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Genetic and Rare Diseases Information Center (GARD)

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Pyridoxine-dependent epilepsy


Other Names for this Disease
  • Pyridoxine dependency
  • Pyridoxine dependency with seizures
  • Vitamin B6-dependent seizures
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Your Question

My daughter was diagnosed with pyridoxine-dependent epilepsy at birth. Her symptoms were controlled until a few years ago when she began to have muscle stiffness in the hands and legs, partial seizures, and loss of her voice. Her seizures now occur almost daily and are quite violent. Her doctors believe that her seizure activity may now be the result of psychogenic nonepileptic seizures (PNES). Is this a common occurrence in adults with pyridoxine-dependent epilepsy?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What is pyridoxine-dependent epilepsy?

Pyridoxine-dependent epilepsy is a condition that involves seizures beginning in infancy or, in some cases, before birth. Those affected typically experience prolonged seizures lasting several minutes (status epilepticus). These seizures involve muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures). Anticonvulsant drugs, which are usually given to control seizures, are ineffective in people with pyridoxine-dependent epilepsy. Instead, people with this type of seizure are medically treated with large daily doses of pyridoxine (a type of vitamin B6 found in food). Mutations in the ALDH7A1 gene cause pyridoxine-dependent epilepsy. This gene is inherited in an autosomal recessive fashion.[1]
Last updated: 7/23/2013

What symptoms are associated with pyridoxine-dependent epilepsy?

Those affected by pyridoxine-dependent epilepsy typically experience prolonged seizures lasting several minutes (status epilepticus). These seizures involve muscle rigidity, convulsions, and loss of consciousness (tonic-clonic seizures). Additional features of pyridoxine-dependent epilepsy include low body temperature (hypothermia), poor muscle tone (dystonia) soon after birth, and irritability before a seizure episode. In rare instances, children with this condition do not have seizures until they are 1 to 3 years old.  If left untreated, people with this condition can develop severe brain dysfunction (encephalopathy). Even though seizures can be controlled with pyridoxine, neurological problems such as developmental delay and learning disorders may still occur.[1]
Last updated: 7/23/2013

What causes pyridoxine-dependent epilepsy?

Mutations in the ALDH7A1 gene cause pyridoxine-dependent epilepsy. This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.[1]

The ALDH7A1 gene provides instructions for making an enzyme called α-aminoadipic semialdehyde (α-AASA) dehydrogenase, also known as antiquitin. This enzyme is involved in the breakdown of the protein building block (amino acid) lysine in the brain.[1]

When antiquitin is deficient, a molecule that interferes with vitamin B6 function builds up in various tissues. Pyridoxine plays a role in many processes in the body, such as the breakdown of amino acids and the productions of chemicals that transmit signals in the brain (neurotransmitters). It is unclear how a lack of pyridoxine causes the seizures that are characteristic of this condition.[1]

Some individuals with pyridoxine-dependent epilepsy do not have identified mutations in the ALDH7A1 gene. In these cases, the cause of the condition is unknown.[1]

Last updated: 7/23/2013

How might pyridoxine-dependent epilepsy be treated?

Anticonvulsant drugs, which are usually given to control seizures, are ineffective in people with pyridoxine-dependent epilepsy. Instead, people with this type of seizure are medically treated with large daily doses of pyridoxine (a type of vitamin B6 found in food).[1][2] Recent studies have focused on using a lysine-restricted diet in addition to pyridoxine. Preliminary results suggest that this treatment has the potential to help control seizures and improve developmental outcomes in children with pyridoxine-dependent epilepsy.[3]
Last updated: 7/23/2013

What are psychogenic nonepileptic seizures?

Nonepileptic seizures are behavioral events that resemble epileptic seizures but are not caused by electrical disruptions of the cerebral cortex. Psychogenic nonepileptic seizures result from stressful psychological conflicts or major emotional trauma, often stemming from sexual and/or physical abuse, current or in the past, especially in childhood. Other causes include major life events such as death or divorce.[4]

You can read more about this type of seizure at the following link from the Epilepsy Foundation. For additional information, contact the Women and Epilepsy Initiative of the Epilepsy Foundation at (800) 332-4050.
Last updated: 5/26/2009

Are you aware of any other individuals with pyridoxine-dependent epilepsy who have developed psychogenic nonepileptic seizures in adulthood?

After an extensive search of the resources available to us, we have not been able to identify any reports which discuss individuals with pyridoxine-dependent epilepsy who have developed psychogenic nonepileptic seizures in adulthood. 

You may wish to contact the following organizations which deal specifically with epilepsy to see if they are aware of any such cases. These groups may also be able to recommend a specialist who can assist your daughter in control of her symptoms.

Epilepsy Foundation
8301 Professional Place
East Landover, MD 20785-2238
Toll-free: 800-EFA-1000 (800-332-1000)
Phone: 301-459-3700
Fax: 301-577-4941
Email: webmaster@efa.org  
Web: www.efa.org

American Epilepsy Society
342 North Main Street
West Hartford CT 06117-2507
Phone: 860-586-7505
Fax: 860-586-7550
Email: info@aesnet.org  
Web: www.aesnet.org

 

Last updated: 5/26/2009

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