The hallmark pathology of Parkinson’s disease is the damage and death of dopamine producing neurons in the brain. Dopamine plays a role in controlling movement, cognition, learning, and mood, explaining the dementia and difficulty with motor control exhibited by patients with deficits in the production of this key neurotransmitter. The a-synuclein gene was one of the first to be implicated in this disease. It produces a protein that can, in certain circumstances, aggregate to form bundles that are a major component of Lewy bodies—fibers that disrupt normal cell processes. Recently researchers have discovered other mechanisms by which this protein damages or kills dopamine-producing neurons, as well as other genes that may also play a role in driving the disease.