DAG1 and neuromuscular disease caused by qualitative or quantitative defects of alpha-dystroglycan: α-Dystroglycanopathy (α-DGP) is a genetically and clinically heterogeneous group of muscular dystrophy1, 2 for which more than 15 causative genes have been identified3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21: POMT1, POMT2, POMGnT1, fukutin, FKRP, LARGE, ISPD, GTDC2 (POMGnT2), DAG1, TMEM5, B3GALNT2, SGK196 (POMK), B3GNT1 (B4GAT1), GMPPB, DOLK, DPM1, DPM2 and DPM3.