SHH and Parkinson disease: Positive modulation of the Shh signaling pathway has been proposed as a potential therapeutic approach for Parkinson's disease (Gonzalez-Reyes et al. 2012; Malave et al. 2021) and for demyelinating diseases (Loulier et al. 2006; Ferent et al. 2013b; Porcu et al. 2015; Samanta et al. 2015; Del Giovane et al. 2022).