Autism Risk Factors and Characteristics - Siblings, Fragile X, Intellectual Disability, Tuberous Sclerosis, Apraxia

Risk Factors and Characteristics @ Centers for Disease Control and Prevention

Risk Factors and Characteristics

  • Studies have shown that among identical twins, if one child has an ASD, then the other will be affected about 60-96% of the time. In non-identical twins, if one child has an ASD, then the other is affected about 0-24% of the time. [1]
  • Parents who have a child with an ASD have a 2%–8% chance of having a second child who is also affected. [1]
  • It is estimated that about 10% of children with an ASD have an identifiable genetic, neurologic or metabolic disorder, such as fragile X or Down syndrome. As we learn more about genetics, the number of children with an ASD and an identifiable genetic condition will likely increase. [Read summaryExternal Web Site Icon] [Read summaryExternal Web Site Icon]
  • A report published by CDC in 2009, shows that 30-51% (41% on average) of the children who had an ASD also had an Intellectual Disability (intelligence quotient <=70). [Read article]
  • Studies show that 5% of people with an ASD are affected by fragile X and 10% to 15% of those with fragile X show autistic traits. [Read summaryExternal Web Site Icon]
  • One to four percent of people with ASD also have tuberous sclerosis. [Read summaryExternal Web Site Icon]
  • About 40% of children with an ASD do not talk at all. Another 25%–30% of children with autism have some words at 12 to 18 months of age and then lose them.  Others may speak, but not until later in childhood. [2]