The most used medication for PD treatment was levodopa associated with adopa decarboxylase inhibitor in 92.5% of cases, followed by dopamine agonists in60%, amantadine in 15%, type-B monoamine oxidase (MAOB) inhibitors in 12.5%,and catechol-O-methyltransferase (COMT) inhibitors in 5%. The gene discussed is MAOB; the disease is Parkinson disease.