FKTN and limb-girdle muscular dystrophy: Mutations in the genes coding for isoprenoid synthase domain‐containing protein (ISPD), fukutin‐related protein (FKRP), and fukutin (FKTN) cause distinct forms of secondary dystroglycanopathies, ranging from the milder limb girdle muscular dystrophy (LGMD) to the severe multisystem Walker‐Warburg syndrome.1