MANF and Parkinson disease: Early functional studies about MANF are focused on its role in Parkinson’s disease (PD), as genetic knockdown or knockout of manf in zebrafish or fruit fly lead to defective development of the dopamine system (Palgi et al., 2009; Chen et al., 2012), and administration of purified MANF protein or viral vectors expressing MANF has beneficial effects in both cellular and animal models of PD (Petrova et al., 2003; Zhou et al., 2006; Voutilainen et al., 2009; Hao et al., 2017).