So we assessed PD array databases, initially looking at the genes defining dopaminergic neuron development and phenotype (such as FOXA2, LMX1A, EN1, EN2, SLC18A2, TH, DDC, ALDH1A1, NR4A2, PITX3, SOX6) as well as more generic markers of a neuronal phenotype (SNCA, SYP, FABP7, GCH1, PTS, TUBB3, MAP2). The gene discussed is GCH1; the disease is Parkinson disease.