SCN9A and paroxysmal extreme pain disorder: While NaV1.7 is arguably a well-validated pain target in humans based on genetic evidence from loss-of-function and gain-of-function conditions, including congenital insensitivity to pain, erythromelalgia and paroxysmal extreme pain disorder, it remains to be established if pharmacological inhibition of NaV1.7 can achieve global graded analgesia.