Methylation levels grouped by maternal, paternal, or unknown inheritance. (A) Increased methylation of the upstream CpG sites was mainly observed in patients who had inherited the disease allele maternally, while the methylation levels of the patients who had inherited the allele paternally were comparable to those of the controls. (B) Increased methylation of the downstream CpG sites was observed in the majority of patients compared to controls, with higher degrees of methylation seen in the patients who had inherited the disease allele maternally. Boxplots indicate medians and quartiles, and the dots indicate the levels of methylation for patients who are outliers.