That was my dd a couple of years ago. She was amazing with her skills but I was so worried about her social/emotional behavior that I took her to a child psychologist. At the time she was 3.5 and not PT yet, tuned out, sang to herself (preferred that to people), used movie lines instead of talking with her own words, raging tantrums, never slept. It was really hard. The psych said that she had traits of mild autism, that she was very gifted, that she had traits of ADD. But she didn't have autism or ADD, she just had those traits sometimes. She chose to go into her own world sometimes but then came out of it.
She got better. We figured out she had seasonal allergies and I gave her Claritin. It was a dramatic improvement. She was dx with sensory issues but has since improved with those. The allergy meds increased her appetite and she was able to eat better, be better nourished, get over her constitpation.
We do feel that SID runs in the family. Her baby sister was dx with it and is trying to wean off a feeding tube because of eating aversions. She went through OT earlier on and benefitted from that and the nutrition. She's now 5.5 and very social, has slowed down with the early skills but it still ahead. I would not consider her extremely gifted anymore, just bright and creative. She still doesn't sleep well but she's learned to be quiet so the rest of us can sleep. She still has sensory issues but they are way better now. You would normally notice them except the occasional toe walking or licking things innapropriately.
So that's her story.

Her sister is getting better, too. Because of good nutrition through the tube, treatment for allergies, early OT, she's actually more social than her sister and I worry less about her long-term ability to cope with stress and fit into society.