Autism Spectrum Disorder and Fragile X Syndrome  Fragile X
syndrome is the most common known single gene cause of ASD  What
Is Autism Spectrum Disorder?  Autism spectrum disorder (ASD) is
a behavioral diagnosis. The range of symptoms in ASD vary and
are generally characterized by an impaired ability to
communicate and interact socially with other people. Sometimes
children will not meet the diagnostic criteria for ASD but will
have autistic-like features.  The diagnosis of ASD is usually
made by a developmental or general pediatrician, neurologist,
psychologist, psychiatrist, or other specialist. A clinician may
make a diagnosis of ASD after observing the behavior and
language of a child and using the Diagnostic and Statistical
Manual of Mental Disorders (DSM-5) criteria for their
evaluation. In addition, the diagnosis may be made after
evaluating the child using a number of testing instruments, such
as the Autism Diagnostic Observation Schedule – 2nd edition
(ADOS-2) or the Autism Diagnostic Interview – Revi