Epigenetic and genetic regulations are sometimes considered as separate mechanisms that influence gene expression and phenotypes. However, there are DNA sequence variants in epigenetic regulators that could affect gene regulation. The histone demethylase, KDM4C, promotes transcriptional activation by removing the repressive histone mark, tri-methylation of lysine 9 of histone H3 (H3K9me3), from its target genes. In this study, we uncovered cis-acting DNA sequence variants in KDM4C that contribute to individual differences in its expression. Utilizing this natural variation, we performed genetic analyses in B-cells in order to identify target genes that are regulated by KDM4C.