The nerve growth factor (NGF)-NTRK1 axis is indispensable for neuronal development and nociceptive signaling [74,75], with its dysregulation implicated in pathologies spanning congenital insensitivity to pain (CIPA) due to loss-of-function mutations to chronic pain hypersensitivity from gain-of-function signaling [75,76]. The gene discussed is NGF; the disease is hereditary sensory and autonomic neuropathy type 4.