DUX4L9 and facioscapulohumeral muscular dystrophy: A D4Z4 proximally extended deletion (DPED) allele termed the “D4F104S1 genomic deletion”, which extends from the D4Z4 repeat array to include the DUX4c and FRG2 loci, was reported in two FSHD families (Lemmers et al., 2003; Deak et al., 2007).