Epidemiology

Pompe disease is a rare disorder. In the absence of large-scale epidemiological studies, the current estimates on incidence and prevalence have generally been extrapolated from reports of carrier frequency, or the number of healthy individuals who possess one defective copy of the GAA gene.

Incidence

Current estimates put the overall disease incidence at 1 in 40,000 live births. This figure is supported by two studies, one conducted in The Netherlands (n=3,000) and the other in New York (n=928).^{1, 2}

A 1999 Dutch study reported the results of testing 3,000 newborns for three different mutations of Pompe disease common in that population.¹ Based on the carrier frequency derived, the estimated overall incidence is found in the following table.The authors concluded that their findings were two to four times higher than what had previously been suggested.¹

Pompe Disease Type	Incidence per Births (95% CI)
Infantile onset	1/138,000 (1/43,000 to 1/536,000)
Late onset	1/57,000 (1/27,000 to 1/128,000)
All Pompe	1/40,000 (1/18,000 to 1/100,000)

CI = Confidence interval. References 1, 2

A year earlier, similar findings were published by researchers in New York.² After testing 928 randomly selected individuals for seven mutations, the authors determined a carrier frequency of 1 in 100, and from that, an estimated incidence of 1 in 40,000.

Since 25% of the study subjects were African American, the results have since been reexamined by another author to predict a disease frequency of 1 in 31,000 for the infantile-onset form in African Americans, the highest for any ethnic group to date.³ In comparison, the recalculated results showed an estimated incidence of between 1 in 60,000 (late-onset form) and 1 in 100,000 (infantile-onset form) for Caucasians.

Studies have also shown that there are more cases of infantile-onset Pompe disease in Southern China and Taiwan.³

Prevalence

As with any rare disease, it is difficult to know exactly how many people are actually affected. Assuming a worldwide incidence of 1 in 40,000, it can be extrapolated that the worldwide prevalence may be somewhere between 5,000-10,000.

References

1. Ausems MG, Verbiest J, Hermans MP, et al. Frequency of glycogen storage disease type II in The Netherlands: implications for diagnosis and genetic counseling. Eur J Hum Genet 1999 Sep; 7(6): 713-6.

2. 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.

3. Hirschhorn, Rochelle and Arnold J. J. Reuser. Glycogen Storage Disease Type II: Acid Alpha-Glucosidase (Acid Maltase) Deficiency. In: Scriver C, Beaudet A, Sly W, Valle D, editors. The Metabolic and Molecular Bases of Inherited Disease. 8th Edition. New York: McGraw-Hill; 2001; 3389-3420.