Rasagiline is a selective, irreversible, monoamine oxidase B inhibitor [11] that was approved in Europe in 2005 [12], in the US in 2006 [13], and most recently in Japan in 2018 [14], as a monotherapy in early PD and as an adjunct therapy to levodopa in PD with motor fluctuations. The gene discussed is MAOB; the disease is Parkinson disease.