Adult polyglucosan body disease (APBD) is a rare genetic glycogen storage disorder caused by an inborn error of metabolism. Symptoms can emerge any time after the age of 30; early symptoms include trouble controlling urination, trouble walking, and lack of sensation in the legs. People eventually develop dementia. A person inherits loss-of-function mutations in the GBE1 gene from each parent, and the lack of glycogen branching enzyme (the protein encoded by GBE1) leads to buildup of unbranched glycogen in cells, which harms neurons more than other kinds of cells. Most people first go to the doctor due to trouble with urination. The condition is diagnosed by gathering symptoms, a neurological examination, laboratory tests including genetic testing, and medical imaging. As of 2015 there was no cure or treatment, but the symptoms could be managed. People diagnosed with APBD can live a long time after diagnosis, but will probably die earlier than people without the condition. Signs and symptoms
Adult polyglucosan body disease is a condition that affects the nervous system. People with this condition have problems walking due to reduced sensation in their legs (peripheral neuropathy) and progressive muscle weakness and stiffness (spasticity). Damage to the nerves that control bladder function (neurogenic bladder) causes progressive difficulty in controlling the flow of urine. About half of people with adult polyglucosan body disease experience dementia. Most people with the condition first complain of bladder issues.People with adult polyglucosan body disease typically first experience signs and symptoms related to the condition between ages 30 and 60.
Examination of tissue biopsied from the sural nerve under a microscope can reveal the presence of polyglucosan bodies. There will also be white matter changes visible in a magnetic resonance imaging scans. Classification
Adult polyglucosan body disease is an orphan disease and a glycogen storage disorder that is caused by an inborn error of metabolism, that affects the central and peripheral nervous systems.The condition in newborns caused by the same mutations is called glycogen storage disease type IV. Prevention
APBD can only be prevented if parents undergo genetic screening to understand their risk of producing a child with the condition; if in vitro fertilization is used, then preimplantation genetic diagnosis can be done to identify fertilized eggs that do not carry two copies of mutated GBE1. Management
As of 2015 there was no cure for APDB, instead symptoms are managed. There are various approaches to managing neurogenic bladder dysfunction, physical therapy and mobility aids to help with walking, and dementia can be managed with occupational therapy, counseling and drugs. Presently a number of promising research initiatives are underway in universities and hospitals in the United States, Canada, and Israel. These studies are in need of funding but due to the small number of known cases both research funding and participation is small. It is estimated that there are upwards of 12,000 cases in the United States, most of which are undiagnosed.