FKRP and muscle-eye-brain disease: Mutations in the fukutin-related protein (FKRP) gene are a common cause of secondary dystroglycanopathy and are associated with a wide range of clinical features, including severe structural brain involvement resembling Walker–Warburg syndrome (WWS) and muscle-eye-brain disease (MEB), to congenital muscular dystrophy without brain involvement (MDC1C) and adult-onset limb-girdle muscular dystrophy (LGMD2I) [9–23].