Condition: Pelizaeus Merzbacher disease

Pelizaeus-Merzbacher disease (PMD) is a rare X-linked genetic disorder affecting the central nervous system that is associated with abnormalities of the white matter of the brain and spinal cord. Symptoms develop due to lack of the fatty covering (myelin sheath) of nerve cell fibers. Many areas of the central nervous system may be affected, including the deep portions of the cerebrum (subcortical), cerebellum, brain stem and spinal cord. Signs may include the impaired ability to coordinate movement (ataxia), involuntary muscle spasms (spasticity) that result in slow, stiff movements of the legs, delays in reaching developmental milestones, and late onset loss of motor abilities and progressive deterioration of intellectual function. The neurologic signs of Pelizaeus-Merzbacher disease are usually slowly progressive.

Pelizaeus-Merzbacher disease is associated with abnormalities (mutations) in the PLP1 gene. Several forms of the disorder have been identified including classic PMD; connatal PMD; transitional PMD; and PLP1 null syndrome. Forms of complicated spastic paraparesis and pure spastic paraparesis (designated SPG2) are also caused by the PLP1 gene.