A subset of imprinted genes in the Snrpn cluster shows increased expression in Smchd1 mutants. ( A ) The Snrpn imprinted gene cluster, where those genes expressed from the paternal allele are shown in blue and those expressed from the maternal allele are in red. CpG islands are represented by circles on the line and where these represent an sDMR (small circles) or imprint control region (ICR) (large circle) the methylation status is indicated (M inside the filled circle for the methylated allele or unfilled circle for the unmethylated allele). Quantification of the expression levels of imprinted genes or transcripts within the Snrpn cluster by qRT-PCR measured using RNA derived from: ( B ) male and female E9.5 embryos, ( C ) mouse embryonic fibroblasts (MEF) derived from male E14.5 embryos, and ( D ) whole brain from adult male mice. The synthesis of first-strand cDNA from E9.5 embryo RNA was primed with oligo dT, but for the analysis of transcript levels in MEFs and brain the cDNA synthesis was primed with a cocktail of the reverse primers used for qRT-PCR. In each case the qRT-PCR signal was normalized relative to that of Rala and plotted relative to the corresponding Smchd1+/+ sample. The genotype, sex, and number of replicates are indicated in each case. Statistical analysis was performed using the t test. ** P < 0.01 and * P < 0.05 compared with wildtype. Error bars indicate standard error.