DAG1 and neuromuscular disease caused by qualitative or quantitative defects of alpha-dystroglycan: Two recently identified genes that encode for dolichol-phosphate-mannose synthase (DPM) subunits DPM2 [14] and DPM3 [15] have also been found to be defective in patients with a dystroglycanopathy phenotype, consistent with the role of the DPM complex in the synthesis of glycan precursors for the O-mannosyl glycosylation of α-dystroglycan.