ALDH1A1 and Parkinson disease: Contrariwise, between the most under-expressed transcript in patients we can point out ALDH1A1, specifically expressed in normal DA neurons and consequently under-represented in PD patients, as shown in several expression studies (see Table 5 and S6 Table); similarly, AGTR1 gene whose trend is consistent with previous evidence showing that the total cellular AGTR1 levels are drastically reduced in surviving dopamine neurons of PD patients [64].