Author information:
(1)Department of Human Genetics, The University of Chicago, 920 E. 58th Street, 
Chicago, IL, 60637, USA. spott@uchicago.edu.
(2)Department of Human Genetics, The University of Chicago, 920 E. 58th Street, 
Chicago, IL, 60637, USA. jdlieb@uchicago.edu.