Chromosomal tests on my 8 months old

My 8 month old son has some developmental delays (mostly in gross motor...he can roll and sit with support, but not quite on his own yet)Head control is good, eats great, and babbles, and interacts with us really well.  Vision is "off"...strabismus, wandering eyes, and Im pretty sure he cannot see further than a couple of feet.  Neurologist ruled out a bunch of stuff through some diagnostic tests (MRI and ultrasound of brain) and Ophthalmologist ruled out actual disease of the eye.  We were waiting on some general metabolic and genetic testing and got the results today.  

The nurse said something about a duplicate something or other and I think she said somewhere on the 4th chromosome.  She said this was a tiny area and no known disease or syndromes are linked to this particular area.  She said it may or may not be related to his difficulties, and they are now wanting to see if my husband or I contributed this particular variation to him.  She said if one of us has it, then they can rule out this variation as the cause of his problems (since we don't have problems) and consider it a normal variant or something like that.  If neither of us has it, then it MIGHT be what is causing his problems, but again not for sure.

This seems like a rabbit trail going nowhere...and I was wondering if someone here could help me make sense of this.  What does a duplicate of something in the fourth chromosome mean..?  

Im confused...and of course worried all the more for my little guy.  I don't know if this is a good thing or a bad thing.