Clinical Features of Adaptor Protein 3 Subunit B2 Autoimmune Disease–Related Ataxias

Adaptor protein 3 subunit B2 (AP3B2) is a neuron-restricted protein in dendrites and axons that directs proteins from endosomes to synaptic vesicles. Ten patients with AP3B2 antibodies were identified retrospectively by a pattern of diffuse neural synaptic staining, nine of whom had clinical details available.

Median age at onset was 42 years (range, 24–58); 60% were women; onset was subacute with a rapidly progressive disease course. Symptoms included a myeloneuropathy in three patients, a peripheral sensory neuronopathy in two, cerebellar ataxia in two, and spinocerebellar ataxia in two. All patients reported a gait disturbance. Some had dysarthria, vertigo, dizziness, tremor, gastrointestinal dysmotility, and bladder dysfunction. Two pati…