Pearls in the junk: Dissecting the molecular pathogenesis of facioscapulohumeral muscular dystrophy

Despite the discovery of the deletion on the long arm of the chromosome 4 specific for facioscapulohumeral muscular dystrophy (FSHD), the identity of the gene responsible for the disease still remains a mystery. In this review we focus on two genes, DUX4 and DUX4c, encoded by the D4Z4 repeats present in the 4q35 locus, which is affected in the disease.