However, when methylation status was classified only into unmethylated (<9%) and methylated (≥9%), a statistically significant difference was observed only for the VDR promoter and the distal promoter region of the CLDN14 gene, leading to the hypothesis that epigenetic changes of these two genes’ expression patterns may be of fundamental importance in recurrent kidney stone formation. Here, CLDN14 is linked to nephrolithiasis.