1. Neuroepidemiology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD,
2. Neuroepidemiology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD
3. Department of Genetic Medicine, Valley Children's Hospital/University of California-San Francisco, Madera, CA
4. California Birth Defects Monitoring Program, California Department of Health Services, Emeryville, CA