Fragile X Syndrome

Abstract

Fragile X syndrome (FXS) is the leading inherited form of intellectual and developmental disabilities, affecting 1 in 4000 individuals. The phenotype of FXS involves both physical as well as developmental characteristics including significant cognitive impairment or learning disabilities, anxiety, attentional deficits, impulsivity, hyperactivity, hyperarousal, mood instability, inflexibility, prominent ears, long face, and low muscle tone. Due to its X-linked genetic pattern, males are typically more involved than females. Although most babies with FXS have hypotonia (low muscle tone) and mild motor delays, the diagnosis of FXS is often not made until more significant delays are evident typically between 2.5 and 3 years of age. Although there is currently no cure, it is important for interventionists to be aware of the characteristics because an early and accurate diagnosis can facilitate access to services -- such as early intervention and genetic counseling -- that are important to the child and their family.