NRTN and Parkinson disease: Indeed, TH-staining constituted a relatively large proportion (Fig. 4C, D, F and G) of the NRTN-immunohistochemical footprint, whereas there was a comprehensive loss of TH-positive fibres (Fig. 4H) in areas without detectable NRTN staining similar to Parkinson’s disease controls (Fig. 4J), as we have previously reported (Bartus et al., 2011a, 2015; Kordower, 2016).