1 Division of Neurology (A.A.-H., H.G., K.A., J.J.D.) and Program for Genetics and Genome Biology (J.J.D.), Hospital for Sick Children; Department of Paediatrics (J.J.D.) and Deparmtent of Molecular Genetics (J.J.D.), University of Toronto, ON, Canada; Division of Neurology (A.A.-H.), King Fahad Medical City, Riyadh, Saudi Arabia; and Department of Human Genetics (S.D.), University of Chicago, IL.