DNA methylation profile at the DMPK locus in DM1 blood samples representing all clinical subtypes. (A) Schematic representation of the four CpGis residing in the DMPK locus and neighboring genes. CpGi 374 is divided into the CTCF1 and CTCF2 region, harboring the CTCF binding sites and encompassing the CTG expansion. (B) Summary of the methylation profiles of the five CpG regions across the DMPK locus in the studied clinical subtypes, in which black indicates the degree of methylation. Congenital n = 6, Childhood n = 6, Juvenile n = 23, Adult n = 22, Late onset n = 6, asymptomatic n = 2, Controls n = 8. (C) Detailed DNA methylation profiles of the clinical subtypes in the CTCF1 and CTCF 2 regions. Each circle represents a CpG dinucleotide. The colour gradient represents the level of methylation indicated in the legend assessed by sodium bisulphite sequencing. Red indicates paternal inheritance. Black indicates maternal inheritance. * means unknown inheritance. For the non-developmental cases, only a representative subset of three samples is displayed. Detailed methylation profiles of all patients in all categories can be found in the supplemental tables. Abbreviations: DMWD = dystrophia myotonica WD repeat-containing gene, DMPK = myotonic dystrophy protein kinase gene, SIX5 = six homeobox 5 gene, CTG(n) = the CTG expansion, CpGi = CpG island, Asymp = asymptomatic, C = control, P = DM1 patient.