Most well-described are mutations in the X-linked gene encoding the PHD-Like Zinc Finger Protein 6 (PHF6) that associates with PAF1c and causes the ID disorder Börjeson–Forssman–Lehmann syndrome (BFLS; OMIM 301900) (Lower et al., 2002; Zhang et al., 2013). This evidence concerns the gene PHF6 and Borjeson-Forssman-Lehmann syndrome.