[Two new mutations in the gene that codes for acid alpha-glucosidase in an adolescent with late-onset Pompe disease]

INTRODUCTION. Glycogen storage disease type II, or Pompe disease, is a lysosomal disease with an autosomal recessive pattern of inheritance. Late-onset Pompe disease is a progressive metabolic myopathy caused by decreased activity of the enzyme acid alpha-glucosidase (GAA), which gives rise to reduced degradation and later accumulation of glycogen in the lysosomes and cell cytoplasm. CASE REPORT. A 16-year-old Venezuelan male, diagnosed with late-onset glycogen storage disease type II, or Pompe disease, based on the patient's clinical picture and the biochemical findings. The patient presented unmistakable signs of muscular atrophy in the upper and lower limbs, as well as positive Gowers' sign. Levels of creatinkinase in serum were high. His functional respiratory capacity was diminished. The quantification of the enzymatic activity of acid alpha-glucosidase on filter paper did not show any significant decrease in activity. A molecular genetic analysis revealed the existence of two homozygotic mutations in the gene GAA, c.547-67C>G and c.547-39T>G, both on exon 2 of chromosome 17. According to the human genome database and the review that was undertaken, the changes detected in this patient represent new mutations in the acid alpha-glucosidase gene, GAA. This claim is in agreement with the clinical features and biochemical changes found in the patient. CONCLUSION. A molecular genetic study is mandatory in patients suspected of having this disease.