DAG1 and neuromuscular disease caused by qualitative or quantitative defects of alpha-dystroglycan: Only one case has been reported so far with a pathogenic mutation in the dystroglycan (DAG1) gene itself [9], which therefore represents a primary dystroglycanopathy; the other eight genes encode proteins with confirmed or putative roles in the glycosylation of α-dystroglycan and are therefore secondary dystroglycanopathies.