Fragile X syndrome (FXS) is the most common genetic cause of autism spectrum disorder (ASD).
The investigators wish to examine brain distribution of sigma-1 receptors in young adult
males with FXS using 18F-FTC-146 PET. This project will study the distribution of sigma-1
receptors in 15 young (18-30 years) male adults with FXS compared to 5 healthy adult
volunteers.