What is the most common form of inherited intellectual disability associated with autism?

Fragile X disorder is recognized as the most common form of inherited intellectual disability that is also associated with autism. This genetic condition results from a mutation in the FMR1 gene on the X chromosome, leading to a range of developmental challenges, including intellectual disability and features of autism spectrum disorder.

Individuals with Fragile X often display behavioral characteristics such as social anxiety, hyperactivity, and challenges with communication, which overlap significantly with the manifestations of autism. The prevalence of Fragile X among individuals with autism is notable, as research indicates a higher incidence of the condition within this population compared to those without autism.

While other conditions listed may be associated with intellectual disabilities, they do not have the same strong correlation with autism as Fragile X disorder does. For instance, Marfan's syndrome primarily affects connective tissue and is not typically associated with intellectual disability or autism. Down syndrome is commonly recognized for its intellectual disability but is not the most frequent associated with autism when comparing these conditions. Turner’s syndrome typically impacts females and may include some cognitive deficits but is less frequently linked to autism than Fragile X syndrome. Therefore, Fragile X disorder stands out as the leading form of inherited intellectual disability associated with autism.