Compare and contrast Parkinson's disease and Huntington's disease. Huntington's disease is caused by a faulty gene on chromosome. The gene, which produces a protein called Huntingtin. This leads to a nerve damage resulting in damage ot nerves and nerve cells in th bran icludiing the basal ganglia and cerebral cortex. The result of this is that the person detoirtes in the gradual physical, mental and emotional changes. Parkinson's occurs as result of a loss of nerve cells in the part of the brain known as the substantia nigra. These cells are responsible for producing a chemical known as dopamine, which allows messages to be sent to the parts of the brain that co-ordinate movement. With the depletion of dopamine-producing cells, these parts of the brain are unable to function normally.