CKD-associated pruritus has also been linked with heightened concentrations of β2-microglobin (a pruritogenic factor); upregulation of kappa-opioid receptors, which possess an antipruritic effect; and numerous cytokines secreted by TH1 lymphocytes, which may significantly contribute to the pathogenic pathways [9]. The gene discussed is OPRK1; the disease is chronic kidney disease.