Juvenile myoclonic epilepsy

What causes juvenile myoclonic epilepsy?

The exact cause of juvenile myoclonic epilepsy remains unknown. It is not associated with conditions such as head trauma, brain tumor, or encephalitis.

Family history and genetic factors play a strong role in the risk for juvenile myoclonic epilepsy. About one third of affected people have a relative with epileptic seizures, and in several families, specific genetic mutations have been found. Mutations in the GABRA1 and EFHC1 genes, and other genes, not yet identified, can cause or may increase susceptibility to juvenile myoclonic epilepsy.

The GABRA1 gene provides instructions for making a protein involved with the influx of chloride ions crossing the cell membrane. The influx of chloride ions creates an environment in the cell that inhibits signaling between nerve cells (neurons) and prevents the brain from being overloaded with too many signals. Mutations in the GABRA1 gene lead to overstimulation of neurons in the brain, and triggers the abnormal brain activity associated with seizures.

Mutations in the EFHC1 gene have been associated with juvenile myoclonic epilepsy in a small number of people. The EFHC1 gene provides instructions for making a protein that also plays a role in neuron activity, although its function is not completely understood, but that may also lead to overstimulation of neurons and trigger seizures.

In people with juvenile myoclonic epilepsy, symptoms can be brought on by:

  • Sleep deprivation
  • Psychological stress
  • Alcohol and drug use
  • Noncompliance of medication
  • Flickering lights such as strobe lights
  • Menses
  • Time of day - usually mornings

Last updated on 05-01-20

How is juvenile myoclonic epilepsy inherited?

While juvenile myoclonic epilepsy is an inherited disorder (about a third of patients have a family history of epilepsy), the exact mode of inheritance is not clear. Studies have indicated that inheritance is autosomal dominant, however, it has incomplete penetrance, which means that some people who inherit the gene or genes associated with juvenile myoclonic epilepsy do not develop symptoms.

Due to the complex nature of inheritance with this condition, it is advised to consult a genetics professional, who can provide additional information about diagnosis, natural history, treatment, mode of inheritance, and genetic risks to other family members. To find a genetics clinic, we recommend that you contact your primary doctor for a referral. Click here to learn more about genetic consultations and here to find a genetics clinic.

Last updated on 05-01-20

What is the long-term outlook for people with juvenile myoclonic epilepsy?

Seizures are usually well controlled with seizure medications and studies show that seizures tend to improve after the fourth decade of life. Even when a person is seizure-free, seizure medication is typically continued due to a high risk for recurrence (particularly in those with more severe forms). For the majority of people, lifelong treatment is necessary.

Last updated on 05-01-20

How might juvenile myoclonic epilepsy be treated?

Avoiding precipitating events such as alcohol use and sleep deprivation may be useful. However, medical therapy with anti-convulsants is typically needed and well tolerated. The majority of patients can be well-controlled on a single drug, most commonly valproic acid. Other medications that might be used separately or in combination include lamotrigine, levetiracetam, clonazepam, and topiramate.

More details about the medications used to treat juvenile myoclonic epilepsy are available through Medscape Reference and the Epilepsy Foundation.

Last updated on 05-01-20

Name: Epilepsy Foundation 8301 Professional Place East Suite 230
Landover, MD, 20785, United States
Phone: +1-301-459-3700 Toll Free: 800-332-1000 (24/7 Helpline) Fax : +1-301-577-2684 Email: contactus@efa.org Url: https://www.epilepsy.com/ en Español 1-866-748-8008

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The RareGuru disease database is regularly updated using data generously provided by GARD, the United States Genetic and Rare Disease Information Center.

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