GCH1 and Parkinson disease: Previously, we have replicated PRKN (Guo et al., 2008), PINK1 (Guo et al., 2008; Tang et al., 2006), PARK7 (Guo et al., 2008; Tang et al., 2006), ATP13A2 (Guo et al., 2008), PLA2G6 (Shi et al., 2011), CHCHD2 (Liu et al., 2015), RAB39B (Kang et al., 2016), TMEM230 (Yan et al., 2017), GCH1 (Xu et al., 2017), and other genes (Tian et al., 2012; Yang et al., 2019) in patients with PD in China.