A notable regulatory feature of the DUX4 promoter is the increase in transcription as human myoblasts begin to form myotubes in cell culture, shown previously by detection of transcripts and protein in human FSHD fibroblasts converted to myotubes by myoD expression and in myotube/myoblast pairs [4]. The gene discussed is MYOD1; the disease is facioscapulohumeral muscular dystrophy.