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Pelizaeus-Merzbacher disease

Pelizaeus-Merzbacher disease

Reviewed March 2008

What is Pelizaeus-Merzbacher disease?

Pelizaeus-Merzbacher disease is an inherited condition involving the brain and spinal cord (central nervous system). This disease is one of a group of genetic disorders called leukodystrophies. Leukodystrophies are characterized by degeneration of myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. Pelizaeus-Merzbacher disease is caused by an inability to form myelin (dysmyelination). As a result, individuals with this condition have impaired intellectual functions, such as language and memory, and delayed motor skills, such as coordination and walking. Typically, motor skills are more severely affected than intellectual function; motor skills development tends to occur more slowly and usually stops in a person's teens, followed by gradual deterioration.

Pelizaeus-Merzbacher disease is divided into classic and connatal types. Although these two types differ in severity, their features can overlap.

Classic Pelizaeus-Merzbacher disease is the more common type. Within the first year of life, those affected with classic Pelizaeus-Merzbacher disease typically experience weak muscle tone (hypotonia), involuntary movements of the eyes (nystagmus), and delayed development of motor skills such as crawling or walking. As the child gets older, nystagmus usually stops but other movement disorders develop, including muscle stiffness (spasticity), problems with movement and balance (ataxia), and involuntary jerking (choreiform movements).

Connatal Pelizaeus-Merzbacher disease is the more severe of the two types. Symptoms can begin in infancy and include problems feeding, a whistling sound when breathing, progressive spasticity leading to joint deformities (contractures) that restrict movement, speech difficulties (dysarthria), ataxia, and seizures. Those affected with connatal Pelizaeus-Merzbacher disease show little development of motor skills and intellectual function.

How common is Pelizaeus-Merzbacher disease?


What genes are related to Pelizaeus-Merzbacher disease?

Mutations in the PLP1 gene cause Pelizaeus-Merzbacher disease. The PLP1 gene provides instructions for producing proteolipid protein 1 and a modified version (isoform) of proteolipid protein 1, called DM20. Proteolipid protein 1 and DM20 are primarily located in the central nervous system and are the main proteins found in myelin, the fatty covering that insulates nerve fibers. A lack of proteolipid protein 1 and DM20 can cause dysmyelination, which can impair nervous system function, resulting in the signs and symptoms of Pelizaeus-Merzbacher disease.

It is estimated that 5 percent to 20 percent of people with Pelizaeus-Merzbacher disease do not have identified mutations in the PLP1 gene. In these cases, the cause of the condition is unknown.

Read more about the PLP1 gene.

How do people inherit Pelizaeus-Merzbacher disease?



Where can I find information about diagnosis or management of Pelizaeus-Merzbacher disease?

These resources address the diagnosis or management of Pelizaeus-Merzbacher disease and may include treatment providers.

You might also find information on the diagnosis or management of Pelizaeus-Merzbacher disease in Educational resources and Patient support.



Where can I find additional information about Pelizaeus-Merzbacher disease?

You may find the following resources about Pelizaeus-Merzbacher disease helpful. These materials are written for the general public.


What other names do people use for Pelizaeus-Merzbacher disease?

  • Cockayne-Pelizaeus-Merzbacher Disease
  • PMD
  • sclerosis; brain, Pelizaeus-Merzbacher


What if I still have specific questions about Pelizaeus-Merzbacher disease?

Where can I find general information about genetic conditions?

What glossary definitions help with understanding Pelizaeus-Merzbacher disease?

ataxia ; carrier ; cell ; central nervous system ; chromosome ; dementia ; dysarthria ; gene ; hypotonia ; inheritance ; inherited ; involuntary ; joint ; motor ; muscle tone ; mutation ; nervous system ; nystagmus ; prevalence ; protein ; recessive ; sclerosis ; sex chromosomes ; spasticity ; X-linked recessive


See also Understanding Medical Terminology.

References (6 links)



Reviewed: March 2008
Published: December 22, 2014