Who is Sister Carlotta from Ender's Shadow and what is their importance?

Sister Carlotta takes Bean off the streets of Rotterdam and prepares him for Battle School. She suspects that something might have been done to Bean's DNA that caused him to have high intelligence and slow physical development. She obtains the needed clearance to investigate and finds the scientist responsible for the idea, Anton. He explains to her that it was a very small DNA change, but that a price had to be paid for the high intelligence. She learns that Bean will grow, continue to grow into a giant, and die probably in his twenties from a failed heart.