ALDH1A1 and Parkinson disease: A protective function of Aldh1a1 in DA neurons has been reported in several studies (Anderson et al., 2011; Wey et al., 2012; Liu et al., 2014); moreover, reduced Aldh1a1 expression and the loss of Aldh1a1-positive DA neurons has been observed in post-mortem brain sections from PD patients (Liu et al., 2014).