R6/2 transgenic mice display progressive phenotype reminiscent of Huntington Disease (HD) in humans, including choreiform-like movements, involuntary stereotypic movements, tremor, and epileptic seizures, as well as non motor symptoms, including unusual vocalization. Frequent urination and loss of body weight and muscle bulk occurs with disease progression. Neurological developments include Neuronal Intranuclear Inclusions, which contain both the huntingtin and ubiquitin proteins. Onset of HD symptoms occurs between 15 and 21 weeks of age. This line is transgenic for the 5' end of the human HD gene carrying approximately 120 +/- 5 (CAG)repeat expansions.