Certified Rehabilitation Counselor Practice

What is the most common inherited form of intellectual disability?

1. Huntington's disease

2. Fragile X syndrome

3. Down syndrome

4. Autism spectrum disorder

The correct answer is: Fragile X syndrome

Fragile X syndrome is recognized as the most common inherited form of intellectual disability due to its genetic basis linked to mutations in the FMR1 gene on the X chromosome. This condition is particularly notable because it affects both males and females, although males tend to exhibit more severe symptoms due to the presence of only one X chromosome. Fragile X syndrome leads to developmental delays and cognitive impairment, and it is associated with various behavioral issues, including challenges with social interaction and communication. Understanding this syndrome's prevalence as an inherited condition underscores the importance of genetic factors in intellectual disabilities. In contrast, Huntington's disease is primarily associated with motor disorders and cognitive decline, often appearing in mid-adulthood, while Down syndrome is caused by chromosomal abnormalities rather than being solely inherited. Lastly, autism spectrum disorder encompasses a range of developmental conditions but is not classified strictly as an intellectual disability and can vary widely in severity and the nature of symptoms.