EEG Patterns Orienting to Lafora Disease Diagnosis-A Case Report in Two Beagles

Clinical Signs in 166 Beagles with Different Genotypes of Lafora

Lafora disease (LD) is a genetic disease affecting beagles, resulting in seizures in combination with other signs. The aim of this study was to describe the clinical signs of LD in beagles with different NHLRC1 genotypes. One hundred and sixty-six beagles were tested for an NHLRC1 gene defect: L/L (n = 67), N/L (n = 32), N/N (n = 67). Owners were asked to participate in a survey about the clinical signs of LD in their dogs. These were recorded for the three possible genotypes in the two age groups, <6 years and ≥6 years. In all genotypes, nearly all the signs of LD were described. In the age group ≥ 6 years, however, they were significantly more frequent in beagles with the L/L genotype. If the following three clinical signs occur together in a beagle ≥ 6 years-jerking of the head, photosensitivity and forgetting things he/she used to be able to do-98.2% of these dogs are correctly assigned to the L/L genotype. If one or two of these signs are missing, the correct classification decreases to 92.1% and 13.2%, respectively. Only the combination of certain signs truly indicates the L/L genotype. Yet, for many dogs, only genetic testing will provide confirmation of the disease.

Retinal Phenotyping of a Murine Model of Lafora Disease

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 cFigure mparable 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.

A Novel Mutation in Lafora Disease and Update on Pathophysiology and Future Treatments

Lafora disease is a rare refractory epilepsy that results in death. This report highlights two cases of lafora disease and introduces a novel mutation in the patients. A review of the pathophysiology and future therapies is reviewed.

A retrospective case series of clinical signs in 28 Beagles with Lafora disease

BACKGROUND

Clinical signs and their progression in Beagles with Lafora disease are poorly described.

OBJECTIVES

To describe clinical signs in Beagles with Lafora disease.

ANIMALS

Twenty-eight Beagles with Lafora disease confirmed by genetic testing or histopathology.

METHODS

Retrospective multicenter case series. Data regarding signalment, clinical signs, diagnostic tests and treatment were retrieved from hospital data files. A questionnaire was sent to owners asking about neurological deficits, changes in cognitive functions, behavioral changes, response to treatment and survival time.

RESULTS

Onset of clinical signs was 8.3 years (mean; range, 6.3-13.3). All dogs had myoclonic episodes as an initial clinical sign with tonic-clonic seizures in n = 11/28 (39%) and n = 12/28 (43%) later developing tonic-clonic seizures. Deficits of coordination (n = 21/25; 84%), impaired vision (n = 15/26; 58%), and impaired hearing (n = 13/26; 50%) developed later. Mental decline was observed as loss of house training (urination; n = 8/25; 32%), difficulties performing learned tasks (n = 9/25; 36%), and difficulties learning new tasks (n = 7/23; 30%). Common behavioral changes were: increased photosensitivity (n = 20/26; 77%), staring into space (n = 16/25; 64%), reduced stress resistance (n = 15/26; 58%), increased noise sensitivity (n = 14/26; 54%), and separation anxiety (n = 11/25; 44%). Twenty-one dogs were alive (median age 11.9 years; range, 9.8-18.6), and 7 dogs were dead (mean age 12.1 years; SD: 1.3; range, 10.5-12.6) at time of writing.

CONCLUSIONS AND CLINICAL IMPORTANCE

Lafora disease in Beagles causes significant behavioral changes, and mental decline as well as neurological deficits in addition to myoclonic episodes and generalized tonic-clonic seizures. Nevertheless, a relatively normal life span can be expected.

NHLRC1 homozygous dodecamer expansion in a Newfoundland dog with Lafora disease

Lafora disease is a genetic disease caused, in humans, by mutations in EPM2A and NHLRC1 genes, resulting in accumulation of polyglucosan bodies within neurons. Affected subjects present progressive neurological signs characterised primarily by myoclonic epilepsy. In dogs, Lafora disease has been described mainly in miniature wire-haired Dachshunds, where a dodecamer expansion in NHLRC1 gene has been identified. The same mutation has then been detected in the Basset Hound, Beagle, Chihuahua and Pembroke Welsh Corgi breeds. This is the first case of a Newfoundland dog with myoclonic epilepsy diagnosed with Lafora disease based on confirmed dodecamer expansion in the NHLRC1 gene. Lafora disease is being progressively recognised in different unrelated breeds suggesting a wider distribution in the canine population than previously thought.