GNRH1 and Parkinson disease: Other functional pathways relevant for PD included angiogenesis (linked to the formation of new blood vessels), fibroblast growth factor (FGF; among multiple functions, FGF has been shown to facilitate the formation of functional dopaminergic neurons17) and gonadotropin-releasing hormone receptor (GnRH; recently reported as a modulator of dopaminergic cell activity18).