Hi Jane,

I was not aware of this one so I thought I'd put a brief introduction about this disease to add to this post. It came from: About Pompe Disease

About Pompe Disease

Pompe disease is a rare and debilitating muscle disease affecting both children and adults. The infantile-onset form of the disease generally manifests within a few months of birth while the late-onset form appears anytime during childhood or adulthood in a more gradual fashion. Both types are generally characterised by progressive muscle weakness and breathing difficulty, but the severity of the disease can vary widely depending on the age of onset and the extent of organ involvement. In the infantile-onset form, patients typically display a markedly enlarged heart.

The Cause

People born with Pompe disease have an inherited deficiency of an enzyme known as acid alpha-glucosidase (GAA). Enzymes, which are protein-based molecules within cells, trigger biochemical reactions in the body. In a healthy person with normal GAA activity, this particular enzyme would assist in the breakdown of glycogen, a complex sugar molecule stored within a compartment of the cell known as the lysosome. But in Pompe disease, the GAA activity may be dramatically reduced, dysfunctional, or non-existent, resulting in an excessive accumulation of glycogen in the lysosome.

Eventually, the lysosome may become so clogged with glycogen that normal cellular function is disrupted and muscle function is impaired. In later stages of the disease, the lysosomes may even rupture, releasing glycogen into the rest of the cell. Although there is glycogen storage in the cells of multiple tissues, heart and skeletal muscles are usually the most seriously affected.