For example, NaV1.7 is expressed in NaV1.8-positive colonic neurones and yet mice lacking NaV1.7 in NaV1.8-positive neurones although having diminished somatic pain, experience normal visceral pain [28]; articular neurones have smaller acid responses, but greater likelihood of responding to ATP than cutaneous neurones [29], and of all 6 ASIC subunits, ASIC3 mediates acid-excitation of dural, corneal, and cardiac afferents, possibly contributing to the pain of headache, corneal pathologies, and cardiac ischaemia, respectively [30–32]. The gene discussed is SCN9A; the disease is Headache.