Periaxin protein is a membrane-associated protein expressed in myelinating Schwann cells. It is required for the stable maintenance and development of a normal myelin sheath in the peripheral nervous system. It is also a member of cytoskeletal complexes in lens fibers where it plays an important role in maturation, packing, and membrane organization of lens fiber cell^1,2. 

The periaxin gene (PRX) encodes two protein isoforms, L-periaxin and S-periaxin generated by alternative mRNA splicing. These proteins contain N-terminal PDZ domains (PSD-95/Discs-large/ZO-1) important for organizing protein–protein interactions.

L-periaxin is a component of the dystroglycan–dystrophin-related protein-2 complex (DRP2) linking the Schwann cell cytoskeleton to the extracellular matrix. Its location changes during myelination; at first the protein is localized to the adaxonal plasma membrane and later, in the abaxonal plasma membrane. S-periaxin is distributed in a uniform manner in the cytoplasm and the nucleus of the Schwann cell^1-3. 

Mutations in the Periaxin gene are known to cause autosomal recessive demyelinating in Type 4F Charcot-Marie-Tooth (CMT4F) and Dejerine-Sottas disease³.

Periaxin knockout mice develop normally myelinated peripheral nervous system at first but develop a late onset demyelinating peripheral neuropathy¹.