LRRK2 and Parkinson disease: In an effort to avoid these potential on-target side effects, we and others recently have undertaken the development of brain-penetrant, highly selective G2019S-LRRK2 kinase inhibitors to test the hypothesis that such precision therapeutics might bring similar benefits with less side effects—especially when administered over years to decades—to people with PD driven by G2019S-LRRK2 (43–46).