Polyglucosan Body Disease (PBD/APBD)
Adult Polyglucosan Body Disease (APBD)
Inheritance from both parents will result in the disease
Age range at onset:
Adult, typically in 40s
Specialists you may see:
Metabolic disease specialists
The first symptom of APBD is almost always bladder related, leading to near complete loss of bladder control or urinary incontinence. This can happen up to 20 years before other symptoms. Neuropathy is also a common early symptom, including an inability to lift the front of the foot, known as foot drop.
Weakness in the arms and legs can progress to walking difficulties and spasticity. Mild cognitive impairment may occur and some will develop dementia.
Mutations in the GBE1 gene cause this disease. The GBE1 creates a glycogen branching enzyme which is involved in producing a sugar called glycogen, a source of stored energy. When mutations occur, the enzyme creates abnormal glycogen molecules called Polyglucosan bodies. These accumulate and cause damage, particularly to nerve cells, although the reasons for this are not fully understood.
The disease does not always correlate with enzyme activity, so it is not clear how the mutations have caused the disease. In others with this condition, there is no mutation to the GBE1 gene and the genetic cause of the disease is unknown.