Thus, a bona fide poly(A) signal unique to the permissive chromosomes produced stable transcripts with greater polyadenylation efficiency than non-permissive chromosomes, thereby providing strong evidence suggesting that increased polyadenylation, and hence stability, of the distal (most telomeric) DUX4 transcript may be causally implicated in FSHD pathogenesis (Figure 1). Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.