Our results showed a positive correlation between neuropathic pain states and DNA methylation levels of CpG -97, -53 and -51 in the promoter region of TRPA1in the whole blood, which corresponds to the relationship between the DN4 score and DNA methylation rate at CpG -51 of TRPA1 in chronic pain patients shown in our previous study.[6] These results suggest that DNA methylation at the promoter region of TRPA1 in peripheral blood might be associated with the presence of neuropathic pain characteristics in humans. Here, TRPA1 is linked to chronic cystitis.