Fragile X Syndrome: A Comprehensive Review of Etiology, Pathophysiology, and Management

Fragile X syndrome (FXS) is the most common inherited single-gene cause of intellectual disability and a significant genetic cause of autism spectrum disorder. The disorder exhibits variable expressivity and reduced penetrance, particularly in females due to X-chromosome inactivation.

Clinically, FXS is associated with intellectual disability, behavioral problems, anxiety, and autism-related features. Diagnosis is primarily performed using molecular genetic techniques such as polymerase chain reaction (PCR) and Southern blot analysis to detect CGG repeat expansion and methylation status in the FMR1 gene. This chapter presents a comprehensive overview of the etiology, pathophysiology, diagnosis, and management of Fragile X syndrome.