Glycogenosis type II (morbus Pompe, glycogen storage disease type II, GSD II) is a generalized glycogenosis with lysosomal storage of glycogen, caused by deficiency of acidic -1,4-glucosidase. There are two basic phenotypes. The predominating clinical sign in the classical infantile form is a hypertrophic cardiomyopathy, whereas subjects with classical juvenile and adult form suffer from myopathy. The prognosis is unfavourable. The patients die of cardiopulmonary failure, children with the infantile form usually during the first year of life, patients with the juvenile and adult form mostly in the 2nd to 4th decade. The activity of muscular enzymes in serum is elevated and there is demonstrable intralysosomal storage of glycogen in tissues. The heredity is of autosomal recessive type with the incidence 1:40,000 to 1:100,000; the gene for the disease (GAA gene) is localized on chromosome 17q23. In the years 1973 - 2002 the authors diagnosed GSD II in 14 patients belonging to 11 families, six of them until 1993 on the basis of histochemical and electron microscopic examination of tissues. The other 8 patients were diagnosed since 1994, four of them by detecting the deficiency of acidic -1,4-glucosidase in leukocytes and three in cultivated fibroblasts, two patients were diagnosed by histochemical and electron microscopic examination. In 11 cases a classical infantile Pompe’s disease was established, the juvenile form occurred in three patients. The contribution is devoted to patients with classical infantile Pompe’s disease. Three female patients with the juvenile GSD II coming from two families are presently examined in detail. In the families of some patients with GSD II, molecular-genetic studies of the gene for GSD II (the GAA gene) are presently under way, the results being subject to another publication.

        Key words: glycogenosis type II, infantile form (morbus Pompe) in the Czech and Slovak population