Adult polyglucosan body disease (APBD) is a rare autosomal recessive neurological disorder with an onset in the fifth to seventh decade of life. The clinical features consist of pyramidal tract signs, peripheral neuropathy with motor deficits, and usually pronounced distal sensory loss predominantly involving the lower limbs, hyper- or hypoactive reflexes, and urinary incontinence due to a neurogenic bladder. Most patients develop dementia, especially in the later stages of the disease. Cerebellar ataxia, extrapyramidal movement abnormalities, and seizures may occur. Some patients have predominantly signs of upper and lower motor dysfunction, prominent wasting of muscles, and fasciculations, suggesting a diagnosis of amyotrophic lateral sclerosis. The clinical course is progressive. The interval between onset of symptoms and death ranges from 3 to 21 years.
CSF protein levels are usually elevated. Neurophys-iological studies show signs of an axonal sensorimo-tor peripheral neuropathy with normal to moderately slowed nerve conduction and signs of denervation in electromyography. SSEP studies show prolonged central conduction times. In the context of the above clinical symptoms, the demonstration of polyglu-cosan bodies in sural nerve biopsy or axillary skin biopsy confirms the diagnosis, especially if they are numerous. In some patients, especially patients of Ashkenazi Jewish ethnic background, deficiency of glycogen branching enzyme has been demonstrated in leukocytes and peripheral nerve biopsies. However, not all patients are deficient in this enzyme despite the otherwise indistinguishable clinical and histo-pathological findings. Prenatal diagnosis is possible in families in which deficiency of glycogen branching enzyme or the underlying genetic defect has been demonstrated.
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