Nat. Genet.; doi:10.1038/ng.3432; corrected online 17 November 2015

In the version of this article initially published online, the Online Methods incorrectly abbreviated mapping quality as MAQ rather than MAPQ. Also in the Online Methods, the procedure for downsampling allele counts for cross–cell type analysis of imbalance was incorrectly written as “we subsampled each site to three cell types and further downsampled the allele counts to mapping quality for the lowest of the three cell types.” The sentence should read “we subsampled each site to three cell types and further downsampled to the allele counts to match the lowest of the three cell types.” The errors have been corrected for the print, PDF and HTML versions of this article.