ABCG2 and Wilson disease: As for ABC transporters, the mRNA expression levels were significantly increased in WD group in case of ABCB1 (U = 32; N = 27; p = 0.038), ABCC1 (U = 1; N = 27; p = 2 × 10–4) and ABCC4 (U = 0; N = 27; p = 1 × 10–4).