Down syndrome?

what are some sympotoms of Down Syndrome patients?

i know that they are overly quiet, have aggression toward others, and injur themself.

IS THERE ANYTHING ELSE?
where in the world did you here that from!?! holy cow! I am a mom to a little boy with DS and what you described is NOT related to DS it is farther from the truth. DS is not a disease it is a chromosomal disorder resulting in an extra chromosome. the characteristics of DS (not symptoms) almond shaped eyes, broader nose, thicker fungal fold at the base of the neck, shorter legs and arms, low muscle tone, ears set lower on the head, simean crease on the palm of the hand, congenital Heart defect such as av-canal, intestinal problems as well as developmental delays. not all of these need to be present either. as to them being overly quiet...LMAO come over to my house! you will see a different picture than the one you have painted. aggression towards others?...NOT! they are the most loving and compassionate people I have ever met and accept all whom they meet! they do not purposely injure themselves either.
Please don't take this the wrong way....but I just needed to let you know your assumptions are way off base.
mom to a beautiful little boy who happens to have DS