[1] Univ Southern Calif, Dept Neurosurg, Keck Sch Med, Los Angeles, CA USA
[2] Univ Southern Calif, Ctr Genet Epidemiol, Norris Comprehens Canc Ctr, Los Angeles, CA USA
[3] Yale Sch Publ Hlth, Dept Chron Dis Epidemiol, New Haven, CT USA
[4] Univ Calif Berkeley, Sch Publ Hlth, Dept Epidemiol, Berkeley, CA USA
[5] Yale Sch Med, Dept Internal Med, New Haven, CT USA
[6] Univ Southern Calif, Keck Sch Med, Dept Neurosurg, 1200 N State St,Suite 3300, Los Angeles, CA 90033 USA