HMOX1 and Parkinson disease: Furthermore, comparison of HO-1 levels between men and women in the early PD, the advanced PD, and control groups also showed no significant differences [early PD: 2.39 ± 0.75 vs. 2.34 ± 0.60 ng/ml, p = 0.81; advanced PD: 2.33 ± 0.58 vs. 2.10 ± 0.53 ng/ml, p = 0.22; normal controls: 2.18 (1.70, 2.61) vs. 2.07 (1.74, 2.28) ng/ml, p = 0.25; Supplementary Figures 1B–D].