What is Adrenoleukodystrophy?
Adrenoleukodystrophy (ALD) refers to several different inherited conditions that affect the nervous system and adrenal glands. Other names for it are adrenomyeloneuropathy, childhood cerebral ALD, and Schilder-Addison Complex.
The gene that causes ALD was identified in 1993. It occurs in about 1 in 20,000 people and mainly affects men. Women can carry ALD without having any symptoms. The symptoms, treatments, and prognosis of ALD vary depending on which type is present. ALD is not curable, but the progression can be slowed in some cases.
Types of Adrenoleukodystrophy
There are three types of ALD.
Childhood cerebral ALD mainly affects children who are between 4 and 10 years old. It can progress rapidly if the condition is not found early enough.
Adrenomyelopathy primarily affects male adults. It is milder than childhood cerebral ALD. It also progresses slowly in comparison.
Addison’s disease is the third type of ALD. It is also known adrenal insufficiency. Addison’s disease occurs when your adrenal glands don’t make enough hormones.
Causes and Risk Factors
The adrenoleukodystrophy protein (ALDP) helps your body break down very long chain fatty acids (VLCFA). When this doesn’t happen, the fatty acids build up inside your body instead. This can harm the outer layer of the cells in your spinal cord, brain, adrenal glands, and testes.
People with ALD have mutations in the gene that makes ALDP. Their bodies do not make enough ALDP.
Men are typically affected by ALD at an earlier age than women and usually have more severe symptoms. ALD affects males more than females because it is X-linked. This means that the gene mutation that causes it is on the X chromosome. Men only have one X chromosome, while women have two copies of it. That means that they can have one normal and one mutant copy of the gene.
Women with only one copy of the mutation have much milder symptoms than men. In some cases they don’t have symptoms at all. Their normal copy of the gene makes enough ALDP to help mask their symptoms. Most women with ALD have adrenomyelopathy. Addison’s disease and childhood cerebral ALD are less common.
Symptoms of Adrenoleukodystrophy
Signs of childhood cerebral ALD include:
- muscle spasms
- trouble swallowing
- loss of hearing
- trouble with language comprehension
- impaired vision
- deterioration of fine motor control
- crossed eyes
Signs of adrenomyelopathy include:
- poor control of urination
- weak muscles
- stiffness in the legs
- difficulty thinking and remembering visual perceptions
Signs of adrenal gland failure or Addison’s disease include:
- poor appetite
- weight loss
- decreased muscle mass
- weak muscles
- darker areas of skin color or pigmentation
ALD symptoms can mimic those of other illnesses. Therefore, tests are needed to distinguish it from other neurological conditions. Blood tests can:
- look for abnormally high levels of VLCFAs
- check your adrenal glands
- find the genetic mutation that causes ALD
Your doctor may also look for damage to your brain using magnetic resonance imaging (MRI). Skin samples or a biopsy and fibroblast cell culture can also be used to test for VLCFAs.
Children with suspected ALD may need additional testing, including vision screens.
Treatment of Adrenoleukodystrophy
Treatment methods depend on the type of ALD. Steroids can be used to treat Addison’s disease. There are no specific methods for treating the other types of ALD.
Some people have been helped by:
- switching to a diet that contains low levels of VLCFAs
- taking Lorenzo’s oil to help lower elevated VLCFA levels
- medications to relieve symptoms such as seizures
- physical therapy to loosen muscles and reduce spasms
Doctors continue to look for new ALD treatments. Some are experimenting with the use of bone marrow transplants. These may be able to help children with childhood cerebral ALD when it is diagnosed early.
Prognosis of Adrenoleukodystrophy
Childhood cerebral ALD results in a fatal coma that can last up to 10 years. The long-term coma typically occurs around two years after symptoms begin appearing.
Adrenomyelopathy and Addison’s disease are not as serious as childhood cerebral ALD. They progress at a slower rate. The symptoms can be treated, but there is no cure for ALD.
If you are a woman with a family history of ALD, your doctor will recommend genetic counseling before you have children. DNA probes and tests that check for high VLCFAs can find women who are carriers of ALD 85 percent of the time. An amniocentesis or chorionic villus sampling can be done during pregnancy to diagnose this condition.