Further Elisa analysis showed that serum levels of HO‐1 and its reactive products including bilirubin, CoHb and iron (Fe2+) in vitiligo significantly reduced compared with healthy controls (HO‐1: 37.75 ± 21.43 pg/mL vs 17.43 ± 14.84 pg/mL, P = .0013; Tbil: 12.63 ± 6.36 pg/mL vs 6.74 ± 4.35 pg/mL, P = .0011; CoHb: 346.48 ± 64.92 pg/mL vs 252.70 ± 77.90 pg/mL, P = .0002; Fe2+: 11.06 ± 4.18 μmol/L vs 5.51 ± 3.47 μmol/L, P < .001) (Figure 4C‐I). This evidence concerns the gene HMOX1 and vitiligo.