Adult polyglucosan body disease
Rare genetic disorder causing nerve damage from abnormal glycogen buildup.
Adult polyglucosan body disease (APBD) is a rare monogenic glycogen storage disorder (GSD type IV) caused by an inborn error of metabolism. It affects the nervous system, with symptoms typically emerging between ages 30 and 60, including bladder control issues, walking difficulties, and muscle weakness. The condition results from loss-of-function mutations in the GBE1 gene inherited from both parents, leading to accumulation of abnormal glycogen (polyglucosan) that damages neurons.
- prevalence
- Approximately 160 reported cases worldwide; ~1/16,000 in Ashkenazi Jewish population
Lore & Background
Adult polyglucosan body disease is caused by mutations in the GBE1 gene, which encodes the glycogen branching enzyme. The most common pathogenic variant, p.Tyr329Ser (c.986A>C), is particularly prevalent among individuals of Ashkenazi Jewish descent. The lack of functional enzyme leads to production of polyglucosan—long, unbranched chains of glucose—that accumulate in cells, especially neurons, impairing their function. All known pathogenic GBE1 mutations reduce enzyme activity, and no APBD cases without a GBE1 mutation have been established.
Reader's Guide
APBD is significant as a rare neurodegenerative disorder that highlights the vulnerability of neurons to metabolic errors. Its classification as both an orphan disease and a glycogen storage disorder (GSD IV) underscores the overlap between adult and pediatric forms. Diagnosis relies on genetic testing, skin biopsy for enzyme activity, and MRI showing white matter changes. As of 2025, no cure exists, but symptom management—including bladder care, physical therapy, and dementia support—can improve quality of life. The condition's prevalence is highest in Ashkenazi Jewish populations, and prevention is possible through genetic screening and preimplantation diagnosis. Research includes a transgenic mouse model developed in 2015, and the Adult Polyglucosan Body Disease Research Foundation funds further studies.
Did You Know?
- About half of people with APBD experience dementia.
- The most common GBE1 mutation in APBD is p.Tyr329Ser (c.986A>C), especially in Ashkenazi Jewish individuals.
- Polyglucosan bodies can also accumulate in liver, skeletal muscles, and heart in children with GSD IV.
- As of 2020, only about 160 cases of APBD had been reported in medical literature.
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