Istradefylline, a selective A2AR antagonist (Ki = 12.4 nM),8 was then launched in Japan in 2013 as an adjunct to levodopa to alleviate off episodes in PD and was subsequently approved by the US Food and Drug Administration in 2019.9, 10 Currently, once‐daily oral administration of istradefylline 20 or 40 mg is recommended. The gene discussed is ADORA2A; the disease is Parkinson disease.