I have 2 children with the microduplication. Their father is the carrier. My son who is 10 has more symptoms than my daughter who is 14. Both had bad reflux and were late walkers. I do not recall any problems with sitting. My son was also a late talker and needed speech therapy. His speech is fine now. He does have significant learning issues and his psychiatrist says he is probably 2-3 years behind both cognitively and socially. He is ADHD, has processing issues, sensory issues and fights bouts of depression.
If you have not had a chance, check out the yahoo group 22c. Lots of members with lots of info. However I will warn you that it can be overwhelming. There are kids with major issues such as g-tubes, etc but also some with mild symptoms. Treatment wise CHOP in Philly is the place to be.
Hope this helps. Please let me know if you have any other questions. Good Luck! Stephanie