GNPTAB and mucolipidosis type II: Mutations in GNPTAB can result in mucolipidosis type II (MLII alpha/beta, I-cell disease) clinically characterized by impaired skeletal growth, progressive osteodystrophy, destructive bone lesions (‘dysostosis multiplex’), facial dysmorphism, psychomotor retardation, cardiorespiratory defects and early death between 5 and 8 years of age (Braulke et al, 2013; Cathey et al, 2010; Spranger & Wiedemann, 1970).