1. Social, Statistical, and Environmental Sciences, RTI International, Research Triangle Park, North Carolina;
2. Departments of Pediatrics and
3. Neurologic Sciences, Rush University Medical Center, Chicago, Illinois;
4. Department of Pediatrics, M.I.N.D. Institute, University of California at Davis Medical Center, Sacramento, California;
5. Department of Pediatrics and Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina;
6. M.I.N.D. Institute, University of California at Davis Medical Center, Sacramento, California;
7. Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina