A previous summary pointed out that, among the nine patients with XLI reported in the literature (Khelifa et al., 2013), five patients had different degrees of intellectual disability, only one of which had a deletion of NLGN4X. Another patient who had a deletion of NLGN4X demonstrated normal mental development (Khelifa et al., 2013). Here, NLGN4X is linked to Intellectual disability.