Huntington's disease is a neurodegenerative disorder of the brain that is caused by the mutation of the gene which produces a protein called huntingtin (htt). The mutation is based on the continuous repetition of the trinucleotide CAG which in turn makes the protein toxic for the brain cells. As a result neurons which contain the mutant protein begun to atrophy. The loss of those brain cells can cause many problems to the patients, even death. The aim of this paper is to report the problems caused to the brain by the mutant protein, specifically in the area of basal ganglia, the area that is the most affected by the disease, as well as the symptoms and metabolic changes to which the patient is subjected. Finally, the summary of the methods for a more timely and accurate diagnosis of the disease is based on these changes in order to simplify and facilitate the lives of inflicted people by means of the administration of the appropriate treatment.