1. Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, 08544 NJ, USA
2. Analytic and Translational Genetics Unit, Department of Medicine, Massachusetts General Hospital, Boston, 02114 MA, USA
3. Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, 02142 MA, USA
4. Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, 02142 MA, USA
5. Department of Statistics, Carnegie Mellon University, Pittsburgh, 15213 PA, USA
6. Department of Statistics, Harvard University, Cambridge, 02138 MA, USA