Expanded [CCTG]n repetitions are not associated with abnormal methylation at the CNBP locus in myotonic dystrophy type 2 (DM2) patients

Moreover, we compared the relative mRNA transcript levels of CNBP gene in leukocytes and in skeletal muscle tissues from controls and DM2 patients. We found that CpG sites located in the promoter region showed hypomethylation, whereas CpG sites at 3′ end of the CCTG array are hypermethylated. Statistical analyses did not demonstrate any significant differences in the methylation profile between DM2 patients and controls in both tissues analyzed. According to the methylation analysis, CNBP gene expression levels are not significantly altered in DM2 patients. These results show that [CCTG]n repeat expansion, differently from the DM1 mutation, does not influence the methylation status of the CNBP gene and suggest that other molecular mechanisms are involved in the pathogenesis of DM2.