Of those with fragile X syndrome, prevalence of concurrent autism spectrum disorder (ASD) has been estimated to be between 15 and 60%, with the variation due to differences in diagnostic methods and the high frequency of autistic features in individuals with fragile X syndrome not meeting the DSM criteria for an ASD.Although individuals with FXS have difficulties in forming friendships, those with FXS and ASD characteristically also have difficulties with reciprocal conversation with their peers. Social withdrawal behaviors, including avoidance and indifference, appear to be the best predictors of ASD in FXS, with avoidance appearing to be correlated more with social anxiety while indifference was more strongly correlated to ASD. When both autism and FXS are present, a greater language deficit and lower IQ is observed as compared to children with only FXS.Genetic mouse models of FXS have also been shown to have autistic-like behaviors. Social interaction
FXS is characterized by social anxiety, including poor eye contact, gaze aversion, prolonged time to commence social interaction, and challenges forming peer relationships. Social anxiety is one of the most common features associated with FXS, with up to 75% of males in one series characterized as having excessive shyness and 50% having panic attacks.
Medications may be used to treat associated seizures, mood problems, aggressive behavior, or ADHD. Fragile X syndrome is estimated to occur in 1.4 per 10,000 males and 0.9 per 10,000 females. Signs and symptoms
Most young children do not show any physical signs of FXS. It is not until puberty that physical features of FXS begin to develop. Aside from intellectual disability, prominent characteristics of the syndrome may include an elongated face, large or protruding ears, flat feet, larger testes (macroorchidism), and low muscle tone. Recurrent otitis media (middle ear infection) and sinusitis is common during early childhood. Speech may be cluttered or nervous. Behavioral characteristics may include stereotypic movements (e.g., hand-flapping) and atypical social development, particularly shyness, limited eye contact, memory problems, and difficulty with face encoding. Some individuals with fragile X syndrome also meet the diagnostic criteria for autism.Males with a full mutation display virtually complete penetrance and will therefore almost always display symptoms of FXS, while females with a full mutation generally display a penetrance of about 50% as a result of having a second, normal X chromosome. Females with FXS may have symptoms ranging from mild to severe, although they are generally less affected than males.