What you describe here fits a student that I had about 3 or 4 years ago in 6th grade. She never said word unless you asked her to read orally. She never refused to read, but sometimes she would sit for several minutes not answering questions directed to her during class discussion. She seldom smiled, either.
We, as a team of her teachers, tried to "bring her out of her shell", but nothing we tried worked. Finally, one of the teachers began to dole out punishments (very mild ones) because this child refused to ask questions to clarify directions on worksheets or other assignments. Her grades were fair, but could have been better. She seemed like she disliked being in school, but she never missed a day. We would sometimes see her after school hours riding her bike, but she never acknowledged us with a smile, wave, etc. She seemed like a very sad child.
A couple years later, we had her sister. She, too, was quiet, but not quite like the older one. Right now, I have their younger brother -- he's NOTHING like either of them.
Do you know where a person could find more information about this? I didn't know it could have a name. I wish we had known this when she was in our classes.