Interestingly, artemin, a glial cell-derived neurotrophic factor (GDNF)-related family, is reported to be important in warm inducing itch because artemin is upregulated in fibroblasts from AD lesions, and an intradermal injection of artemin in mice leads to an increased number and sprouting of peripheral nerves together with thermal hyperalgesia [160, 161]. The gene discussed is GDNF; the disease is Alzheimer disease.