From the Kennedy Krieger Institute (Drs. Mostofsky, Cutting, and Denckla), the Department of Neurology (Drs. Mostofsky, Cutting, Denckla, and Zee and A.G. Lasker), the Department of Psychiatry (Dr. Denckla), and the Department of Pediatrics (Dr. Denckla), Johns Hopkins University School of Medicine, Baltimore, MD. (At 2001-08-14)