Correction to: Translational Psychiatry (2012) 2, e201; doi:10.1038/tp.2012.125; published online 4 December 2012.

In the ‘Patients and Methods’ section, under ‘MSRV-env genomic DNA copy number in total blood leukocytes by real-time PCR,’ the paragraph ‘Results, representing the MSRV DNA copy number per diploid human genome, were obtained by calculating the ratio between HERV-W/MSRV copies and hydroxymethylbilane synthase copies in the same sample’ should have appeared as follows:

‘Relative gene quantification was performed using the 2-ΔΔCT method (Livak and Schmittgen, Methods 2001; 25: 402–408). With this method, the DNA of an unaffected individual has been used as a calibrator in order to normalize all reactions, and HBMS was used as a diploid internal control for each DNA sample as follows: 2-((Ct MSRV – Ct HBMS)—(Ctcal MSRV—Ctcal HBMS)). The results are thus expressed as a proportion of HERV-W DNA copy number as compared with the calibrator, representative of the healthy control population.’

In addition, in Figure 2, the y-axis label of panel a and the x-axis label on the three graphs in panel b were incorrect. In all four places, they should read ‘MSRV-env DNA relative quantification’. The first two sentences in the description of panel a should read ‘Relative gene quantification in DNA of patients and controls, according to the 2-ΔΔCT method (Livak and Schmittgen, Methods 2001; 25: 402–408), is indicated on the y axis.’ The first sentence in the description of panel b should read ‘Distribution of HERV-W env relative gene quantification in patients and controls.’