The median serum HO-1 level in IP patients having an AE was 53.5 ng/mL; this value was significantly higher than those in IP patients not having an AE (24.1 ng/mL, p < 0.001) and in control subjects (31.7 ng/mL, p < 0.001) (Figure 1(a)). This evidence concerns the gene HMOX1 and incontinentia pigmenti.