As shown in Fig. 3, integrated optical density (IOD) values for TH-positive nerve fibers and numbers of TH-positive neurons in the SNpc were significantly lower in the PD group than in the control group (0.99 ± 0.16 vs 0.34 ± 0.43, P < 0.01, F = 73.015; 1.04 ± 0.22 vs 0.19 ± 0.07, P < 0.001, F = 65.333). The gene discussed is TH; the disease is Parkinson disease.