Pelizaeus-Merzbacher disease




Pelizaeus–Merzbacher disease (PMD) is a rare central nervous system disorder in which coordination, motor abilities, and intellectual function are delayed to variable extents.


Symptoms in infants include:

  • Slow growth
  • Nystagmus
  • Poor head control

Symptoms in adults include:

  • Deteriorating speech
  • Tremor
  • Involuntary movements
  • Grimacing
  • Weakness
  • Unsteady gait
  • Muscle contractures
  • Spasticity
  • Mental deterioration
  • Convulsions
  • Skeletal deformation


The diagnosis of PMD is often first suggested after identification by magnetic resonance imaging (MRI) of abnormal white matter (high T2 signal intensity, i.e. T2 lengthening) throughout the brain, which is typically evident by about 1 year of age, but more subtle abnormalities should be evident during infancy. Unless there is a family history consistent with sex-linked inheritance, the condition is often misdiagnosed as cerebral palsy. Once a PLP1 or GJA12 mutation is identified, prenatal diagnosis or preimplantation genetic diagnostic testing is possible.


The prognosis for those with Pelizaeus-Merzbacher disease is poor. The course of the disorder is usually progressive deterioration until death.


There is no cure for PMD, nor is there a standard course of treatment. Treatment, which is symptomatic and supportive, may include medication for seizures and spasticity. Regular evaluations by physical medicine and rehabilitation, orthopedic, developmental and neurologic specialists should be made to ensure optimal therapy and educational resources. The prognosis for those with Pelizaeus–Merzbacher disease is highly variable, with children with the most severe form (so-called connatal) usually not surviving to adolescence, but survival into the sixth or even seventh decades is possible, especially with attentive care. Genetic counseling should be provided to the family of a child with PMD.

In December 2008, StemCells Inc., a biotech company in Palo Alto, received clearance from the U.S. Food and Drug Administration (FDA) to conduct Phase I clinical trials in PMD to assess the safety of transplanting human neural stem cells as a potential treatment for PMD. The trial was initiated in November 2009 at the University of California, San Francisco (UCSF) Children's Hospital.