These cases provide further evidence that GMPPB mutations can also cause late-onset recessive LGMD with milder phenotypes than previously reported, and thus should be considered in the differential diagnosis of patients with adult-onset muscular dystrophies.
This report expands the phenotypic spectrum of GMPPB mutations to include limb-girdle muscular dystrophies with adult onset with or without intellectual disability, or isolated rhabdomyolysis.
Mutations in GDP-mannose pyrophosphorylase B cause congenital and limb-girdle muscular dystrophies associated with hypoglycosylation of α-dystroglycan.
GMPPB catalyzes the formation of GDP-mannose, which is an essential precursor of glycan moieties of glycoproteins and glycolipids and is associated with congenital and limb-girdle muscular dystrophies with hypoglycosylation of α-dystroglycan.