What is APBD or Adult polyglucosan body disease?

APBD is an orphan disease and glycogen storage disorder that affects the nervous system.

What Are the Symptoms?

Symptoms usually appear between the ages of 30 and 60 and can include:

  • Numbness and tingling in the legs
  • Spasticity
    • The symptoms above can cause an unsteady gait, poor balance, and an increased risk of falling.
  • Difficulty starting or stopping the flow of urine caused by damage to the nerves that control bladder function
  • About 50% of people with APBD will experience dementia

How Do You Get APBD?

APBD is an autosomal recessive disorder and is caused by mutations in the GBE1 gene. This gene provides instructions for making the glycogen branching enzyme which is involved in the production of a complex sugar called glycogen. Glycogen is a major source of stored energy in the body. The GBE1 gene mutations that cause this disorder result in a deficiency of this enzyme, which leads to the production of abnormal glycogen molecules. These molecules accumulate within cells and cause damage. Nerve cells seem to be particularly vulnerable to this damage in people with this disorder, which leads to impaired neuronal function.

How Is APBD Diagnosed?

It is diagnosed through evaluation of the symptoms the individual is experiencing, a neurological exam and genetic testing. A skin biopsy can show if the person is making sufficient amounts of functional glycogen branching enzyme. White matter changes will also be visible in an MRI.

Is There a Treatment?

There is no cure so symptoms are managed through working with urology physical therapy, occupational therapy, counseling and medication.

Helpful Resources

Genetics Home Reference

Leukodystrophy Care Network