Nat. Genet. 49, 238–248 (2017); published online 9 January 2017; corrected after print 20 March 2017

In the version of this article initially published, the legend to Figure 4c stated that only one proband without SMCHD1 mutation was tested for D4Z4 methylation pattern. However, three probands and one affected family member without SMCHD1 mutation were tested, as shown in the figure. The error has been corrected in the HTML and PDF versions of the article.