MECP2 and atypical Rett syndrome: Further, another important heterochromatin protein, methyl CpG binding protein 2 (MeCP2), has been suggested to drive heterochromatin condensate formation in association with DNA, and mutations that disrupt the ability of MeCP2 to form condensates in vitro are found in patients with the neurodevelopmental disorder Rett syndrome (Li et al., 2020).