Variation in occurrence of malformations at birth is not correlated with 5′ LTR promoter methylation.

Independent clones generated by PCR were sequenced and analyzed for CpG methylation at 8 sites (7 LTR and 1 X chromosome genomic) upstream of the 5′ LTR in 2 Ppd carrier females with normal phenotypes (NL-Ppd) versus 2 Ppd carrier females with abnormal phenotypes (A-Ppd). The number of clones for each sample with the indicated number of methylated CpGs are tabulated. No difference was observed at these CpG sites either in number or distribution of sites of methylation between these groups. For comparison, CpG methylation was also assessed in affected and unaffected Ppd males and in ES cell line Ppd-D5. In this ES cell line the LTR is almost completely unmethylated, whereas in postnatal adult males the ETn LTR is methylated to a variable extent, but less than in females. cm = caudal mass tissue of mouse #3412.