PITX2 and facioscapulohumeral muscular dystrophy: Mutations or misregulation of Pitx1, Pitx2, and Pitx3 result in developmental disorders in humans, such as Facioscapulohumeral Muscular Dystrophy (FSHD; Dixit et al., 2007), Axenfeld-Rieger syndrome (Semina et al., 1996), and Anterior Segment Mesenchymal Dysgenesis (ASMD; Semina et al., 1998), respectively.