Adult polyglucosan body disease: ultrarare but commonly misdiagnosed.

Adult polyglucosan body disease is a rare genetic condition caused by biallelic pathogenic variants in GBE-1 gene. Affected patients typically have urinary dysfunction, progressive gait disturbance and cognitive impairment. We report a 63-year-old woman with urinary incontinence, walking difficulty and episodes of forgetfulness. She had symmetrical limb weakness with upper motor neurone signs, distal sensory loss and a broad-based ataxic gait. MR scans of the brain and spine showed white matter changes with cerebellar and spinal cord atrophy. Sural nerve biopsy identified intra-axonal polyglucosan bodies. A multigene panel test identified a GBE-1 pathogenic variant, confirming the diagnosis of adult polyglucosan body disease. This case emphasises the importance of considering rare genetic disorders in people with autonomic dysfunction, mixed upper and lower motor neurone signs, peripheral neuropathy and cognitive impairment.