In contrast to the aforementioned studies, a clinical study including 624 patients showed increased BDNF levels in patients with PD28, suggesting that elevated levels of BDNF may be involved in inflammation progression29, a discrepancy that may be attributed to the inherent complexities of observational studies and factors such as the stage of PD and the effects of pharmacological interventions. The gene discussed is BDNF; the disease is Parkinson disease.