Bisulfite sequencing of the HS-40 enhancer region of the GFP transgene. (a) DNA methylation levels were reduced in Dnmt1MommeD32 heterozygous mice compared to wild-type mice in adult spleens (n = 4 wild-type mice and n = 2 Dnmt1MommeD32 mutant mice). Filled circles represent methylated CpG sites. (b) DNA methylation levels in adult spleens were unaffected in mice heterozygous for WizMommeD30 and RifMommeD18 (n = 4 for WizMommeD30 and n = 2 for Rif1MommeD18). (c) DNA methylation levels in adult spleens of RlfMommeD8, RlfMommeD28 and RlfMommeD34 heterozygotes were increased compared to wild-type mice (n = 2 mice for all genotypes). (d) Rlf homozygotes showed significantly increased DNA methylation (T-test, P < 0.05) in adult male spleen (RlfMommeD8 and RlfMommeD34) and 16.5 dpc embryo (RlfMommeD28) compared to wild types (n = 3 for all genotypes).