HIBCH deficiency

What causes HIBCH deficiency?

HIBCH deficiency is caused by mutations in the HIBCH gene. The deficiency results in a block of the breakdown (catabolism) of valine. This leads to a build up of toxic valine metabolites within the mitochondria in the body's cells. Valine is an essential amino acid, which means that it cannot be made by the body, but instead must be obtained from diet.

Valine catabolism involves several steps with different enzymes acting in each step. The 3-hydroxy-isobutyryl-CoA hydrolase (HIBCH) is a mitochondrial enzyme that acts in the 5th step, therefore all the substances that are produced before this step build-up. One of the metabolites, known as methacrylyl-CoA, can react with other mitochondrial enzymes and disrupt their activities. As a result, **** patients with HIBCH deficiency have features similar to Leigh disease and other mitochondrial disorders.

HIBCH deficiency is considered an organic acidemia. Organic acidemias are so named because they disrupt amino acid metabolism. This causes an increase in organic acid levels. In HIBCH deficiency we see an increase in lactic acid.

HIBCH deficiency can also be considered a mitochondrial disease, because it disrupts mitochondrial enzymes.

The involvement of the globi pallidi in HIBCH deficiency is one of the main features of the disease. The globi pallidi is part of the basal ganglia in the brain. The reason that the globi pallidi is affected may be due to a failure in providing energy to the brain which results in the early death of brain cells. This finding is also a feature of other mitochondrial diseases (including Leigh syndrome) and of other organic acidemias.

HIBCH is also involved in a second metabolic pathway. This pathway is related to propionate metabolism. Propionate is a substance produced by the break down of some aminoacids. However, the HIBCH gene mutations do not appear to result in adverse symptoms related to this pathway.

Last updated on 05-01-20

How might HIBCH deficiency be treated?

Treatment of HIBCH deficiency involves frequent carbohydrate-rich meals, along with coenzyme Q10, vitamin C, and vitamin E supplementation.

People with HIBCH deficiency may also benefit from a low-valine diet with carnitine and N-acetyl- cysteine supplementation.

Prompt, supportive, treatment during periods of physical stress and viral illness is vital. This may involve frequent infusions of bicarbonate, plus additional supports as required.

We strongly recommend that these and other treatment options be carefully reviewed with a healthcare provider.

Last updated on 05-01-20

Name: Metabolic Support UK 5 Hilliards Court Sandpiper Way
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Phone: 0845 241 2173 Toll Free: 0800 652 3181 Email: https://www.metabolicsupportuk.org/contact-us Url: https://www.metabolicsupportuk.org
Name: United Mitochondrial Disease Foundation 8085 Saltsburg Road, Suite 201
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Phone: 716-907-4349 Fax : 716-845-1047 Email: contact@mitoresearch.org Url: http://www.mitoresearch.org
Name: Organic Acidemia Association 9040 Duluth Street
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Phone: 763-559-1797 Fax : 866-539-4060 Email: mkstagni@gmail.com Url: http://www.oaanews.org/
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Phone: 1-888-MITO-411 (648-6411) for support line Toll Free: 1-888-648-6228 Email: info@mitoaction.org Url: https://www.mitoaction.org/
Name: Pediatric Brain Foundation 2144 E. Republic Rd. Building B, Suite 202
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Phone: 417-887-4242 Email: info@pediatricbrainfoundation.org Url: http://www.pediatricbrainfoundation.org/

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