What is Alexander Disease?

Alexander Disease is an extremely rare neurological disorder. The condition is a leukodystrophy, characterized by a lack of normal amounts of myelin. Myelin, the so-called "white matter" of the brain, is very complex and plays an essential role in the body. Myelin is a phospholipid layer that acts as an electrical insulator allowing efficient transmission of nerve impulses. When myelin is destroyed, the transmission of nerve impulses becomes messed up. As Alexander Disease progresses, the function of the nervous system is impaired. Alexander Disease also causes the formation of Rosenthal fibers, a type of fibrous protein deposit. The fibers form in astroglial cells, specialized cells which are responsible for the support and nourishment of nerve cells in the central nervous system.

Who gets Alexander Disease?

The exact prevalence of Alexander Disease is not known. There have been less than five-hundred reported cases of the disease in the last fifty years. The disease affects males more than females. Although in the vast majority of cases the disease presents itself in the first months and years of life, there are cases where the disease does not appear until later in life. Alexander Disease is hereditary, inherited in an autosomal dominant manner. However, almost all cases of the disease are a result of a new mutation and there is no family history of the disease.

What causes Alexander Disease?

Alexander Disease is caused by a mutation in glial fibrillary acidic protein (GFAP) gene on chromosome 17. The GFAP gene is responsible for providing the body with instructions for making glial fibrillary acidic protein which helps to form intermediate filaments, important components of astroglial cells. Any mutations in the GFAP gene alter the structure of glial fibrillary acidic protein thereby affecting astroglial cells. This eventually leads to the characteristic Rosenthal fibers, however, the exact link between the disruption in astroglial cells and the disruption of myelin is not understood.

What are the symptoms of Alexander Disease?

Symptoms of Alexander Disease vary depending at the time of onset. Onset can occur in infancy, childhood or adolescence, or adulthood. Signs and symptoms of the infantile form of Alexander Disease include failure to thrive; delays in physical, mental, and behavioral development; seizures; enlarged brain and head; stiffness in the arms and/or legs; and progressive neurological deterioration. When the onset of the disease occurs later in life, symptoms include mental retardation, dementia, poor coordination, swallowing difficulties and speech abnormalities.How is Alexander Disease diagnosed?

Diagnosis of Alexander Disease can be particularly difficult. The only true test for Alexander Disease is genetic testing. Imaging tests, usually MRIs, combined with physical examinations and a medical history also aid in the diagnosis.

How is Alexander Disease treated?

There is no cure for Alexander Disease. There is also no standard course of treatment. Treatment is highly individualized and aimed at treating the symptoms.

What is the prognosis of those with Alexander Disease?

Prognosis of Alexander Disease is poor. In general, the earlier the onset is, the more progressive the disease is. In infantile onset, patients usually do not make it to their tenth birthdays. Juvenile and adult onset patients, on the other hand, tend to live longer.Sources

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