Nat. Med.; 10.1038/nm.3628; corrected 25 August 2014

In the version of this article initially published online, the nucleotide numbering of the AS (−3 to + 16), B (+17 to +40) and C (+49 to −10) targeted sequences in Figure 3b was incorrect, and thus the schematic of the sequences was incorrectly drawn. The correct numbering is as follows: AS, −3 to + 18; B, +17 to +44; and C, +49 to −8. The correction has no impact on the results of the study or its conclusions. The error has been corrected for all versions of this article.