Adult Polyglucosan Body Disease (APBD) is a neuromuscular, adult-onset form of glycogen storage disease type IV (GSD IV).
APBD symptoms include numbness and tingling in feet/legs and hands/arms (peripheral neuropathy), progressive muscle weakness and stiffness (spasticity), increasing difficulty starting or stopping the flow of urine (neurogenic bladder), fatigue, and cognitive difficulties.
Individuals with APBD can begin experiencing symptoms as early as age 35. They eventually lose the ability to walk, stand, stay continent, stay awake, perform at work, and socialize. They are robbed of nearly every aspect of their independent adult lives.
APBD is pan-ethnic, but is diagnosed most frequently in people of Ashkenazi Jewish ancestry. It is frequently misdiagnosed as multiple sclerosis, cerebral small vessel disease, amyotrophic lateral sclerosis, or peripheral neuropathies.
APBD is one of several forms of GSD IV, all of which are caused by autosomal recessive mutations in the glycogen branching enzyme (GBE1) gene. The glycogen branching enzyme helps build well-branched sugar storage molecules called glycogen. Insufficient levels of the enzyme result in the accumulation of poorly branched glycogen. This poorly branched glycogen forms clumps called polyglucosan bodies that build up in muscle, nerve, and various other tissues in the body and drive APBD progression.