Coffin–Lowry syndrome is an example of XLID that arises as a result of X-linked dominant inheritance of mutated RPS6KA3 (ribosomal protein S6 kinase, 90 kDa polypeptide 3) on the X chromosome (Kleefstra et al., 2005). This evidence concerns the gene RPS6KA3 and cask-related x-linked intellectual disability.