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PMP22 gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

PMP22 gene

The PMP22 gene is critical for the development and maintenance of myelin, the protective substance that insulates nerve fibers and ensures efficient nerve signaling.

Normal Function

The PMP22 gene provides instructions for making the peripheral myelin protein 22 (PMP22). This protein is found in peripheral nerves, which connect the brain and spinal cord to muscles and sensory cells. PMP22 is a component of myelin, a fatty substance produced by Schwann cells that insulates nerve fibers.

The protein plays a crucial role in the development and maintenance of myelin sheaths. It is particularly important in helping nerves restore their structure after compression, which prevents body parts from repeatedly going numb. Before becoming part of myelin, PMP22 proteins must be properly processed and folded within the cell.

Health Conditions Related to Genetic Changes

Charcot-Marie-Tooth disease

Pathogenic variants in the PMP22 gene cause Charcot-Marie-Tooth disease, a neurological disorder resulting in muscle weakness and sensory problems in the hands and feet. Specific types include:

  • Type 1A (CMT1A): Caused by an extra copy (duplication) of the PMP22 gene, leading to an overproduction of PMP22 protein. This disrupts Schwann cell function, impairing the formation (dysmyelination) and maintenance (demyelination) of myelin.
  • Type 1E (CMT1E): Caused by variants that change a single amino acid, preventing the protein from folding or functioning correctly. This can lead to protein accumulation and nerve damage; some individuals also experience hearing loss.
  • Type 3 (CMT3/Dejerine-Sottas syndrome): A severe form typically beginning in infancy or early childhood, characterized by muscle weakness, sensory loss, and delayed motor skill development.

Hereditary neuropathy with liability to pressure palsies

This disorder is most commonly caused by the loss (deletion) of one copy of the PMP22 gene. This reduces PMP22 protein production by approximately half, affecting myelin structure and making nerves more susceptible to injury from pressure or minor trauma. It is characterized by recurrent episodes of numbness, tingling, or loss of muscle function.

Yuan-Harel-Lupski syndrome

Duplication of a small piece of chromosome 17 containing the PMP22 gene and the nearby RAI1 gene causes Yuan-Harel-Lupski (YUHAL) syndrome. Neurological symptoms like muscle weakness and sensory loss are attributed to the PMP22 duplication, while developmental delays and behavioral problems are likely linked to the extra copy of RAI1.

Genomic Location

The PMP22 gene is found on chromosome 17.

Frequently Asked Questions

While the disease is progressive, many patients maintain a reasonable quality of life with appropriate management. Early diagnosis, ongoing physiotherapy, occupational therapy, and, when needed, assistive devices can help preserve mobility and reduce complications.===
Genetic testing is key: CMT1A is caused by a duplication of the PMP22 gene, whereas CMT1E involves point mutations that alter a single amino acid. Electrophysiological studies (nerve conduction velocity) can also help, as CMT1E often shows more severe slowing and conduction block.
Symptoms such as progressive muscle weakness in the feet and hands, loss of sensation, foot drop, and a high arch (pes cavus) that develop in late childhood or early adulthood are classic signs of CMT1A. A family history of similar symptoms also raises suspicion.
Regular use of ergonomic devices, avoiding prolonged pressure on nerves (e.g., from tight shoes or prolonged sitting), and early intervention with physical therapy can help. In some cases, surgical decompression may be necessary for persistent or severe compression neuropathies.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.