Genetic analysis of 76 Spanish Pompe disease patients: Identification of 12 novel pathogenic GAA variants and functional characterization of splicing variants.

Glycogenosis type II (GSDII), or Pompe disease (MIM 232300), is an inherited autosomal recessive disorder caused by deficiency of the lysosomal acid-α-glucosidase. Mutations in the GAA gene alter normal enzyme production and lead to progressive buildup of intralysosomal glycogen, which plays an essential role in the severity and progression of the disease. We report here the study of 76 patients from Spain with either infantile or late onset form of Pompe disease. The analysis consisted in the molecular study of exons and intron flanking fragments of GAA gene. We have identified 55 different molecular pathogenic variants, 12 of them not previously described. In addition, we have determined a frequency of 84.37% for the c.-32-13T>G mutation in patients with the late-onset form of the disease. Functional characterization of some splice mutations showed deleterious mechanisms on the processing of mRNA.