Fig. 4From: GCH1 variants contribute to the risk and earlier age-at-onset of Parkinson’s disease: a two-cohort case-control studyMeta-analysis of GCH1 deleterious variants and AAO. a Flowchart showing the search strategy and selection criteria of literature for meta-analysis; b Forest plot of AAO of PD in GCH1 deleterious variant-carriers and non-carriers; c Funnel plot of AAO of PD in GCH1 deleterious variant-carriers and non-carriersBack to article page