In order to estimate the de novo CNV rate in controls for comparison with cases, we compared the case de novo rate with that in controls from two sources, the Icelandic population controls and the unaffected sibs from a recent large study of autism25 (Supplementary Table S3). The de novo mutation rate in our cases was higher than in both sets of controls (2.2%, P=0.00015 and 1.6%, P=0.00008, respectively), both of which had a similar rate (P=0.28) despite differences in the density of markers in the control genotyping platforms.
