Periaxin is a protein that in humans is encoded by the PRX gene. This gene encodes a protein involved in peripheral nerve myelin upkeep. The encoded protein contains 2 PDZ domains which were named after PSD95 (post synaptic density protein), DlgA (Drosophila disc large tumor suppressor), and ZO1 (a mammalian tight junction protein). Two alternatively spliced transcript variants have been described for this gene which encode different protein isoforms and which are targeted differently in the Schwann cell. Mutations in this gene cause Charcot-Marie-Tooth neuoropathy, type 4F and Dejerine-Sottas neuropathy.