Intrafamilial variability in GMPPB-associated dystroglycanopathy: Broadening of the phenotype

Dystroglycanopathies are characterized by deficient O-mannosyl glycosylation of α-dystroglycan (αDG) and represent an expanding genetically, biochemically, and clinically heterogeneous group of muscular dystrophies. Currently, there are 18 known genes leading to forms of α-dystroglycan–related dystrophy (αDG-RD), ranging in severity from a Walker-Warburg phenotype with severe brain malformations and hypotonia to milder childhood- or adult-onset limb-girdle muscular dystrophy (LGMD) phenotypes with or without intellectual disability.1,2