Jack (1996)

Jack Powell appears to be an average, middle-aged forty year old man--who plays with G.I. Joe and wears Power Ranger pajamas. But Jack is only 10-years-old. He suffers from a genetic disorder that causes him to physically age four times faster than a normal person. Fearing ridicule from the outside world, Jack's parents have kept him secluded in their home, which they have stocked with every toy a young boy could want. Toys can't take the place of the real friends which Jack craves. Now he's about to embark on the greatest adventure of his unusual life--he's about to enter the fifth grade.