Fig. 3

Distribution of reference allele frequency after removing SNP that were likely to be a sequencing error, within tissue type, for all SNP tested for ASE. If there was significant mapping bias still present after mapping to the two parental genomes the distribution of allele frequencies would be skewed toward the reference allele. Instead it followed a normal distribution with a peak at reference allele frequency of 0.5, except for those SNP with reference allele frequency of 0 or 1. As discussed in the text these represent SNP that display monoallelic expression and even though attempts were made to remove SNP that were due to sequencing errors, higher peaks at reference allele frequency of 1, as compared with 0, indicate some still remain