Hereditary sensory and autonomic neuropathy type 4 (HSAN4), or congenital insensitivity to pain with anhidrosis (CIPA), is a rare autosomal recessive disorder caused by mutations in the NTRK1 gene, resulting in pain insensitivity, anhidrosis, and temperature dysregulation. Here, NTRK1 is linked to hereditary sensory and autonomic neuropathy type 4.