Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by impaired social interaction and communication, as well as isolated interests and repetitive or stereotyped behaviors . ASDs pose a significant burden to affected individuals, their families and society. This burden comes both from the debilitating and lifelong nature of ASDs and from their prevalence. It is now estimated that about one out of every 166 children is affected with ASD . Most cases are idiopathic, although there are many uncommon or rare genetic and metabolic causes of autism that are increasingly recognized –.
In 1998, Lombard postulated mitochondrial dysfunction as a cause of autism . Prior and subsequent case reports provided biochemical data indicating perturbation of mitochondrial energy metabolism in some individuals with ASD –, including mtDNA mutations in several , , . Recently, Oliveira and colleagues published a population-based survey of school-age children with ASD. They found that 7% of those who were fully tested met criteria for definite mitochondrial respiratory chain disorders and were also clinically indistinguishable from other children with ASD . This work is notable because it suggests that mitochondrial disorders of energy production may be present in a substantial percentage of children with ASD. To better describe the clinical spectrum of children with ‘mitochondrial autism’, we undertook a chart review of the biochemical, genetic, and histopathological findings in 25 patients with ASD who had unequivocal evidence of a disorder of oxidative phosphorylation.