FXN and Friedreich ataxia: On the other hand, a recent study targeting G9a and EZH2 HMTs reported, in addition to changes in H3K9me2/me3 and H3K27me3 levels, an increase of FXN mRNA expression in FRDA fibroblasts but without noticeable effects on FXN protein levels (Sherzai et al., 2020).