Even those of us that have children who struggle to communicate KNOW that there is more going on in those heads than can be expressed. "Mentally Retarded" and "Intellectually Disabled" may be valid labels but they should not determine the worth of the child.
This raises some serious questions about who gets to determine the value of your child's life. I suggest you read it and pass it on/repost.
If you feel moved to do something about it there are some suggestions here: