This is consistent with other previous isolated reports of adult-onset parkinsonism in GCH1 mutation carriers with abnormal nigrostriatal imaging (features summarized in Table 1) (Kikuchi et al., 2004; Hjermind et al., 2006; Eggers et al., 2012; Ceravolo et al., 2013). Here, GCH1 is linked to Parkinsonism.