Remarkably, 2 4qter variants (4qA and 4qB) of the sub-telomeric part of the chromosome exist in the general population and are equally distributed, but FSHD is uniquely associated with the 4qA allele which contains the polyadenylation signal (p(A), ATTAAA) of DUX4 (Lemmers et al., 2002). Here, DUX4 is linked to Facioscapulohumeral dystrophy.