Stanford University - Department of Epidemiology and Population Health, University of California, San Francisco (UCSF) - Department of Epidemiology and Biostatistics, Stanford University - Department of Pediatrics, University of California, San Francisco (UCSF) - Department of Biochemistry & Biophysics, University of California, San Francisco (UCSF) - Department of Biochemistry & Biophysics, Stanford University - Quantitative Sciences Unit and Stanford University - Department of Pediatrics