[Lafora's disease (EPM2)]

Natural history of Lafora disease: a prognostic systematic review and individual participant data meta-analysis

Background

Lafora disease (LD) is a rare fatal autosomal recessive form of progressive myoclonus epilepsy. It affects previously healthy children or adolescents, causing pharmacoresistant epilepsy, myoclonus and severe psychomotor deterioration. This work aims to describe the clinical course of LD and identify predictors of outcome by means of a prognostic systematic review with individual participant data meta-analysis.

Methods

A search was conducted on MEDLINE and Embase with no restrictions on publication date. Only studies reporting genetically confirmed LD cases were included. Kaplan–Meier estimate was used to assess probability of death and loss of autonomy. Univariable and multivariable Cox regression models with mixed effects (clustered survival data) were performed to evaluate prognostic factors.

Results

Seventy-three papers describing 298 genetically confirmed LD cases were selected. Mean age at disease onset was 13.4 years (SD 3.7), with 9.1% aged ≥ 18 years. Overall survival rates in 272 cases were 93% [95% CI 89–96] at 5 years, 62% [95% CI 54–69] at 10 years and 57% [95% CI 49–65] at 15 years. Median survival time was 11 years. The probability of loss of autonomy in 110 cases was 45% [95% CI 36–55] at 5 years, 75% [95% CI 66–84] at 10 years, and 83% [95% CI 74–90] at 15 years. Median loss of autonomy time was 6 years. Asian origin and age at onset < 18 years emerged as negative prognostic factors, while type of mutated gene and symptoms at onset were not related to survival or disability.

Conclusions

This study documented that half of patients survived at least 11 years. The notion of actual survival rate and prognostic factors is crucial to design studies on the effectiveness of upcoming new disease-modifying therapies.

The Madrid School of Neurology (1885-1939)

The emergence of neurology in Madrid between 1885 and 1939 had well-defined characteristics. On foundations laid by Cajal and Río-Hortega, pioneers combined clinical practice with cutting-edge neurohistology and neuropathology research. Luis Simarro, trained in Paris, taught many talented students including Gayarre, Achúcarro and Lafora. The untimely death of Nicolás Achúcarro curtailed his promising career, but he still completed the clinicopathological study of the first American case of Alzheimer's disease. On returning to Spain, he studied glial cells, including rod cells. Rodríguez Lafora described progressive myoclonus epilepsy and completed experimental studies of corpus callosum lesions and clinical and neuropathology studies of senile dementia. He fled to Mexico at the end of the Spanish Civil War (1936-1939). Sanchís Banús, a sterling clinical neurologist, described the first cluster of Huntington's disease in Spain, and he and Río-Hortega joined efforts to determine that pallidal degeneration underlies rigidity in advanced stages of the disease. Just after the war, Alberca Llorente eruditely described inflammatory diseases of the neuraxis. Manuel Peraita studied "the neurology of hunger" with data collected during the siege of Madrid. Dionisio Nieto, like many exiled intellectuals, settled in Mexico DF, where he taught neurohistological methods and neuropsychiatry in the tradition of the Madrid School of Neurology.

Transition for patients with epilepsy due to metabolic and mitochondrial disorders

The transition of adolescents with refractory epilepsy to the care of adult neurologists can be challenging. For those patients with epilepsy due to mitochondrial disorders, Lafora disease, Unverricht-Lundborg disease, and GLUT1 deficiency syndrome, a successful transition can be even more problematic for both caregivers and neurologists. Many of these patients require dietary treatments (ketogenic and modified Atkins diets) for long-term management of their epilepsy. For these patients, coordinating transfer of their dietary management is necessary.

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.

Polyglucosan inclusions (Lafora bodies) in a gray-headed flying fox (Pteropus poliocephalus)

Polyglucosan bodies (Lafora bodies) were identified in a juvenile gray-headed flying fox (Pteropus poliocephalus) with neurological signs. The structures were only noted in the brain stem, and no associated degenerative changes were present. These structures have not been previously identified in any species in the order Chiroptera.

Deletions and missense mutations of EPM2A exacerbate unfolded protein response and apoptosis of neuronal cells induced by endoplasm reticulum stress

The majority of the Lafora's disease (LD) is caused by defect in the EPM2A gene, including missense and nonsense mutations and deletions. These defects mainly occur in the carbohydrate-binding domain, and how these mutations cause neuronal defects is under active investigation. Here, we report that the mutant proteins encoded by all missense mutations and most deletions tested are unstable, insoluble and ubiquitinated, and are accumulated in aggresome-like structures. The effect of apparent 'gain-of-function' mutations can be corrected by co-transfection of wild-type EPM2A cDNA, which is consistent with the recessive nature of these mutations in LD patients. In a neuronal cell line, these mutant aggregates exacerbate endoplasm reticulum (ER) stress and make the cells susceptible to the apoptosis induced by ER stressor, thapsigargin. The chemical chaperon, 4-phenylbutyrate, increased the mutant solubility, reduced the ER stress and dulled the sensitivity of mutant neuronal cells to apoptosis induced by thapsigargin and the mutant laforin proteins. The increased sensitivity to ER stress-induced apoptosis may contribute to LD pathogenesis.