What does it mean when a child is born with only one line across the palm and not the "normal" 4 main lines?

Question

The child is 15 months and has this on his hands. He also has very crooked teeth, doesn't walk, and doesn't talk much. He is attentive and friendly.

Answer 1

http://www.nlm.nih.gov/medlineplus/ency/article/003290.htm

Answer 2

There is the possibility of Down Syndrome. A sign of Down's is a Simeon Crease, which is a single line through the palm of the hand as opposed to the normal M crease. Children with Down's Syndrome are known for their innocence and friendliness, and are generally very happy.

Answer 3

This child could have a form of mental retardation, but because I do not know the whole detail of your story, I cannot say for sure. I am sure that the parents have been told by a doctor if there are any problems with the child.