Gene expression analysis by qPCR revealed that APP is significantly upregulated in blood of Parkinson's disease patients compared to healthy controls in the HBS cohort (Mean ± SEM; 4.96±0.98, p = 0.01) and PROBE study (Mean ± SEM; 5.11±1.0, p = 0.01) (Figure 4 A and B). The gene discussed is APP; the disease is Parkinson disease.