The patient's family history was unknown because she had been adopted at birth. After a family bereavement when she was 16 years old, the girl developed an eating disorder that was characterized by fear of weight gain, frequent binge eating, compensatory behaviors, and an abnormally low body weight without amenorrhea. An eating disorder not otherwise specified was diagnosed, and she was treated with cognitive-behavioral therapy. At age 22 she began to complain of instability and disequilibrium. She experienced progressively worsening falls until age 26, when she came to our attention. Neurological examination revealed moderately depressed mood and partial cooperation; mild choreic movements in the extremities, trunk, and face; rare distal myoclonus; reduced eye-head coordination; bilateral brisk reflexes; limb hypotonia and dysmetria; and ataxic gait and balance. Neuropsychological testing revealed a low IQ (WAIS score=52). A blood examination and MRI failed to show clear abnormalities. Genetic testing revealed a CAG expansion (large/short allele: 55/17 triplets) in the IT15 gene. Treatment with pimozide, 2 mg/day, moderately improved her mood.
Over the next 4 years, the patient's motor and cognitive profile progressively deteriorated, and frequent binge eating episodes reappeared.