Lafora progressive myoclonus epilepsy
Lafora progressive myoclonus epilepsy is a brain disorder characterized by recurrent seizures and a progressive decline in intellectual function that typically begins in late childhood or adolescence.
Overview
Lafora progressive myoclonus epilepsy is a brain disorder that worsens over time. The condition is defined by myoclonus—sudden, involuntary muscle jerking or twitching—and various types of seizures. As the disease progresses, individuals experience a decline in intellectual function, eventually leading to dementia. By their mid-twenties, affected individuals typically lose the ability to perform daily activities and require comprehensive care. Survival is generally limited to 10 years after the onset of symptoms.
Symptoms
- Myoclonus: Sudden muscle jerking that can affect part or all of the body; often triggered by rest, motion, excitement, or flashing lights.
- Seizures: Includes generalized tonic-clonic (grand mal) seizures, occipital seizures (causing temporary blindness and hallucinations), and potentially status epilepticus (continuous, life-threatening seizure activity).
- Cognitive and Behavioral Changes: Early signs include confusion, depression, behavioral changes, and speech difficulties (dysarthria).
- Dementia: A continued loss of memory, judgment, and thought processes.
Causes
The disorder is caused by mutations in the EPM2A or NHLRC1 genes, which provide instructions for producing the proteins laforin and malin. These proteins are essential for the survival of neurons and help regulate the production of glycogen.
In affected individuals, an abnormal form of glycogen builds up into clumps known as Lafora bodies. These clumps cannot be broken down for fuel and instead accumulate within cells, causing damage to neurons. While Lafora bodies are found in many tissues, the symptoms of the disease are limited to the nervous system.
Inheritance
This condition is inherited in an autosomal recessive pattern. This means both copies of the gene in each cell must have mutations for the disorder to occur. Parents of an affected individual each carry one copy of the mutated gene but typically do not exhibit symptoms.