CDKL5 and Intellectual disability: Moreover, CDKL5, which phosphorylates NGL-1 to promote interactions between NGL-1 and PSD-95 and positively regulates excitatory synaptic structure and function (Ricciardi et al., 2012), is associated with Rett syndrome, epilepsy, intellectual disability, and ASD (Posar et al., 2015; Zhou et al., 2017; Zhu and Xiong, 2019).