Pelizaeus–Merzbacher disease

X-linked recessive (carrier mother)

Pelizaeus–Merzbacher disease (PMD) is a rare, progressive, degenerative central nervous system disorder in which coordination, motor abilities, and intellectual function deteriorate. It is one of a group of genetic disorders known as leukodystrophies, which are characterized by the degeneration of myelin, the fatty covering that insulates nerve fibers in the brain and spinal cord.

Classification[edit | edit source]

Pelizaeus–Merzbacher disease is classified into several types based on the severity and age of onset:

Classic PMD: The most common form, presenting in early infancy.
Connatal PMD: A more severe form, presenting at birth or shortly thereafter.
Transitional PMD: Intermediate severity, with symptoms appearing in late infancy or early childhood.
Adult PMD: A rare form with symptoms appearing in adulthood.

Symptoms[edit | edit source]

The symptoms of PMD vary depending on the type but generally include:

Nystagmus (involuntary eye movement)
Hypotonia (reduced muscle tone)
Ataxia (lack of muscle coordination)
Spasticity (stiff or rigid muscles)
Delayed motor skills development
Cognitive impairment

Genetics[edit | edit source]

Pelizaeus–Merzbacher disease is caused by mutations in the PLP1 gene located on the X chromosome. This gene is responsible for producing proteolipid protein 1, a critical component of myelin. PMD is inherited in an X-linked recessive pattern, meaning that males are more frequently affected, while females are typically carriers.

Diagnosis[edit | edit source]

Diagnosis of PMD involves a combination of clinical evaluation, magnetic resonance imaging (MRI) to detect abnormalities in the brain's white matter, and genetic testing to identify mutations in the PLP1 gene.

Treatment[edit | edit source]

There is currently no cure for Pelizaeus–Merzbacher disease. Treatment focuses on managing symptoms and may include:

Physical therapy to improve motor skills and muscle strength
Occupational therapy to assist with daily activities
Speech therapy to address communication difficulties
Medications to manage spasticity and other symptoms

Prognosis[edit | edit source]

The prognosis for individuals with PMD varies depending on the type and severity of the disease. While some individuals may have a relatively stable course, others may experience significant deterioration in motor and cognitive functions.