Lafora disease in miniature Wirehaired Dachshunds.

Lafora disease (LD) is an autosomal recessive late onset, progressive myoclonic epilepsy with a high prevalence in the miniature Wirehaired Dachshund. The disease is due to a mutation in the Epm2b gene which results in intracellular accumulation of abnormal glycogen (Lafora bodies). Recent breed-wide testing suggests that the carrier plus affected rate may be as high as 20%. A characteristic feature of the disease is spontaneous and reflex myoclonus; however clinical signs and disease progression are not well described. A survey was submitted to owners of MWHD which were homozygous for Epm2b mutation (breed club testing program) or had late onset reflex myoclonus and clinical diagnosis of LD. There were 27 dogs (11 male; 16 female) for analysis after young mutation-positive dogs that had yet to develop disease were excluded. Average age of onset of clinical signs was 6.94 years (3.5-12). The most common initial presenting sign was reflex and spontaneous myoclonus (77.8%). Other presenting signs included hypnic myoclonus (51.9%) and generalized seizures (40.7%). Less common presenting signs include focal seizures, "jaw smacking", "fly catching", "panic attacks", impaired vision, aggression and urinary incontinence. All these clinical signs may appear, and then increase in frequency and intensity over time. The myoclonus in particular becomes more severe and more refractory to treatment. Signs that developed later in the disease include dementia (51.9%), blindness (48.1%), aggression to people (25.9%) and dogs (33.3%), deafness (29.6%) and fecal (29.6%) and urinary (37.0%) incontinence as a result of loss of house training (disinhibited type behavior). Further prospective study is needed to further characterize the canine disease and to allow more specific therapeutic strategies and to tailor therapy as the disease progresses.

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: spectroscopy study correlated with neuropsychological findings.

PURPOSE: To evaluate the metabolic changes both in grey and white matter in Lafora disease using proton magnetic resonance spectroscopy and to determine the possible correlation with the pattern of cognitive impairment. METHODS: Five patients with Lafora disease and six healthy controls were included in the study. Patients underwent at the same time-point neuropsychological testing and 1[H]MRS, using PRESS sequences (TE=136 and 25 ms) positioned in the frontal and posterior cingulate gyrus cortexes and in the adjacent frontal and parietal white matter. RESULTS: Neuropsychological testing showed in all patients a prevalent involvement of performance abilities--with partial sparing of verbal competences--and of executive functions, suggesting a major involvement of frontal areas. Analysis of 1[H]MRS showed a statistically significant reduction in NAA/mI and NAA/Cr in grey matter of patients compared to controls, more significant in frontal regions. In white matter, a significant reduction of NAA/mI ratio was observed both in the frontal and parietal regions, associated with a reduction of the NAA/Cr only in the frontal white matter. NAA/mI was found to be the most statistically significant altered parameter in all regions studied and the only significantly altered ratio in strong correlation with all sets of neuropsychological parameters. CONCLUSIONS: Our study confirmed the predominant metabolic damage in the frontal cortex, also demonstrating NAA/mI ratio to be the most sensitive parameter to detect metabolic brain changes in Lafora disease; moreover, it evidenced frontal white matter spectroscopic changes. Both spectroscopy values and clinical features of cognitive impairment showed a prevalent frontal impairment.

Late-onset and slow-progressing Lafora disease in four siblings with EPM2B mutation.

We report a family with four brothers affected by Lafora disease (LD). Mean age at onset was 19.5 years (range, 17-21). In all cases, the initial obvious symptoms were diffuse myoclonus and occasional generalized tonic-clonic seizures (GTCSs), followed by cognitive difficulties. Severity of myoclonus, seizure diaries, and neurologic and neuropsychological status were finally evaluated in March 2005. The duration of follow-up was >10 years for three subjects. Daily living activities and social interaction were preserved in all cases and, overall, the progression of the disease was slow. Genetic study revealed the homozygous mutation D146N in the EPM2B gene. We suggest that this mutation may be associated with a less severe LD phenotype.

Unusual presentation of Lafora's disease.

Lafora's disease is a progressive myoclonus epilepsy with onset in adolescence and a gradual decline in cognitive functions and increase in seizure intractability. We present the case of a 16-year-old with precipitous dementia within 6 months of onset. Peripheral biopsies and EPM2A mutation analysis were negative. The diagnosis could be established only by brain biopsy.