While DKK1 is a prognostic marker for cancer progression (Kandimalla et al., 2017), it is also elevated in various neurological disorders including stroke, Parkinson's and AD (Shou et al., 2002; Caricasole et al., 2004; Scott and Brann, 2013; Purro et al., 2014). This evidence concerns the gene DKK1 and Parkinson disease.