Autism for some children may be related to defects in the mitochondria, the tiny bean-shaped powerhouses of cells where both energy production and the DNA may be impaired, say scientists in a medical investigation released Wednesday.
Reporting in the Journal of the American Medical Association, researchers have found that children with autism have impairments in energy production and deletions in genes contained within the mitochondria (pronounced my-toe-KON-dree-ah), miniature power plants in cells where nutrients from food are converted into chemical energy. The heart and brain are chock full of these oblong energy producers, and defects in them have long been associated with other serious medical conditions including Parkinson's and Alzheimer's diseases, experts say.
The lead researcher, Cecilia Giulivi, said her research was aimed at developing a way to test for autism. "We want to develop a screening [test] for a biomarker," she said.
Giulivi, a researcher at the University of California, Davis, said her small study of 10 children between the ages of 2 and 5 with autism and 10 children of the same ages without the condition shows that energy production in the mitochondria of those with autism is only one-third as effective.
"What we don't know yet is whether the mitochondrial dysfunction is a cause or a consequence of the condition," she said.
For years, parents on Long Island and elsewhere have argued their children diagnosed as having autism actually are affected by mitochondrial defects but the scientific work to support their claims have been scarce. Parents have based their contention on studies that have shown lower levels of energy production in the brain may account for some of the hallmarks of the condition, mainly the social and cognitive deficits. Some autistic children fail to interact with siblings and parents; others fail to talk.
"It always takes the medical and scientific community a long time to catch up with what parents are saying," said Evelyn Ain, an advocate for children with autism and the mother of a son with an autism-spectrum disorder.
Dr. David Tegay, a molecular geneticist at New York College of Osteopathic Medicine in Old Westbury, said the new research is intriguing because other serious disorders affecting children also emanate in mitochondria.
But Dr. Eli Hatchwell, a former professor at Stony Brook and now the founder of a new biotechnology company, Population Diagnostics, based in Melville and Oxford, England, says the findings are intriguing but not definitive.
"I have said it before and I will say it again: There is no single cause of autism," Hatchwell said.
Hatchwell's company, which is pursuing a diagnostic test for autism, said ultimately the numerous genes linked to autism will be found in the nucleus of cells, not the mitochondria where a scant few genes are inherited only from the mother.
Giulivi said the intent of her study was not to look for inheritance patterns but to find how the mitochondria and mitochondrial genes differed between children with autism and those without the condition. The mitochondria have their own form of DNA, which is circular and separate from the helical DNA tucked in the nucleus of virtually every cell and carries the blueprint for all human inheritance and functions. Mitochondrial DNA carries instructions for energy production.