Alexander disease is a very rare disorder of the nervous system. Normally, nerve fibers are covered by a fatty layer, called myelin. Myelin protects the nerve fibers and helps them transmit impulses. In Alexander disease, myelin is destroyed. This means that the transmission of nerve impulses is disrupted, and nervous system functions are impaired.
Unusual protein deposits in the specialized cells that support the brain and spinal cord are also found in people with Alexander disease.
The symptoms of Alexander disease can vary. They’re largely dependent on the age of onset. Symptoms can include:
- learning disability
- feeding problems
- enlarged head size
- hydrocephalus (fluid in the brain)
- enlarged brain
- delayed development
- failure to thrive
- impaired mobility
- speech problems
- mental regression
- difficulty swallowing
- an inability to cough
- sleep disturbances
The severity of symptoms can also vary greatly. In general, the earlier the onset of the disease, the more severe the symptoms and the more quickly the condition progresses.
Alexander disease is fatal. Many infants with the condition don’t survive past the first year of life. Children who develop the disease between the ages of 4 and 10 tend to decline gradually. They can live for several years following diagnosis, and some may live into middle age.
Alexander disease is caused by a defect in the glial fibrillary acidic protein (GFAP) gene in around 90 percent of cases, according to the Genetic and Rare Diseases Information Center. The GFAP gene is involved in the development of cell structure, but more research is needed to understand GFAP’s specific role within health and disease. It’s unknown what causes Alexander disease in the small number of other cases.
The gene defect doesn’t appear to be hereditary. Instead, it seems to occur at random. Some cases of familial Alexander disease have been reported. However, this is more often in the adult form.
According to the National Institutes of Health, only about 500 cases of Alexander disease have been reported since 1949.
Doctors will often suspect Alexander disease based on the presented symptoms. They’ll then take a blood sample to be sent for genetic testing. In most cases, a blood test is usually all that’s needed for doctors to make a diagnosis.
Currently, there’s no cure for Alexander disease. Only the symptoms can be treated. Since there’s no specific therapy available for the condition, caregivers aim to manage the disease supportively. Particular attention is given to:
- overall care
- occupational and physical therapy
- nutritional needs
- speech therapy
- antibiotics for any infections developed
- antiepileptic drugs to control seizures
Hydrocephalus can be partially relieved by surgery. The surgery involves inserting a shunt to drain away some of the fluid in the brain and relieve the pressure on the brain.
Alexander disease in children
The disorder is most commonly detected in infancy, before the age of 2. It’s characterized by:
- stiffness in the arms and legs
- enlarged brain and head size
- learning disability
- developmental delay
Less frequently, the disease can develop later in childhood. Older children tend to exhibit similar symptoms to adults with the condition.
Alexander disease in adults
When onset occurs in older children and adults, symptoms typically include:
- poor coordination (ataxia)
- swallowing difficulties
- speech problems
Generally, Alexander disease is less severe when it develops in adulthood. Head size and mental capacity can be completely normal at this stage. However, sometimes there’s a slow mental decline.
Alexander disease in older adults (65+)
It’s extremely rare for Alexander disease to develop this late in life. If it does, symptoms are often mistaken for those of multiple sclerosis or a brain tumor. The severity of the disease is often so mild in these cases that Alexander disease is diagnosed after death, when an autopsy reveals the unusual protein deposits in the brain.
The outlook for people with Alexander disease is generally quite poor. Outlook largely depends on what age onset occurs. Infants who develop the disease before the age of 2 normally don’t survive past the age of 6. For older children and adults, the disease usually takes a slower course, and symptoms aren’t as severe. In some adult cases of the disease, there can be no symptoms present at all.
If your child has received a diagnosis of Alexander disease, there are organizations that can provide support. The United Leukodystrophy Foundation and Contact not only offer help and support, but can also connect you with other families who have children with the same condition.