A method is provided for treating a Mendelian disorder of the epigenetic machinery in a subject in need thereof. In particular, the method comprises administering a therapeutically effective amount of an agent that restores balance between open and closed chromatin states at one or more target genes, wherein the agent that restores balance between open and closed chromatin states at one or more target genes is an agent that ameliorates the effect of a defective gene encoding a component of the epigenetic machinery.
