Examples include mutant paired like homeobox 2B (mutant PHOX2B) in congenital central hypoventilation syndrome (CCHS) (Amiel et al, 2003), mutant RUNX family transcription factor 2 (mutant RUNX2) in cleidocranial dysplasia (Mundlos et al, 1997), mutant homeobox D13 (mutant HOXD13) in synpolydactyly (Muragaki et al, 1996), and mutant poly(A) binding protein nuclear 1 (mutant PABPN1) in oculopharyngeal muscular dystrophy (OPMD) (Richard et al, 2017). Here, HOXD13 is linked to cleidocranial dysplasia 1.