KMT2D and pachyonychia congenita: Thus, the histone methyltransferases such as: EZH2, a H3‐lysine‐27‐methyltransferase enzyme; retinoblastoma protein‐interacting zinc finger gene 1 (RIZ1/PRDM2), a H3‐lysine‐9‐methyltransferase enzyme; and mixed lineage leukemia 2 (MLL2/KMT2D), a H3‐lysine‐4‐methyltransferase enzyme, have been reported to be involved in the pathogenesis of PC (Carling, Du, Fang, Correa, & Huang, 2003; Starker et al., 2011).