A vaccine preservative may have contributed to a case of autism, the federal government conceded after years of denying a link.
 
In its written concession statement, the government said the child had a pre-existing mitochondria disorder that was "aggravated" by her shots, resulting in an autism spectrum disorder (ASD) diagnosis.
 
Mitochondria are the powerhouses of the cell, converting oxygen and food into energy for every life function.
 
The news site Huffington Post at www.huffingtonpost.com reported in November that federal officials had confirmed the link to thimerosal Nov. 9.
The government then sealed records of its statement, the Web site reported.
 
"The vaccinations received on July 19, 2000, significantly aggravated an underlying mitochondrial disorder, which predisposed [the child] to deficits in cellular energy metabolism, and manifested as a regressive encephalopathy [brain disease] with features of ASD," the concession obtained by Huffington Post states.
 
Mitochondrial disorders are rare, affecting one in every 2,000 to 4,000 people, according to the United Mitochondrial Disease Foundation.
Symptoms include lethargy, poor coordination and problems eating or digesting food.
 
However, the number of children with autism affected by mitochondrial disorders is around one in five.
 
With 4,900 thimerosal cases pending in the federal courts, a distinct connection among thimerosal, mitochondrial disorders and autism would have far-reaching implications.
 
Most vaccines today do not use thimerosal as a preservative, according to a survey by the Johns Hopkins Bloomberg School of Public Health in Baltimore City.
 
The exceptions include large-batch adult flu vaccines made by some manufacturers.
 
Autism spectrum disorders are a group of developmental disabilities marked by impaired social interaction and communication and the presence of unusual behaviors and interests, according to the Centers for Disease Control and Prevention.
 
Many people with ASDs also have unusual ways of learning, paying attention or reacting to different sensations.
 
In about 10 percent of cases, genetics are a factor, said Dr. Harvey Singer, director of pediatric neurology at Hopkins Children's Hospital in Baltimore City, but the rest remain a mystery.