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Pyridoxine-dependent epilepsy


Other Names for this Disease

  • Pyridoxine dependency
  • Pyridoxine dependency with seizures
  • Vitamin B6-dependent seizures
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Overview

What is pyridoxine-dependent epilepsy?

What symptoms are associated with pyridoxine-dependent epilepsy?

What causes pyridoxine-dependent epilepsy?

How might pyridoxine-dependent epilepsy be treated?

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

References
  1. Pyridoxine-dependent epilepsy. Genetics Home Reference (GHR). 2013; http://ghr.nlm.nih.gov/condition=pyridoxinedependentepilepsy. Accessed 7/23/2013.
  2. Gospe SM. Pyridoxine-Dependent Seizures. GeneReviews. 2012; http://www.ncbi.nlm.nih.gov/books/NBK1486/. Accessed 7/23/2013.
  3. van Karnebeek CD et al. Lysine restricted diet for pyridoxine-dependent epilepsy: first evidence and future trials. Mol Genet Metab. 2012 Nov;107(3):335-44. .


Other Names for this Disease
  • Pyridoxine dependency
  • Pyridoxine dependency with seizures
  • Vitamin B6-dependent seizures
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.