Yes I have... More than one... My second cousin has the severe form of autism - such a cute boy, one of the cutest kids I have ever seen and then he was diagnosed with autism.. I havent seen him for a long time now, but I know he attends the special school for his kind of kids... I have never heard him utter a word!! He would never look at you and only responds when his mom calls him...
Then I have others in my family with the mild form of autism - they talk, they look at you, they read and write very well, they tell stories, at times they say jokes and do not realize they are funny and at times they say things and laugh when it isnt really funny... The one thing about them is that despite all the behavioural issues they have, they have very high IQ - no one can beat them in their Math and Science ability, and they are very inventive too and artistic to an extent... So there are both positiives and negatives to it...