Screening of Late-Onset Pompe Disease in a Sample of Mexican Patients With Myopathies of Unknown Etiology: Identification of a Novel Mutation in the Acid α-Glucosidase Gene

Pompe disease or glycogen-storage disease type 2 (GSD2, OMIM 232300) is an autosomal recessive disorder caused by mutations in the acid alpha-glucosidase gene. Late-onset GSD2 resembles some limb-girdle and Becker muscular dystrophies. The screening of GSD2 through the measurement of acid alpha-glucosidase activity in dried blood spots was applied to a selected sample of 5 Mexican patients with proximal myopathies of unknown etiology. Only 1 male patient showed a low level of acid alpha-glucosidase activity and a compound heterozygote genotype for the c.-32-13T > G splicing mutation present in most white late-onset Pompe disease cases and the novel mutation p.C558S. To our knowledge, this is the first report of a Mexican patient with late-onset GSD2. The identification of c.-32-13T > G in our patient could reflect the genetic contribution of European ancestry to the Mexican population. The enzymatic screening of GSD2 could be justified in patients with myopathies of unknown etiology.