SOX2 and Intellectual disability: Both Gpr56, a gene whose promoter is bound by SOX2, and Arid1a (Figure 3) are connected to distant SOX2-bound epigenetic enhancers; mutation of the GPR56 promoter causes structural neocortical abnormalities and ARID1A mutation is responsible for intellectual disability (Bae et al., 2014, Lee and Young, 2013, and references therein).