIP1 gene, corresponding to the KIAA0766 cDNA clone in the databases, was characterized and shown, like EPM2A, to be ubiquitously expressed. The gene, which comprises one large exon 1824 nucleotides in length and has alternative 3′ untranslated regions, maps to human chromosome 3p22.1. The function is currently not known and extensive analyses do not reveal any homology to other proteins or any obvious structural motifs. Because genetic heterogeneity in Lafora disease has been described, mutational analysis of the EPM2AIP1 gene was performed on non-EPM2A patients, but no mutations were found. The identification of this first binding partner for laforin promises to be an important step toward unraveling the underlying pathogenesis of this severest form of teenage-onset epilepsy. [Copyright &y& Elsevier]

Laforin is a dual-specificity phosphatase coded by the EPM2A gene defective in Lafora''s progressive myoclonus epilepsy. We reported earlier that laforin is a cytoplasmic protein associated primarily with polyribosome. In the present study we characterized the expression of an EPM2A splice variant, named C-terISO, originating from the usage of a novel exon located in the 3′-untranslated region of exon 4 and encoding a laforin isoform containing unique sequences at its carboxyl terminus. Transfection studies demonstrate that, in addition to cytoplasm, the protein coded by C-terISO was targeted to the nucleus, a distinctive feature that was not observed for laforin coded by the major transcript of the EPM2A gene. The unique C-terminal sequence did not affect laforin''s affinity for polysome, but sequestered nearly an equal amount of the protein into the nucleus. Our results are significant in light of the finding that laforin is an active phosphatase; therefore, isoforms targeted to different cellular compartments might dephosphorylate and regulate distinct cellular substrates. [Copyright &y& Elsevier]

A 19-year-old male patient presented with progressive myoclonic seizures and speech disorder. The patient had photosensitivity, a few episodes of sudden transient blindness, and infrequent complex visual auras, dysarthria and mild ataxia, frequent myoclonic jerks prominently in the legs and severe dementia. Microscopic examination of the axillary skin biopsy revealed periodic acid-Schiff positive inclusion bodies in abluminal side of the apocrine sweat gland acini. Molecular screening showed a homozygous R241X mutation in EPM2A. Genotyping helps in the correct diagnosis of the Lafora disease (LD), which may be difficult to diagnose based on the available histopathological testing only. Our study is an effort to determine the distribution of mutations in LD patients in our region.

Canine Lafora disease is a recessively inherited, rapidly progressing neurodegenerative disease caused by the accumulation of abnormally constructed insoluble glycogen Lafora bodies in the brain and other tissues due to the loss of NHL repeat containing E3 ubiquitin protein ligase 1 (NHLRC1). Dogs have a dodecamer repeat sequence within the NHLRC1 gene, which is prone to unstable (dynamic) expansion and loss of function. Progressive signs of Lafora disease include hypnic jerks, reflex and spontaneous myoclonus, seizures, vision loss, ataxia and decreased cognitive function. We studied five dogs (one Chihuahua, two French Bulldogs, one Griffon Bruxellois, one mixed breed) with clinical signs associated with canine Lafora disease. Identification of polyglucosan bodies (Lafora bodies) in myocytes supported diagnosis in the French Bulldogs; muscle areas close to the myotendinous junction and the myofascial union segment had the highest yield of inclusions. Postmortem examination of one of the French Bulldogs revealed brain Lafora bodies. Genetic testing for the known canine NHLRC1 mutation confirmed the presence of a homozygous mutation associated with canine Lafora disease. Our results show that Lafora disease extends beyond previous known breeds to the French Bulldog, Griffon Bruxellois and even mixed-breed dogs, emphasizing the likely species-wide nature of this genetic problem. It also establishes these breeds as animal models for the devastating human disease. Genetic testing should be used when designing breeding strategies to determine the frequency of the NHLRC1 mutation in affected breeds. Lafora diseases should be suspected in any older dog presenting with myoclonus, hypnic jerks or photoconvulsions. [ABSTRACT FROM AUTHOR]

