BDNF and atypical Rett syndrome: In the Rett syndrome, a mutation in the transcriptional repressor MeCP2 (methylated-cytosine binding protein) alters the expression of several genes, including Brain-Derived Neurotrophic Factor (BDNF), where its dysregulation seems to play a critical role in the neurobiological consequences of this syndrome (Li and Pozzo-Miller, 2014).