Huntington's disease (HD) is a genetic disorder characterized by movement disturbances, psychiatric symptoms, and cognitive impairment resulting in a subcortical dementia. It is an autosomal dominant neurodegenerative disease with almost complete penetrance. An increased number of CAG repeats in the 5’ region of the IT15 gene on chromosome 4 is believed to be the responsible mutation. CAG expansion beyond 35 repeats is associated with the expression of HD.

A description of the psychiatric symptoms of Huntington's disease through a possible case.

A 28 year-old, female, was admitted for injury and grandeur delusions, suspicion an mania that had started in the last two weeks. Grandmother and great grandmother diagnosed with Huntington's disease. Transcranial magnetic resonance seemed to show a descent on the peak of the N-Acetylaspartate neuronal marker. Genetic test shower 27 repeats of the CAG, that is, intermediate risk. Olanzapine was started up to 20 mg per day and carbamazepine was started up to 600 mg per day. She had a progressive clinical improvement and in one month was discharged.

The diagnosis of HD is based upon presence of the typical clinical features and a family history of the disease. with the availability of genetic molecular testing, all suspected HD cases can be easily confirmed.

In our case report, because of the medium-risk, genetic advice will be necessary, due to the probability of transmiting the illness onto the descendants, as well as a follow-up to predict its reappearing.