Archivist: De novo mutations and severe nonsyndromic intellectual disability (Arch Dis Child 2013;<B>98</B>:102). The second half of this paper was published in error as part of the same article. The new paper begins at “Antenatal steroid therapy…” and finishes at “for antenatal steroid therapy”. The correct version is published in this issue with its own doi (10.1136/archdischild-2012-303542). We would like to apologise to the author for any embarrassment caused by our mistake.