Adult Polyglucosan Body Disease (APBD)
What is Adult Polyglucosan Body Disease (APBD)?
Adult Polyglucosan Body Disease (APBD) is a rare disorder that affects the nervous system. A characteristic symptom of this disease is problems walking because of a reduced sensation in the legs. It is very progressive, meaning that symptoms worsen as time goes on.
APBD occurs due to a deficiency of a glycogen-branching enzyme. Without enough of this enzyme, substances called polyglucosan bodies accumulate in tissues throughout the body. Polyglucosan bodies are substances in the body composed of large, sugar-based molecules that are difficult to dissolve. When these bodies amass, they block the actions of neurons, which can cause problems in many parts of the body.
People typically start showing symptoms between ages 30 and 60. While the exact prevalence is unknown, it is thought to affect men and women equally. Literature suggests it is more likely to affect people of Ashkenazi Jewish ancestry.
What are the symptoms of APBD?
- Problems walking
- Sensory loss in the legs
- Muscle weakness and stiffness that gets progressively worse
- Difficulty controlling the flow of urine (neurogenic bladder) that gets progressively worse
- Mild decline in intellectual function, or dementia
Neurogenic bladder will often be the first symptom, initially appearing as an increased need to urinate and then worsen to loss of bladder control.
What causes APBD?
APBD is usually caused by a mutation in the GBE1
gene, though in some cases the cause has been unknown. Human traits are inherited from a person’s father and mother; each one contributes a copy of a gene, which interacts with the other copy. APBD is inherited in an autosomal recessive pattern, which means that both parents need to pass down a copy of the mutated gene for the condition to occur.
How is APBD diagnosed?
APBD can be diagnosed using the following procedures:
- A thorough clinical evaluation
- Recording of patient history
- Finding characteristic symptoms
- Electron and light microscopy, which are direct examinations of tissue, conducted by a pathologist
- Molecular genetic testing
What are the treatments for APBD?
APBD treatment is supportive and focuses on treating symptoms. It includes:
- Antispasmodic medications for people with neurogenic bladder
- Use of a catheter to drain urine from the bladder
- Physical therapy
- Occupational therapy
- Dementia treatment
- Genetic counseling
- Devices to help with physical activities, such as wheelchairs, braces, and other supports
Where can I find out more about APBD?