For example, what is the role of MeCP2 in protracted maturation in specific neuronal populations in the olfactory system, and what are the implications of this role for neurodevelopmental disorders linked to mutations in MECP2? Further, although DCX-ir neurons in cortical layer II have been demonstrated in many mammalian species (La Rosa et al., 2020), their role remains largely elusive. Here, DCX is linked to neurodevelopmental disorder.