On the other hand, data proving that microglia can be activated to the M1 phenotype simply by reduction of the H3K27me3 demethylase Jmjd3 and the fact that Jmjd3 seems to be essential for M2 microglia polarization suggest that this demethylase indeed has a pivotal role in the switch of microglia phenotypes that may contribute to the immune pathogenesis of PD (Tang et al., 2014). This evidence concerns the gene KDM6B and Parkinson disease.