More subtle alterations in TCF4 gene expression have been linked to non-syndromic intellectual disability, schizophrenia, and bipolar diseases (Pickard et al., 2005; Kharbanda et al., 2016; Maduro et al., 2016; Forrest et al., 2018; Ma et al., 2018; Mary et al., 2018). The gene discussed is TCF4; the disease is Intellectual disability.