KMT2D and cancer: KMT2D was a gene of histone methyltransferase that methylates the Lys-4 position of histone H3, and there some research in other cancers (Guo et al., 2013; Toska et al., 2017; Xiong et al., 2018; Li et al., 2019; Sun et al., 2019; Alam et al., 2020; Zheng et al., 2021), but there was still a lack of reports in ESCC (Abudureheman et al., 2018).