Nat. Genet. 47, 1471–1474 (2015); published online 9 November 2015; corrected after print 8 February 2016

In the version of this article initially published, the authors failed to acknowledge funding from the NIHR Biomedical Research Centre at Great Ormond Street Hospital for Children NHS Foundation Trust and University College London to Neil Sebire. The error has been corrected in the HTML and PDF versions of the article.