[1] Univ Southern Calif, Keck Sch Med, Ctr Genet Epidemiol, 1450 Biggy St, Los Angeles, CA 90033 USA
[2] Univ Calif San Francisco, Dept Epidemiol & Biostat, San Francisco, CA USA
[3] Univ Southern Calif, Keck Sch Med, Dept Pathol, Los Angeles, CA 90007 USA
[4] Childrens Hosp Los Angeles, Dept Pathol & Lab Med, Los Angeles, CA 90027 USA
[5] Duke Univ, Dept Neurosurg, Durham, NC USA