Quick GuideAutism Signs in Children: What Is Autism Spectrum Disorder?

In 2007, according to Individuals with Disabilities Education Act administrative counts, 5,912,586 children 6 through 21 years of age received services through 13 categories in public special education programs. "Specific learning disability" was the most frequent education category identified, followed by "speech and language impairment." Together, these two categories made up nearly 64% of all special education placements. The intellectual disability classification accounted for about 8% (487,854). Autism accounted for about 4% (256,863).

CDC's Metropolitan Atlanta Developmental Disabilities Surveillance Program (MADDSP) found the autism rate among 8-year-old children in 2000 to be 6.5 per 1,000. That's lower than the rate for intellectual disability/mental retardation (12.0 per 1,000) but higher than the rate for cerebral palsy (3.1 per 1,000), hearing loss (1.2 per 1,000), and vision impairment (1.2 per 1,000) found among children of the same age.

Mitochondria are tiny parts of almost every cell in your body. Mitochondria are like the power house of the cells. They turn sugar and oxygen into energy that the cells need to work. In mitochondrial diseases, the mitochondria cannot efficiently turn sugar and oxygen into energy, so the cells do not work the way they should.

There are many types of mitochondrial disease, and they can affect different parts of the body: the brain, kidneys, muscles, heart, eyes, ears, and others. Mitochondrial diseases can affect one part of the body or many parts. The effects can be mild or very serious.

Not everyone with a mitochondrial disease will show symptoms. However, among the mitochondrial diseases that tend to affect children, symptoms usually appear in the toddler and preschool years.