However, we have previously demonstrated that the alleles of chromosome 4 and 10 that are non-permissive for FSHD contain polymorphisms that inhibit polyadenylation of the DUX4 transcript, and, therefore, only the 4A allele would be predicted to make a DUX4 mRNA [8]. Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.