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Mitochondrial Encephalopathies: Potential Relationships to Autism?

July 08, 2008


NIH Sponsored Meeting Bridges Autism and Mitochondrial Disease Research

On Sunday, June 29, a panel of 15 experts in the fields of mitochondrial disease and autism convened in Indianapolis to discuss the co-occurrence of these two disorders. The Hannah Poling case has brought this issue to the public and into focus as a priority for researchers and clinicians. The meeting began with an overview of mitochondrial disease and dysfunction, and then progressed to discuss what mitochondrial dysfunction looks like in children with autism. The discussion then shifted to diagnostic testing, what we still need to learn from research in this area, and finally what is known about potential triggers that disturb mitochondrial function, especially in a vulnerable population.

Diagnosing mitochondrial disease or dysfunction is complex owing in large part to heteroplasmy -- not all mitochondria are affected simultaneously by the disorder and the proportion of affected mitochondria vary in different tissues sampled and also change over time, not necessarily for the worse. Clinical experts on the panel noted that asymptomatic or very mild mitochondrial dysfunction might go undetected for years, even by seasoned clinicians. Detection of one of the known genetic mutations is considered one of the best ways to obtain a certain diagnosis; however there is currently no way to definitively rule out a diagnosis of mitochondrial dysfunction. Laboratory testing of urinary organic acids and lactate/pyruvate levels are first steps that may indicate whether more invasive tests are warranted.

The researchers who are experts in mitochondrial disease and have seen patients with autism in their practice made two especially useful points. First, when mitochondrial dysfunction is seen in individuals with autism, it appears to be much milder than the types of mitochondrial disease often seen in a traditional mitochondrial medicine practice. Some patients with autism can potentially benefit from the same types of therapies offered to traditional patients. Second, psychiatric conditions, including pervasive developmental disorders and depression, appear to occur more frequently than expected in families with certain types of mitochondrial disease. These hints can help guide future research in this area.

The most important outcome of this meeting was the initiation of a dialog between researchers in autism and mitochondrial disease, increasing future collaborative research in this area. The promise of further collaboration was encouraging to the approximately 50 audience members who were scientists or advocates interested in seeing more research at the interface of these two complex disorders. The meeting was sponsored by NIH as a special symposium held at the close of the annual meeting of the United Mitochondrial Disease foundation (www.umdf.org). Two members from the Autism Speaks science team, Leanne Chukoskie, Ph.D. and Sophia Colamarino, Ph.D., attended the meeting.

Read an Autism Tissue Program (ATP - an Autism Speaks resource) quarterly recap article about recently published studies addressing the impact of mitochondrial dysfunction in autism here.