Activity of DPPIV in serum, % of CD26+ lymphocytes and % of CD26+ white blood cells, mean fluorescence intensity (MFI) of CD26 expression on lymphocytes and % of lymphocytes in healthy controls, people with vitiligo, patients with melanoma, and in patients with other malignant skin tumors and benign changes of the skin. This evidence concerns the gene DPP4 and vitiligo.