Nat. Genet.; 10.1038/ng.3769; corrected online 13 February 2017

In the version of this article initially published online, there were two errors. In the section “Three classes of monoallelic elements” in the main text, “We classified all monoallelically accessible elements (1,966 elements)” should have read “1,964 elements.” In the legend for Figure 5c, the number of elements open in ESCs should have been given as 234 instead of 35. The errors have been corrected in the print, PDF and HTML versions of this article.