Figure 6

Plots of cDNA versus gDNA log-ratios for 3 SNPs located in known imprinted genes. Averaged log-ratios from the 44 CEU samples in Tan et al. (2008) are shown. The first example (PEG10) provides a clear example of ASE, with the AB cDNA log-ratios (red) at similar levels to either the AA, of BB cDNA log-ratios, which is indicative of silencing. For this SNP, there is a clear linear trend between the homozygous cDNA and gDNA log-ratios. In the second example (IGF2R), there is again a linear trend, although in this case, there is no evidence for ASE, with the AB log-ratios around zero. In the final example (GABRG3), there is no obvious linear trend. This SNP provides an example of non-specific signal, where the cDNA log-ratios lie around zero irrespective of the alleles present.