However, because the number of patients in each group was small and nonoptimal for ROC analysis, the obtained characteristics of clusterin as a diagnostic and differential marker in PD should be interpreted with caution, especially in light of the fact that a larger study has not confirmed clusterin elevation at all [169], and all three studies by Přikrylová Vranová et al. [173,174,175] seem to have highly overlapping cohorts and should rather be treated and weighted as one. This evidence concerns the gene CLU and Parkinson disease.