1. Department of Statistics and Operations Research The University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA
2. Department of Biostatistics The University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA
3. Department of Genetics The University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599‐7264 USA
4. Carolina Center for Genome Sciences The University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA
5. Lineberger Comprehensive Cancer Center The University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA