SCN9A encodes a voltage-gated sodium channel, and pathogenic variants of the gene result in CIP (HSAN type IID variant).1, 2, 3, 4, 5 Notably, there are multiple genetic abnormalities that lead to various different HSAN subtypes; however, in comparison to other genes, variations in SCN9A are more common.3 The gene discussed is SCN9A; the disease is hereditary sensory and autonomic neuropathy.