Lawrence police are investigating the theft of a 7-year-old child’s walker from his frontyard at 1814 Haskell Ave.The incident occurred about 7 a.m. Wednesday. A paraprofessional helping the boy get on the school bus set the boy’s walker in the front of the house. Within minutes, the walker was gone, said the boy’s mother, Vania Bruner.The walker, valued at $1,200, is essential for the young boy who suffers from the physically debilitating Charcot-Marie-Tooth disease, a neurological disorder that affects the sensory and motor nerves, which leads to muscle weakness and atrophy.The walker is blue with a black foldup seat, black and silver arms supports, and red knobs. It has the name “Luke” on the front bar.