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PLP1 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

PLP1 gene

The PLP1 gene provides instructions for producing proteins essential for the formation and maintenance of myelin, the protective sheath that insulates nerve fibers in the central nervous system.

Normal Function

The PLP1 gene provides instructions for producing proteolipid protein 1 and a modified version (isoform) of that protein called DM20. Proteolipid protein 1 is found primarily in the brain and spinal cord (the central nervous system). DM20 is produced mainly in the nerves that connect the brain and spinal cord to muscles (the peripheral nervous system).

These two proteins are found within the cell membrane of nerve cells called oligodendrocytes, which help coat nerve cells with a protective layer called myelin. Myelin is the fatty sheath that insulates nerve fibers and promotes the rapid transmission of nerve impulses. Proteolipid protein 1 and DM20 make up a large proportion of myelin and help myelin stay anchored to the cells.

Health Conditions Related to Genetic Changes

Pelizaeus-Merzbacher disease

Hundreds of variants (also called mutations) in the PLP1 gene have been found to cause Pelizaeus-Merzbacher disease. This inherited condition involves the central nervous system and primarily affects males. Individuals with this disease experience neurological problems, including abnormal eye movements (nystagmus) and other movement abnormalities. Some affected individuals have difficulty walking, while others are not able to walk.

  • Duplication: An extra copy of the PLP1 gene accounts for 50 to 70 percent of variants causing the disease.
  • Amino Acid Changes: In 10 to 25 percent of cases, variants change single protein building blocks, leading to the production of excess or misfolded proteins. These proteins become trapped within cell structures, causing the swelling and breakdown of nerve fibers.
  • Deletion: In less than 2 percent of cases, a variant that deletes the entire PLP1 gene prevents cells from producing proteolipid protein 1 and DM20.

All of these variants prevent the proteins from reaching the nerve cell membrane, leading to decreased myelin production and the loss of nerve fibers (leukodystrophy).

Spastic paraplegia type 2

Several variants in the PLP1 gene cause spastic paraplegia type 2, a disorder characterized by muscle stiffness (spasticity), weakness that worsens over time, and paralysis of the lower limbs (paraplegia). This condition is part of a group of disorders known as hereditary spastic paraplegias.

  • Pure vs. Complex: The condition can be classified as pure (more common) or complex. The complex type is sometimes called hypomyelination of early myelinating structures (HEMS).
  • Mechanism: These variants typically disrupt the production of proteolipid 1 protein but do not interfere with DM20. This impairs myelin function, resulting in reduced myelin production (hypomyelination).
  • Severity: Because individuals with this condition are able to produce some myelin, their symptoms are generally milder than those of people with Pelizaeus-Merzbacher disease.

Genomic Location

The PLP1 gene is found on the X chromosome.

Frequently Asked Questions

PMD primarily affects males and typically presents in infancy or early childhood. Early signs often include abnormal eye movements (nystagmus), head tremors, and difficulties with motor development such as poor head control, muscle weakness, and problems with coordination. As the disease progresses, individuals may experience increasing difficulty with walking, speech, and other neurological functions.
duplication, or an extra copy, of the PLP1 gene is the most common genetic change causing Pelizaeus-Merzbacher disease, accounting for 50 to 70 percent of cases. Instead of having two normal copies of the gene (one on each X chromosome in females, one in males), affected individuals have extra copies. This excess genetic material leads to the production of too much proteolipid protein 1 and DM20. The overabundance of these proteins interferes with the proper formation and maintenance of myelin, causing it to be unstable or poorly formed, which impairs nerve signal transmission in the brain and spinal cord.
Pelizaeus-Merzbacher disease is an X-linked inherited condition, meaning the PLP1 gene is located on the X chromosome. Males are primarily affected because they have only one X chromosome. Females typically carry the mutation on one X chromosome but have a second, functional X chromosome, so they are usually unaffected or have milder symptoms. An affected male inherits the mutation from his carrier mother. For carrier mothers, there is a 50% chance with each son that he will be affected and a 50% chance with each daughter that she will be a carrier. Genetic counseling is highly recommended for families to understand their specific risks and reproductive options.
Currently, there is no cure for Pelizaeus-Merzbacher disease. Treatment is supportive and focuses on managing symptoms and improving quality of life. This may include physical therapy, occupational therapy, and speech therapy to help with motor skills and communication. Medications may be used to manage symptoms like spasticity or seizures. Regular monitoring by a multidisciplinary team is essential to address the evolving needs of the individual.
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.

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