Among the down-regulated genes using the KS test were the transcription factors ATF4 and SREBF1 and genes involved in mitophagy like TOMM7. Interestingly, 10 out of the 13 up-regulated genes in PD monocytes were lower expressed in human microglia, suggesting that there may be a monocyte specific PD-specific transcriptional signature (Table 2). This evidence concerns the gene ATF4 and Parkinson disease.