Very little is currently known about the sensory characteristics and central processing of pain in patients with heritable channelopathies. The investigators will carefully study the phenotype of such patients in terms of pain symptomatology, sensory processing as revealed by quantitative sensory testing and correlate this with genotype. In select patients the investigators will perform skin biopsy to determine whether there is any evidence of damage to small fibres and would also like to generate fibroblast and neural crest stem cell cultures for future studies of the molecular basis for channel dysfunction.