We observed a clear difference in the gene expression profile between the PD group (Fig. 4A, red squares) and HC group (Fig. 4A, blue squares), showing a decrease in the IGF2 levels and the expression of genes from the initial step of the autophagy pathway, excepting LC3B and RUBICON. Next, we evaluated the most predominantly variables (IGF2 and autophagy gene expression) associated with PD patients using a PCA, a statistical method that allows the association of the profile of gene expression for each patient71–73. The gene discussed is IGF2; the disease is Parkinson disease.