Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA.|Vanderbilt Genetics Institute, Dept. of Molecular Physiology and Biophysics, Vanderbilt University Medical School, Nashville, TN, USA.|Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA.|Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA.|Key Laboratory of Resource Biology and Biotechnology in Western China, School of Life Sciences, Northwest University, Xian, Shaanxi, China.|Department of Internal Medicine, University of New Mexico, Albuquerque, NM, USA.