Department of Statistics, University of Nebraska Lincoln, Lincoln, Nebraska, USA. qi.zhang@unl.edu.|Department of Statistics, University of Wisconsin Madison, Madison, Wisconsin, USA.|Department of Biostatistics and Medical Informatics, University of Wisconsin Madison, Madison, Wisconsin, USA.|Department of Genetics, Stanford University School of Medicine, Palo Alto, California, USA. trupti@stanford.edu.|Department of Genetics, Stanford University School of Medicine, Palo Alto, California, USA. mpsnyder@stanford.edu.|Department of Statistics, University of Wisconsin Madison, Madison, Wisconsin, USA. keles@stat.wisc.edu.