Presentation of multiple sclerosis with comorbid Huntington's disease.

We report a case of Huntington's disease (HD) in a 53-year-old male with multiple sclerosis (MS). The diagnosis of MS met the McDonald criteria and was based on clinical attacks separated in space and time, cerebrospinal fluid, and MRI. The diagnosis of HD was established by DNA testing, family history, and positron emission tomography. While a number of neurologic and autoimmune diseases have been reported with MS, this is the first co-occurrence of HD and MS. Salient features of both disorders are reviewed as well as the importance of obtaining a thorough family history.