1. Department of Epidemiology, College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
2. Department of Biomedical Informatics, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
3. Department of Human Genetics-Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
4. Department of Epidemiology and Biostatistics, School of Community and Rural Health, University of Texas Health Science Center, Tyler, TX, USA