Indeed, besides the well-known pathological traits - intellectual disability and delayed development - caused by MeCP2 duplication (Ramocki et al., 2010) or MeCP2 loss of function (Chahrour and Zoghbi, 2007), even mild differences in MeCP2 expression turned out to profoundly impact human behavior and brain function (Tantra et al., 2014). The gene discussed is MECP2; the disease is Intellectual disability.