They found no difference in levels and diurnal rhythm of leptin in patients with PD and concluded that weight loss and neurodegenerative pathways in PD have no association with adipokine secretion.   21  Ozdilek and Kenangil showed that leptin levels correlated with age, gender, and BMI, but disease duration and clinical severity had no effect in leptin concentration. The gene discussed is LEP; the disease is Parkinson disease.