Lafora disease (LD) is characterized by progressive myoclonus, refractory epilepsy, and cognitive deterioration. This complex neurodegenerative condition is caused by pathogenic variants in EPM2A / EPM2B genes, encoding two essential glycogen metabolism enzymes known as laforin and malin. Long-term follow-up data are lacking. We describe the clinical features and genetic findings of a cohort of 26 Italian patients with a long clinical follow-up. Patients with EPM2A/EPM2B pathogenic variants were identified by direct gene sequencing or gene panels with targeted re-sequencing. Disease progression, motor functions, and mental performance were assessed by a simplified disability scale. Spontaneous/action myoclonus severity was scored by the Magaudda Scale. Age range was 12.2–46.2 years (mean:25.53 ± 9.14). Age at disease onset ranged from 10 to 22 years (mean:14.04 ± 2.62). The mean follow-up period was 11.48 ± 7.8 years. Twelve out of the 26 (46%) patients preserved walking ability and 13 (50%) maintained speech. A slower disease progression with preserved ambulation and speech after ≥4 years of follow-up was observed in 1 (11%) out of the 9 (35%) EPM2A patients and in 6 (35%) out of the 17 (65%) EPM2B patients. Follow-up was >10 years in 7 (41.2%) EPM2B individuals, including two harbouring the homozygous p.(D146N) pathogenic variant. This study supports an overall worse disease outcome with severe deterioration of ambulation and speech in patients carrying EPM2A mutations. However, the delayed onset of disabling symptoms observed in the EPM2B subjects harbouring the p.(D146N) pathogenic variant suggests that the underlying causative variant may still influence LD severity. [Display omitted] • We report 26 Italian individuals with a mean follow-up of 11.48 ± 7.8 years. • Twelve out of 26 (46%) patients preserved ambulation and 13 (50%) maintained speech. • Follow-up was >10 years in 7 (41.2%) EPM2B individuals. • Disease course was slower in patients harbouring the p.(D146N) variant in EPM2B. • Severe deterioration of ambulation and speech occur in LD patients carrying EPM2A. [ABSTRACT FROM AUTHOR]

Abstract: We report a Tunisian patient born from consanguineous marriage affected with progressive myoclonus epilepsy and cognitive decline, consistent with the diagnosis of Lafora disease. Genetic analysis showed a novel c.659T>A mutation on exon 3 of the EPM2A gene, converting a leucine to a glutamine residue at amino acid position 220 (p.Leu220Gln), in the dual-specificity phosphatase domain. [Copyright &y& Elsevier]

Glycogen is a branched polymer of glucose that acts as an energy reserve in many cell types. Glycogen contains trace amounts of covalent phosphate, in the range of 1 phosphate per 500-2000 glucose residues depending on the source. The function, if any, is unknown, but in at least one genetic disease, the progressive myoclonic epilepsy Lafora disease, excessive phosphorylation of glycogen has been implicated in the pathology by disturbing glycogen structure. Some 90% of Lafora cases are attributed to mutations of the EPM2A or EPM2B genes, and mice with either gene disrupted accumulate hyperphosphorylated glycogen. It is, therefore, of importance to understand the chemistry of glycogen phosphorylation. Rabbit skeletal muscle glycogen contained covalent phosphate as monoesters of C2, C3, and C6 carbons of glucose residues based on analyses of phospho-oligosaccharides by NMR. Furthermore, using a sensitive assay for glucose 6-P in hydrolysates of glycogen coupled with measurement of total phosphate, we determined the proportion of C6 phosphorylation in rabbit muscle glycogen to be ∼20%. C6 phosphorylation also accounted for ∼20% of the covalent phosphate in wild type mouse muscle glycogen. Glycogen phosphorylation in Epm2a(-/-) and Epm2b(-/-) mice was increased 8- and 4-fold compared with wild type mice, but the proportion of C6 phosphorylation remained unchanged at ∼20%. Therefore, our results suggest that C2, C3, and/or C6 phosphate could all contribute to abnormal glycogen structure or to Lafora disease., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)