In the literature, only two DUX4 APA sites have been described: one in exon 7 [11], which may be used in testis only and one in exon 3, located ~40 nt upstream of the canonical one, and sometimes observed after treatment of FSHD cells with antisense oligonucelotides targeting the DUX4 PAS [19]. This evidence concerns the gene DUX4 and Facioscapulohumeral dystrophy.