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Unverricht-Lundborg Disease

Last updated May 2, 2018

Approved by: Maulik P. Purohit MD, MPH

Unverricht-Lundborg Disease is an inherited form of progressive myoclonus epilepsy that is characterized by episodes of involuntary muscle jerking or twitching (myoclonus) that increase in frequency and severity over time.


What are the other Names for this Condition? (Also known as/Synonyms)

  • Baltic Myoclonic Epilepsy
  • Myoclonus Progressive Epilepsy of Unverricht and Lundborg
  • Progressive Myoclonus Epilepsy 1

What is Unverricht-Lundborg Disease? (Definition/Background Information)

  • Unverricht-Lundborg Disease is an inherited form of progressive myoclonus epilepsy that is characterized by episodes of involuntary muscle jerking or twitching (myoclonus) that increase in frequency and severity over time
  • Unverricht-Lundborg Disease is caused by mutation in the CSTB gene. It is inherited in an autosomal recessive pattern
  • Episodes of myoclonus may be brought on by physical exertion, stress, light, or other stimuli
  • Affected individuals usually begin showing signs and symptoms of the disorder between the ages of 6 and 15. Over time, the myoclonic episodes may become severe enough to interfere with walking and other everyday activities
  • Other features include seizures involving loss of consciousness, muscle rigidity, and convulsions (tonic-clonic or grand mal seizures). Like the myoclonic episodes, these may increase in frequency over several years but may be controlled with treatment
  • After several years of progression, the frequency of seizures may stabilize or decrease

(Source: Unverricht-Lundborg Disease; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Unverricht-Lundborg Disease? (Age and Sex Distribution)

  • Unverricht-Lundborg Disease is a rare congenital disorder. The exact prevalence of this disorder is not known
  • The manifestation of symptoms typically begins in childhood, between ages 6 and 15 years
  • Both males and females may be affected
  • Worldwide, individuals of all racial and ethnic groups may be affected. However, the disorder is more common in Finland, where it occurs at a frequency of approximately 1:25,000

What are the Risk Factors for Unverricht-Lundborg Disease? (Predisposing Factors)

  • A positive family history may be an important risk factor, since Unverricht-Lundborg Disease can be inherited

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Unverricht-Lundborg Disease? (Etiology)

  • Unverricht-Lundborg Disease is a genetic disorder that is transmitted in an autosomal recessive manner
  • It is reportedly caused by CSTB gene mutations

(Source: Unverricht-Lundborg Disease; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Autosomal recessive pattern of inheritance: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Unverricht-Lundborg Disease?

The signs and symptoms of Unverricht-Lundborg Disease may include:

Very frequently present symptoms in 80-99% of the cases:

  • EEG with polyspike wave complexes
  • Limb ataxia
  • Morning myoclonic jerks

Frequently present symptoms in 30-79% of the cases:

  • Dysarthria
  • Intention tremor

In addition, the following signs and symptoms may be present:

  • Absence seizures
  • Ataxia
  • Cutaneous photosensitivity
  • Dementia
  • Generalized tonic-clonic seizures
  • Intellectual disability
  • Mental deterioration
  • Myoclonus

Episodes of myoclonus may be brought on by physical exertion, stress, light, or other stimuli.

(Source: Unverricht-Lundborg Disease; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Unverricht-Lundborg Disease Diagnosed?

Unverricht-Lundborg Disease is diagnosed on the basis of the following information:

  • Complete physical examination
  • Thorough medical history evaluation
  • Assessment of signs and symptoms
  • Laboratory tests
  • Imaging studies
  • Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Unverricht-Lundborg Disease?

The complications of Unverricht-Lundborg Disease may include:

  • Difficulty with movement
  • Progressive worsening of symptoms, such that day-to-day activities are affected
  • Increased risk of falls and injuries due to convulsions

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Unverricht-Lundborg Disease Treated?

There is no cure for Unverricht-Lundborg Disease, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that develop.

How can Unverricht-Lundborg Disease be Prevented?

Unverricht-Lundborg Disease may not be preventable, since it is a genetic disorder.

  • Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy), if available, may help in understanding the risks better during pregnancy
  • If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
  • Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
  • Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Unverricht-Lundborg Disease? (Outcomes/Resolutions)

  • The prognosis of Unverricht-Lundborg Disease is dependent upon the severity of the signs and symptoms and associated complications, if any
  • The convulsions may be controlled with medication. Over time, the frequency of episodes may stabilize or decrease
  • Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Unverricht-Lundborg Disease:

Unverricht-Lundborg Disease is also known by the following names:

  • EPM1 (Epilepsy, Progressive Myoclonus, 1)
  • Myoclonic Epilepsy of Unverricht and Lundborg
  • Myoclonic Epilepsy, Baltic type
  • Progressive Myoclonic Epilepsy Type 1

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/

What are some Useful Resources for Additional Information?


References and Information Sources used for the Article:


Helpful Peer-Reviewed Medical Articles:


Reviewed and Approved by a member of the DoveMed Editorial Board
First uploaded: May 2, 2018
Last updated: May 2, 2018