The human body consists of cells. These cells contain a nucleus with the DNA. The DNA contains all the information that an organism uses to function. The DNA is contained within chromosomes. Humans have 46 chromosomes.Each chromosome contains the DNA for many genes.

A subset of patients with small fibre neuropathy has a genetic change in the SCN9A-, SCN10A- or SCN11A-gene. These genes contain the information for certain sodium channels, responsible for the generation of signals in small nerve fibres.