Hyperphosphorylation of glucosyl C6 carbons and altered structure of glycogen in the neurodegenerative epilepsy Lafora disease.

Laforin or malin deficiency causes Lafora disease, characterized by altered glycogen metabolism and teenage-onset neurodegeneration with intractable and invariably fatal epilepsy. Plant starches possess small amounts of metabolically essential monophosphate esters. Glycogen contains similar phosphate amounts, which are thought to originate from a glycogen synthase error side reaction and therefore lack any specific function.

Progressive myoclonus epilepsy.

The progressive myoclonus epilepsies (PMEs) consist of a group of diseases with myoclonic seizures and progressive neurodegeneration, with onset in childhood and/or adolescence. Lafora disease is a neuronal glycogenosis in which normal glycogen is transformed into starch-like polyglucosans that accumulate in the neuronal somatodendritic compartment. It is caused by defects of two genes of yet unknown function, one encoding a glycogen phosphatase (laforin) and the other an ubiquitin E3 ligase (malin).

Glycogen hyperphosphorylation underlies lafora body formation.

Objective: Glycogen, the largest cytosolic macromolecule, acquires solubility, essential to its function, through extreme branching. Lafora bodies are aggregates of polyglucosan, a long, linear, poorly branched, and insoluble form of glycogen. Lafora bodies occupy vast numbers of neuronal dendrites and perikarya in Lafora disease in time-dependent fashion, leading to intractable and fatal progressive myoclonus epilepsy.

22-year-old girl with status epilepticus and progressive neurological symptoms.

A 22-year-old girl presented with convulsive status epilepticus and a previous history of recurrent seizures, myoclonus, ataxia and impaired cognitive functions. Neurological examination revealed rest and action-induced myoclonus, pyramidal signs and opposition hypertonia. Testing revealed severe metabolic acidosis, elevated transaminases and creatine kinase, and respiratory insufficiency.

The autosomal recessively inherited progressive myoclonus epilepsies and their genes.

Autosomal recessively inherited progressive myoclonus epilepsies (PMEs) include Lafora disease, Unverricht-Lundborg disease, the neuronal ceroid lipofuscinoses, type I sialidosis (cherry-red spot myoclonus), action myoclonus-renal failure syndrome, and type III Gaucher disease. Almost all the autosomal recessively inherited PMEs are lysosomal diseases, with the exception of Lafora disease in which neither the accumulating material nor the gene products are in lysosomes. Progress in identifying the causative defects of PME is near-complete.

ATP hydrolysis and pristinamycin IIA inhibition of the Staphylococcus aureus Vga(A), a dual ABC protein involved in streptogramin A resistance.

In Gram-positive bacteria, a large subfamily of dual ATP-binding cassette proteins confers acquired or intrinsic resistance to macrolide, lincosamide, and streptogramin antibiotics by a far from well understood mechanism. Here, we report the first biochemical characterization of one such protein, Vga(A), which is involved in streptogramin A (SgA) resistance among staphylococci. Vga(A) is composed of two nucleotide-binding domains (NBDs), separated by a charged linker, with a C-terminal extension and without identified transmembrane domains.

Typical progression of myoclonic epilepsy of the Lafora type: a case report.

Background: A 20-year-old woman presented to a specialist epilepsy center with a 3-year history of drug-resistant epileptic seizures, progressive myoclonus, ataxia, and cognitive decline.

Investigations: Neurological examination, neuropsychological testing, electrophysiological studies, skin biopsy, MRI, genetic testing, and autopsy.

Diagnosis: Lafora disease (EPM2), resulting from a homozygous missense mutation in EPM2B (NHLRC1; c205C>G; Pro69Ala).

Laforin is a glycogen phosphatase, deficiency of which leads to elevated phosphorylation of glycogen in vivo.

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.

Molecular characterization of laforin, a dual-specificity protein phosphatase implicated in Lafora disease.

Lafora disease is a progressive myoclonus epilepsy with an early fatal issue. Two genes were identified thus far, the mutations of which cause the disease. The first one, EPM2A, encodes the consensus sequence of a protein tyrosine phosphatase.