Substance P, IL-2, calcitonin gene-related peptide (CGRP), OPRM, and OPRK are involved in psoriasis-related itch, while thymic stromal lymphopoietin (TSLP), CGRP, IL-4, IL-13, and IL-31 are associated with AD pruritus. The gene discussed is IL13; the disease is Alzheimer disease.