Nat. Genet. 41, 868–869 (2009); published online 29 July; corrected after print 27 August 2009

In the version of this article initially published, there were two errors in the author contact information. The authors are at Scripps Genomic Medicine, Scripps Translational Science Institute and the Scripps Research Institute, La Jolla, California, USA; e-mail: kfrazer@scripps.edu or kafrazer@ucsd.edu. These errors have been corrected in the HTML and PDF versions of the article.