Fragile X syndrome and Autism Spectrum Disorder: Is ASD in FXS ‘true’ ASD?

Autism & Fragile X syndrome are intertwined as they share some neurochemical similarities. Fragile X Syndrome (FXS) is the second cause of intellectual disability after Down syndrome and the most prevalent cause of intellectual disability in males. The actual worldwide prevalence is affecting 1:5000–7000 men and 1:4000–6000 women. In Egypt, the prevalence of FXS mutation among Egyptian males was 0.9 per 1000. Moreover, it was 6.4% among mentally subnormal males. ASD is a common comorbid condition in people with fragile X syndrome (FXS). Fragile X Syndrome is caused by an alteration of the FMR1 gene, which maps at the Xq27.3 band: more than 99% of individuals have a CGG expansion (>200 triplets) in the 5′ UTR of the gene, and FMR1 mutations and duplication/deletion are responsible for the remaining (