DAG1 and muscle-eye-brain disease: Since protein O-mannoside β1,2-N-acetylglucosaminyltransferase (POMGnT1) had recently been implicated as the cause of muscle-eye-brain disease (MEB) [35-37], Beltran-Valero de Bernabe et al. [6] screened WWS patients for mutations in the gene encoding protein O-mannosyltransferase (POMT) that attaches mannose via a O-glycosidic link to the Ser/Thr residues of α-dystroglycan, thereby synthesizing the substrate for POMGnT1.