Pompe disease is a lysosomal storage disorder caused by acid alpha-glucosidase deficiency and characterized by progressive muscle weakness. Enzyme replacement therapy (ERT) has ameliorated patients' perspectives, but reversal of skeletal muscle pathology remains a challenge. We studied pretreatment biopsies of 22 patients with different phenotypes to investigate to what extent fiber-type distribution and fiber-type-specific damage contribute to clinical diversity. Pompe patients have the same fiber-type distribution as healthy persons, but among nonclassic patients with the same GAA mutation (c.-32-13T>G), those with early onset of symptoms tend to have more type 2 muscle fibers than those with late-onset disease. Further, it seemed that the older, more severely affected classic infantile patients and the wheelchair-bound and ventilated nonclassic patients had a greater proportion of type 2x muscle fibers. However, as in other diseases, this may be caused by physical inactivity of those patients.
van den Berg, L. E., Drost, M. R., Schaart, G., de Laat, J., van Doorn, P. A., van der Ploeg, A. T., & Reuser, A. J. (2013). Muscle fiber-type distribution, fiber-type-specific damage, and the Pompe disease phenotype. Journal of Inherited Metabolic Disease, 36(5), 787-794. https://doi.org/10.1007/s10545-012-9541-7