FMR1 and autism spectrum disorder: For instance, mutations in FMR1, mainly through trinucleotide expansion of CGG repeats in the 5′ untranslated region (UTR) and rarely through missense mutations in the coding region, is known to result in fragile X syndrome, the most common inherited form of mental retardation and single-gene cause of autism spectrum disorder, by dysregulating local translation in neurites critical for synaptic formation and functions61,62.