S100A4 level was significantly higher in patients with AE of IP (median, 48.21 ng/mL; IQR, 30.89–69.17 ng/mL) than in patients without AE of IP (5.00 ng/mL; IQR, 1.17–17.04 ng/mL; P < 0.001). This evidence concerns the gene S100A4 and incontinentia pigmenti.