Notably, the dystroglycan-related muscular dystrophies are primarily “secondary dystroglycanopathies” caused by mutations in any one of a number of glycosyltransferases, such as fukutin (Fktn) and fukutin-related protein (Fkrp), which are necessary to synthesize an elaborate O-mannose glycan, the substrate for α-dystroglycan binding with extracellular matrix proteins[12]. Here, DAG1 is linked to neuromuscular disease caused by qualitative or quantitative defects of alpha-dystroglycan.