In this regard, our findings made through EZH1- or EZH2-specific expression are important, which not only delineate a pre-conceived pro-IH function of EZH2 (Liang et al, 2019; Lino Cardenas et al, 2019) but also uncover a previously unknown in vivo role for EZH1 in promoting IH. This evidence concerns the gene EZH2 and isolated hemihyperplasia.