Pelizaeus Merzbacher Disease (X-linked spastic paraplegia)
Pelizaeus-Merzbacher disease takes its name from the two German neurologists who first described its main symptoms. The condition is caused by mutations which affect the gene controlling proteolipid protein (PLP). PMD appears to be X-linked, with mostly males being affected. Occasionally, though, females also develop the disease.
Symptoms usually appear in infancy, with the first sign usually being involuntary movements of the eyes, known as nystagmus. Sometimes laboured breathing accompanies this. Later, infants may show hypotonia or spasticity, with increased muscle tone. Intellectual and motor milestones such as sitting and crawling may be delayed. There may be wavering or tremor through the upper body due to impaired control of the head and trunk, and very occasionally the infant may have seizures. Some mutations of the PLP gene may result in a less severe disorder, involving spastic paraparesis, and gait disturbance due to spastic legs.
The prognosis of PMD is variable; Sometimes the mutations are more severe, leading the death of the sufferer at an early age, but other individuals survive into their thirties or fifties. The disorder tends to be progressive until death.
Currently there is no cure for PMD, and no standard course of treatment exists. Most care is symptomatic and supportive, and may include medication for movement disorders and seizures where these occur. There is a consortium of clinicians and researchers working on PMD in the United States, dedicated to research of the causes of the disorder and, hopefully, a cure.
Further information can be obtained from:
Pelizaeus Merzbacher Disease (X-linked spastic paraplegia) [external]