my son's neurologist suggested genetic testing for my son because i was pregnant at the time he was diagnosed, and he wanted to rule out any genetic links to autism, such as fragile x or some chromosome abnormalities. i don't know what the benefits to these tests are other than giving you the odds of having another child with the same disorder. (that's the reason we had the tests done). my son is on the mild end of the spectrum and from what i was told it was pretty unlikely that anything would show up in his testing. people with fragile x have some physical characteristics and individuals missing a chromosome are often diagnosed with some degree of mental retardation. ofcourse, i am not a doctor and could have this whole thing wrong....but i think that's what i was told. it's sooooo difficult to keep information straight when we are given so much at one time.