Adult polyglucosan body disease (APBD) is a rare monogenic glycogen storage disorder (GSD type IV) caused by an inborn error of metabolism.

People with this condition have problems walking due to reduced sensation in their legs (peripheral neuropathy) and progressive muscle weakness and stiffness (spasticity).

[2] People with adult polyglucosan body disease typically first experience signs and symptoms related to the condition between ages 30 and 60.

This enzyme is involved in the production of a complex sugar called glycogen, which is a major source of stored energy in the body.

These abnormal glycogen molecules, called polyglucosan bodies, accumulate within cells and cause damage.

[1] Some mutations in the GBE1 gene that cause adult polyglucosan body disease do not result in a shortage of glycogen branching enzyme.

Examination of tissue biopsied from the sural nerve under a microscope can reveal the presence of polyglucosan bodies.

[4][5] The condition in newborns caused by the same mutations is called glycogen storage disease type IV.