BDNF and atypical Rett syndrome: Moreover, CAPS2 KO mice impairments in the GABAergic system and BDNF secretion may be related to the other ASD gene candidates (Table 1), such as the GABRB3 gene, encoding the GABAA receptor β-3 subunit, and the MeCP2 gene, the causative gene of Rett syndrome and encoding a methyl-CpG-binding protein implicated in transcriptional regulation of the BDNF gene.