Who is Sister Carlotta from Ender's Shadow?

Sister Carlotta takes Bean off the streets of Rotterdam and gets him ready for Battle School. While working with Bean, she comes to suspect that something might have been done to his DNA, which caused his high intelligence and slow physical development. She then gets clearance to investigate and finds the scientist responsible for the idea. Ther scientist, Anton, explains to her that it was a very small DNA change, but that a price had to be paid for the high intelligence. She also learns that Bean will grow, continue to grow into a giant, and die probably in his twenties from a failed heart.