Data from the Chen and Belayew/Coppée groups were pooled in a key publication showing DUX4 mRNA extension to a PAS, detection of DUX4 mRNA and protein (with MAb 9A12) in FSHD muscle extracts, and DUX4 function as a transcription factor with Pitx1/PITX proposed as the first DUX4 target gene [26]. Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.