Search is on for 20-year-old Isaac Wilkie, a young man with autism who disappeared three days ago from his Harlem home. His loved ones have posted pictures of him near his home and have issued a desperate plea for help in finding him. Wilkie was last seen leaving his home on Monday evening and is likely in distress due to the hot weather. He is described as about 5'5'' tall, weighing about 220 pounds, last seen wearing blue jeans, a cream-colored shirt and green sneakers. There is a potential sighting of him on a bus on the Upper East Side.