Correction to: Nature https://doi.org/10.1038/s41586-019-1056-z, published online 22 May 2019.
In Fig. 1 of this Letter, the coloured plots of significantly mutated genes (at the bottom left) were incorrect, having 23 instead of 21 plots. This error does not affect the results and conclusions of this paper. Figure 1 has been corrected in the online version of this paper.