The clinical findings in males with a full mutation may include the following:

  • Intellectual disability (IQ may range from 22-65).

  • Behavioral differences may include:
    • Autism spectrum disorder
    • Hyperactivity
    • Shyness
    • Gaze aversion
    • Hand flapping
    • Hand biting
    • Temper tantrums  
  • Specific facial appearance and physical findings which may include:
    • Large head
    • Long face
    • Large forehead and chin
    • Ears that stick out
    • High arched palate or sometimes cleft palate

  • Macroorchidism  - not apparent until after puberty

  • Joint hypermobility

  • Cardiac findings include mitral valve prolapse and aortic root dilatation.

  • Strabismus  

  • Other findings may include:
    • Hypotonia
    • Reflux
    • Recurrent otitis media
    • High blood pressure
    • Seizures.  


Clinical finding in females who have a full mutation:

  • Females may have some of the same physical features as males.

  • Mild intellectual disability in up to 50% of females (IQ may range from 74-91). 

  • Other learning difficulties or subtle cognitive features, such as difficulty with math

  • Behavioral differences may include the following:
    • Social anxiety
    • Selective mutism
    • Excessive shyness
    • Poor eye contact
    • Hyperactivity, and/or impulsive behavior.