International Pompe Association

Dr. M.G.E.M. Ausems
Department of Medical Genetics, University Medical Centre
Utrecht, the Netherlands

Introduction

Glycogen storage disease type II (or GSD II, acid maltase deficiency, Pompe’s disease) has been estimated to be a rare disease. The usually quoted figure of 1 in 100.000 for the frequency of GSD II is not supported by strong data. The first retrospective studies on the frequency of the disease were limited to infantile GSD II and indicated that the frequency of infantile GSD II may range between 1/125.000 and 1/548.000(1,2).

The numbers

In a recent study from Australia including early and late-onset phenotypes the estimated birth prevalence of GSD II was 1 in 146.000 (3). We previously predicted the theoretical frequency of GSD type II on the basis of mutation analysis in an unselected sample of over 3000 Dutch new-borns (4). Based on the calculated carrier frequencies, the predicted frequency of GSD II was 1 in 40.000, divided over 1 in 138.000 for infantile GSD II and 1 in 57.000 for adult GSD II. A recent study on the carrier frequency in the United States also indicated a disease frequency of 1 in 40.000 (5).

The apparent discrepancy of figures could be explained by ‘under-diagnosis’ of the disease. To investigate whether GSD II is under-diagnosed, we identified all pre- and postnatal diagnoses in the Netherlands over the period 1972 through 1996. Based on the number of diagnoses we calculated the birth prevalence of the various phenotypes and compared these data with the calculated frequencies from our previous study based on mutation screening. In addition, we compared the medical discipline and professional setting (university or general hospital) of the clinicians referring their patients for diagnosis. Our results suggest that the world wide frequency of GSD II must be higher than 1 in 100.000 and that the birth prevalence of adult GSD II is two times higher than that of infantile GSD II.

References

  1. Loonen MCB. The variability of Pompe’s disease. A clinical, biochemical and genetic study of glycogen storage disease type II. Academic Thesis. 1979.
  2.  Schaub J, Bayerl P. Incidence of glycogen storage disease in the German Federal Republic. Z. Kinderheilk. 1975; 120:79-85.
  3. Meike PJ, Hopwood JJ, Clague AE, Carey WF. Prevalence of lysosomal storage disorders. JAMA 1999; 281: 249-254.
  4. Ausems MGEM, Verbiest J, Herman MMP, et al. The frequency of Glycogen Storage Disease type II in the Netherlands: implications for diagnosis and genetic counselling. Eur J Hum Genet in press.
  5. Martiniuk F, Chen A, Mack A et al. Carrier frequency for glycogen storage disease type II in New York and estimates of affected individuals born with the disease. Am J Med Genet 1998; 79:69-72.