ABCC2 and chronic kidney disease: Carriers of the rs717620-24T variant exhibited high plasma indoxyl sulfate retention in patients with normal renal function, and furthermore, chronic kidney disease patients and patients with normal renal function exhibited indoxyl sulfate and tacrolimus in the ABCC2 normal function (β = −0.740, p = 0.020) and reduced function groups (β = −0.526, p = 0.005), respectively, showing a strong correlation with tacrolimus.