A large fraction of these contraction-independent FSHD cases is now known as FSHD2, in which hypomethylated D4Z4 repeats are combined with with a normal sized D4Z4 array on chromosome 4 permissive for DUX4 expression [22], [63]–[64]. This evidence concerns the gene SMCHD1 and facioscapulohumeral muscular dystrophy.