Age-related methylation in normal colon mucosa differs between the proximal and distal colon in patients who underwent colonoscopy

Objectives To examine the difference in the methylation status in normal colon mucosa between the proximal and distal colon, in relation to the correlation between the methylation status of normal mucosa and characteristics of neoplasia. Design and methods Paired biopsy specimens of normal mucosa from the proximal and distal colon of 82 patients who underwent colonoscopy were obtained. The methylation status of the promoter region of estrogen receptor 1 (ESR1) and myogenic differentiation 1 (MYOD1) was examined. Results Normal mucosa was more highly methylated in the distal than in the proximal colon in both ESR1 and MYOD1 loci (p < 0.0001 and p = 0.0009, respectively). Advanced characteristics of polyps in the distal colon were frequently observed in patients with lower methylation of ESR1 in the distal colon normal mucosa. Conclusions Methylation levels in normal mucosa differ between the proximal and distal colon, and lower methylation of ESR1 in the distal colon normal mucosa may correlate with advanced features of neoplasia in the distal colon.