Similar to their counterparts in other dystroglycanopathy genes, B4GAT1(B3GNT1) loss-of-function mutations in human patients result in Walker-Warburg Syndrome (WWS) (Buysse et al., 2013; Shaheen et al., 2013), the most severe condition in a range of clinically defined CMDs that are accompanied by brain and eye malformations. The gene discussed is B4GAT1; the disease is muscular dystrophy-dystroglycanopathy, type A.