Nerve cells in the substantia nigra send fibers to other parts of the brain and release dopamine. Dopamine acts as a chemical messenger allowing communication between the substantia nigra and another area of ​​the brain called the striatum. During operation, this system coordinates fine and gross motor skills. The progressive degeneration of the substantia nigra causes a deficiency of the neurotransmitter dopamine, which leads to the inability to control body movements. Parkinson's disease can also affect emotions and cognition as dopamine also helps regulate emotional responses. About 15% of people with Parkinson's disease have a family history of this disorder. Both cases of Parkinson's disease, familial or non-hereditary, can be caused by mutations in the LRRK2, PARK2, PARK7, PINK1, or SNCA genes. (National Library of Medicine, 2012). Maybe the output in what everyone does. Medicine Network. Alterations in some genes do not appear to cause Parkinson's disease but may change the risk of developing it