This study aims to confirm the findings of Maita et al., who similarly reported no significant differences in DJ-1 serum levels between Japanese PD patients and healthy controls [73]. These inconsistencies are often attributed to variations in sample types (plasma versus serum), differences in measurement methods (e.g., ELISA versus immunoblotting), and potential contamination from red blood cells. The gene discussed is PARK7; the disease is Parkinson disease.