Pompe Disease

Pompe disease is a rare genetic disorder. It is caused by a deficiency in the enzyme acid alpha-glucosidase (GAA). This is needed to break down glycogen. That is a stored form of sugar used for energy. The build-up of glycogen causes progressive muscle weakness throughout the body. It affects various body tissues, particularly in the heart, skeletal muscles, liver, and nervous system. Children have a 1 in 4 chance of inheriting the disease when both parents carry the abnormal gene. This disease is also known as infantile acid maltase deficiency and type 2 glycogen storage disease. It is estimated to occur in about 1 in 40,000 births.

Pompe disease has three forms. They are defined by age of onset and progression of symptoms.

  • Infantile or early onset. This is noticed shortly after birth. Symptoms include severe lack of muscle tone, weakness, and enlarged liver and heart. Mental function is not affected. Development appears normal for the first weeks or months. But it slowly declines as the disease progresses. Swallowing may become difficult. Also, the tongue may protrude and become enlarged. Most children die from respiratory or cardiac complications before 2 years of age.

  • Juvenile onset. Symptoms appear in early to late childhood. They include:

  • Progressive weakness of respiratory muscles in the trunk, diaphragm, and lower limbs.

  • Exercise intolerance. Intelligence is normal. Most patients do not live beyond the second or third decade of life.

  • Adult onset. Symptoms also involve generalized muscle weakness and wasting of respiratory muscles in the trunk, lower limbs, and diaphragm. Many patients report:

  • Respiratory distress.

  • Headache at night or upon waking.

  • Decreased deep tendon reflexes.

  • Proximal muscle weakness, such as difficulty in climbing stairs.

Intellect is not affected. A small number of adult patients live without major symptoms or limitations

TREATMENT

Cardiac and respiratory complications are treated symptomatically. Physical and occupational therapy may be helpful for some patients. Changes in diet may provide temporary improvement. But they will not change the course of the disease. Genetic counseling can provide families with information regarding risk in future pregnancies.