Fragile X Syndrome

Abstract

Fragile X syndrome (FXS) is the most commonly inherited form of mental retardation and developmental disabilities, affecting 1 in 4000 individuals. The phenotype of FXS involves mental retardation or learning disabilities, social deficit, anxiety, attention deficit, impulsivity, hyperarousal, mood instability, inflexibility, prominent ears, long face, and hyperextensible finger joints. Although most babies with FXS have hypotonia and mild motor delays, the diagnosis of FXS may not be made until more significant language delays are present at 2.5–3 years of age. Clinicians and parents should be aware of the features of FXS so that early diagnosis can be made to facilitate early intervention and genetic counseling.