The current paradigm suggests that pathogenicity of D4Z4 at 4q35.2 is linked to FSHD through a D4Z4 gene encoding Double Homeobox Protein 4 (DUX4) [5], [4], [6]; however, its pathogenic mechanism is unclear. The gene discussed is DUX4; the disease is facioscapulohumeral muscular dystrophy.