Detection of Pompe Disease in Adult Patients With Myopathies of Uncertain Origin or With Asymptomatic Hyper-CK-emia

Lysosomal storage disorders are inborn errors of metabolism characterized by defects in lysosomal function. Lysosomes contain acid hydrolases whose function is to break down complex molecules in the cell into simpler ones. A deficiency in the activity of any of these enzymes results in the progressive accumulation of substances that cause a storage disease.

Pompe disease is a progressive muscle disease that is often fatal, caused by a deficiency of lysosomal alpha glucosidase (also known as acid maltase) activity. This leads to the accumulation of glycogen in many tissues, most notably in skeletal and cardiac tissues and in muscle tissue. It is therefore also a glycogen storage disease (type II).

It is inherited in an autosomal recessive manner and was the first lysosomal storage disease to be identified. The incidence rate varies by geographic area and ethnic group, and is estimated to be between 1/300,000 to 1:40,000.

It has a broad clinical spectrum that varies with respect to age of onset, rate of progression and extent of organ involvement.

The adult onset form can occur between the second and sixth decades of life as a form of proximal myopathy, predominantly in the pelvic girdle area. Sometimes the first symptoms are shortness of breath and diaphragm weakness which herald progressive proximal muscle weakness. The heart and liver are not affected.