This condition is characterized by the recurrent seizures commonly the myoclonic seizures which cause the rapid uncontrolled jerky movements of the muscles. In addition, the affected individual can also experience generalized tonic-clonic seizures which cause convulsions, muscle rigidity and loss of consciousness. The seizures typically occur early in the morning after waking. Myoclonic epilepsy juvenile can begin between the ages of 12 and 18.
Causes
Several genetic mutations are associated with the development of this condition, some of which are recognized and others still unidentified. The most commonly identified genetic mutations occur in the genes GABRA1 and EFHC1. The GABRA1 gene is responsible for the production of the alpha-1 subunit of the receptor protein. This receptor protein functions as a channel allowing the negatively charged chlorine atoms to cross the cell membrane. This genetic mutation results in the altered production of the alpha-1 subunit and reduced quantity of the receptor protein. As the result, it can cause the overstimulation of certain neurons in the brain which can trigger the abnormal activity of the brain associated with the seizures. The mutation in the EFHC1gene produces a protein that is essential for the neuron activity. The EFHC1 protein is important for the regulation of the balance of calcium ions inside the cells. The genetic mutation causes the reduced function of the EFHC1 protein which can increase the number of neurons and disrupts the calcium balance. It can also cause the overstimulation of neurons which can trigger the seizures. The GABRA1 genetic mutation is inherited in an autosomal dominant pattern meaning a single copy of the defective gene in each cell can cause the condition. The inheritance pattern for the EFHC1 gene is not known. In several of the cases, this condition can occur with no family history of this disorder.
Symptoms
The characteristic feature of this condition is the myoclonic jerks on awakening from sleep which appears as shock-like, irregular movements of both arms which may be restricted to the fingers. In around 20% of the cases, it affects a single side of the body. Most of the affected individuals may experience generalized tonic-clonic seizures and absence seizures in around 1 out of 3 people. The seizures particularly occur within 30 minutes to an hour after awakening. Seizures can also be triggered by sleep deprivation, stress and fatigue particularly after excessive alcohol consumption.
Diagnosis
The EEG is the initial step towards diagnosing the juvenile myoclonic epilepsy. In around 30% of the cases, they may exhibit abnormal EEG response to flickering lights. In the case a normal EEG is obtained, an EEG capturing sleep and wakefulness should be conducted to ensure the diagnosis has been carefully assessed.
Treatment
The treatment includes anti-epileptic medications and in some cases, the lifestyle changes can also help control seizures. It is also important to avoid triggering factors such as sleep deprivation, getting enough rest and to avoid drinking alcohol.
References
https://ghr.nlm.nih.gov/condition/juvenile-myoclonic-epilepsy#inheritance
http://www.epilepsy.com/learn/types-epilepsy-syndromes/juvenile-myoclonic-epilepsy