Affiliation: | 1. Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas School of Public Health, , Houston, Texas;2. Human Genetics Center, University of Texas School of Public Health, , Houston, Texas;3. Birth Defects Epidemiology and Surveillance Branch, Texas Department of State Health Services, , Austin, Texas;4. Division of Biostatistics, University of Texas school of Public Health, , Houston, Texas |