Pearls & Oy-sters: Family history of Huntington disease disguised a case of dentatorubral-pallidoluysian atrophy

earlsAdditional neurologic signs such as mild cerebellar ataxia and uncommon EEG and MRI findings in patients with generalized chorea and a positive family history should prompt clinicians to also consider Huntington disease–like syndromes.Oy-stersA self-reported positive family history for Huntington disease may disguise dentatorubral-pallidoluysian atrophy, an autosomal dominantly inherited trinucleotide repeat expansion disorder that is very rare outside of Asian countries.Mild to moderate cerebellar ataxia may be overlooked in the presence of dominating generalized chorea.Case reportA 42-year-old woman of Caucasian ancestry presented with an episode of acute paranoid psychosis, an 8-month history of slowly progressive generalized choreoathetosis, gait and speech disturbance, as well as cognitive impairment. Her choreoathetosis remarkably improved due to olanzapine, and subsequently, cerebellar signs became obvious upon neurologic examination (video, http://links.lww.com/WNL/A45). Cranial MRI revealed moderate atrophy of the vermal part of the cerebellum but not of the caudate nucleus. EEG showed runs of frontal intermittent high-amplitude delta activity. The patient reported a positive family history for Huntington disease (HD) (figure). Genetic testing was negative twice for HD and spinocerebellar ataxias (SCAs) including SCA17, but revealed 59 ± 2 CAG repeats (<48) in the ATN1 gene confirming the first German case of adult-onset dentatorubral-pallidoluysian atrophy (DRPLA).1,2