Severe Muscle–Eye–Brain (MEB) disease and Walker–Warburg syndrome can also originate from dystroglycan mutations (primary dystroglycanopathies) [12], while a plethora of congenital or milder conditions, collectively called secondary dystroglycanopathies, can arise from mutations hitting several accessory enzymes, located in the endoplasmic reticulum (ER) and Golgi, which are crucial for α-dystroglycan glycosylation. Here, DAG1 is linked to muscular dystrophy-dystroglycanopathy, type A.