I have linked to a post to a blog called "Flight Platform Living".  In it a Mother blogs about her life, her family and about one of her daughters who has a genetic disability called Smith Magenis Syndrome.  Smith Magenis Syndrome is caused by a deletion on the 18th chromosome.  Some of the characteristics of SMS are;  issues with sleep, engaging personalities, varying degrees of intellectual delay, impulsivity, aggressiveness and attention seeking behavior.  They also often self injure, which is a very difficult thing for a parent to see.  I had a student in one of my classes with SMS and found him to be a very challenging child to teach, but yet couldn't help but love him.  I ended up taking him home with me one weekend, because his Mother had never had the chance to be away from him for 9 years.  Many people have never heard of SMS, even doctors I have spoken to have not often heard of it.  But if you read this blog, you will see what wonderful people they can be.