Theresa Howard has an article about how much the expletive "you're such a retard!" wounds a mother's heart. I can certainly relate to that!
It amazes people when I tell them that there is a 60 point IQ range for individuals with Down syndrome, just as there is with the typical population, it just starts lower. There are people out there with Down syndrome who are smarter than the average Joe. So there!
HOWEVER, even if they aren't more intelligent according to some test, I have NEVER seen a person with Down sydrome call another person such a hurtful name.
They're way too emotionally intelligent for that!