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What is mitochondria disease? What does it have to do with autism, and are there treatments?

November 18, 2011 22 comments

This week’s “Got Questions?” answer comes from Deepa Menon, MD, assistant medical director of the Center for Autism and Related Disorders, at Baltimore’s Kennedy Krieger Institute—an Autism Speaks Autism Treatment Network (ATN) site. Her research interests include metabolic and mitochondrial disorders and their association with autism.

Mitochondria are cell structures, or “organelles,” whose primary function is to supply a cell with energy. In essence, they turn sugar and fatty acids from food into the energy-carrying molecule adenosine triphosphate (ATP).

Virtually every cell in the body depends on ATP and mitochondria for energy. As a result, mitochondrial disorders can produce a wide variety of symptoms. The most common involve body systems that use a lot of energy. Muscles are a classic example, and mitochondrial dysfunction often produces muscle weakness and fatigue. When mitochondrial dysfunction affects the gastrointestinal system, symptoms can include constipation or diarrhea. When it affects the immune system, it can lead to frequent infections. Mitochondrial disorders can likewise cause failure to grow, kidney dysfunction and a many other medical problems.

The brain is another energy-demanding system. Here, mitochondrial dysfunction can produce such symptoms as developmental delay, hearing problems and seizures.

Over the last decade, there has been great interest in the possibility that mitochondrial disorders may underlie some of the symptoms of autism spectrum disorder (ASD). Currently we believe that around 5 to 10 percent of children with autism have mitochondrial dysfunction as the underlying cause of their symptoms.

Research suggests that many children diagnosed with autism and underlying mitochondrial dysfunction experienced regression following a simple childhood illness (ear infection, common cold, etc.) or other cause of fever or inflammation. Regression refers to a loss of developmental skills such as language or motor abilities. It may be accompanied by other symptoms of mitochondrial disorder such as fatigue, gastrointestinal distress, seizures and/or motor delays.

Laboratory testing of blood samples and urine show that many of these children (with ASD and mitochondrial dysfunction) have abnormally high  levels of certain amino acids and cellular waste products. This suggests that their cells are generating energy inefficiently with an excess of damaging byproducts.

When a child is diagnosed with ASD and mitochondrial dysfunction, treatment goals include a bolstering mitochondrial activity and protecting the mitochondria from further damage. Parents and affected individuals may be counseled to avoid (as much as possible) situations that stress mitochondria. Examples of these stresses include going for long periods between meals (prolonged fasting), infections that produce fevers, inflammation associated with dietary sensitivities and certain medications such as the antipsychotic haloperidol (Haldol), which is known to impair mitochondrial function.

Supportive treatment can include a prescription nutrient mixture containing the protein L-carnitine and the B-vitamin pantothenate, which is thought to bolster mitochondrial activity. This prescription mixture usually contains additional nutrients such as thiamine, nicotinamide, lipoic acid, and vitamins C and E. Coenzyme Q10 may be added for those who show low levels of CoQ10 on testing.

[Editor’s note: Autism Speaks continues to support research into the association of mitochondrial disease and autism and their effective treatments. For more information on these and other funded studies, please explore our Grant Search portal, here.]

Have a question? Email us at gotquestions@autismspeaks.org. For more news and perspective, please visit the Autism Speaks science page.

What is mitochondrial disease? How often does it occur in individuals with ASD? Are their effective treatments?

November 9, 2010 8 comments

“Got Questions?” is a new weekly feature on our blog to address the desire for scientific understanding in our community.  We received over 3000 responses when we asked what science questions were on your mind. We answered a few here and the Autism Speaks Science staff will address the other themes we received in this weekly post.

Cell with LabelsMitochondrial disease is caused by an error in the functioning of mitochondria, which are essential energy-producing compartments of nearly every cell in the body. Certain mutations can cause the mitochondria to function inefficiently. These mutations can be within the mitochondria itself, with its own small circle of DNA, or within the nucleus where the rest of the cell’s DNA resides. Over 1500 genes carry some part of the recipe for the optimal functioning of mitochondria. This means that there are many ways for mitochondria to function imperfectly but there are also complex means available to mask a deficit by altering some of the other protein interactions.

Mitochondria are responsible for the process of oxidative phosphorylation that turns nutrients into energy through a series of stages involving complexes of enzymes. A break at any particular stage results in an atypical balance of metabolites in affected body tissues and fluids.

Most people consider mitochondrial disease to be one of a growing number of disorders caused by a defined set of mutations and presenting with a set of characteristics that typically involve three or more organ systems. However, mitochondrial disorders are often diagnosed when no mutation is found despite observations of metabolic signatures of mitochondrial dysfunction. The symptoms may also be more mild.

We do not have a firm estimate of mitochondrial disease in ASD. However, if we use the broader definition of mitochondrial disorder then according to a population-based study in Portugal, there may be as many as 4% of the ASD population affected. Autism Speaks’ research is addressing this and related questions through a grant to Cecilia Giulivi, Ph.D. at UC Davis and also through a collaborative research project at UC Irvine and UC San Diego.

There is currently no cure for mitochondrial disease or disorder. There are, however, treatments and practices that can improve the quality of life and slow the progression of the disease. The most effective treatments are for specific symptoms that tend to accompany mitochondrial dysfunction such as seizures treated with anti-convulsants. Regular exercise, a healthy diet, stress and extreme temperature avoidance are among the common recommendations. Some dietary and supplement regimes have anecdotal support but there is a need for empirical studies to test the efficacy of these therapies.

For more information, please visit the United Mitochondrial Disease Foundation (UMDF) website. Also, read our report on a joint Autism Speaks’ supported symposium at the annual UMDF meeting.

Fever Plus Mitochondrial Disease Could Be Risk Factors for Autistic Regression

March 11, 2010 8 comments
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