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Adrenoleukodystrophy

What is adrenoleukodystrophy?

Adrenoleukodystrophy (ALD) refers to several different inherited conditions that affect the nervous system and adrenal glands. The three major categories of ALD are childhood cerebral ALD, adrenomyelopathy, and Addison’s disease.

The gene that causes ALD was identified in 1993. According to the Oncofertility Consortium, ALD occurs in about 1 in 20,000 to 50,000 people and mainly affects men. Women with the gene tend to be asymptomatic or mildly symptomatic, meaning there are no symptoms or very few symptoms. The symptoms, treatments, and prognosis of ALD vary depending on which type is present. ALD is not curable, but doctors can sometimes slow its progression.

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Types

Types of adrenoleukodystrophy

There are three types of ALD:

  • Childhood cerebral ALD mainly affects children between 3 and 10 years old. It progresses very rapidly and causes severe disability and even death.
  • Adrenomyelopathy primarily affects adult men. It’s milder than childhood cerebral ALD. It also progresses slowly by comparison.
  • Addison’s disease is also known as adrenal insufficiency. Addison’s disease occurs when your adrenal glands don’t make enough hormones.

Causes

Causes and risk factors

The adrenoleukodystrophy protein (ALDP) helps your body break down very long chain fatty acids (VLCFAs). If the protein doesn’t do its job, the fatty acids build up inside your body. This can harm the outer layer of cells in your:

  • spinal cord
  • brain
  • adrenal glands
  • testes

People with ALD have mutations in the gene that makes ALDP. Their bodies don’t 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 inherited in an X-linked pattern. This means that the responsible gene mutation is on the X chromosome. Men only have one X chromosome, while women have two. Because women have two X chromosomes, they can have one normal gene and one copy with the gene mutation.

Women who have only one copy of the mutation have much milder symptoms than men. In some cases, women who carry the gene 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.

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Symptoms

Symptoms of adrenoleukodystrophy

Symptoms of childhood cerebral ALD include:

  • muscle spasms
  • seizures
  • trouble swallowing
  • loss of hearing
  • trouble with language comprehension
  • impaired vision
  • hyperactivity
  • paralysis
  • coma
  • 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 insufficiency or Addison’s disease include:

  • poor appetite
  • weight loss
  • decreased muscle mass
  • vomiting
  • weak muscles
  • coma
  • darker areas of skin color or pigmentation

Diagnosis

Diagnosing adrenoleukodystrophy

ALD symptoms can mimic those of other illnesses. Tests are needed to distinguish ALD from other neurological conditions. Your doctor may order a blood test to:

  • 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 an MRI scan. 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.

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Treatment

Treatment of adrenoleukodystrophy

Treatment methods depend on the type of ALD you have. 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
  • taking medications to relieve symptoms such as seizures
  • doing physical therapy to loosen muscles and reduce spasms

Doctors continue to look for new ALD treatments. Some doctors are experimenting with bone marrow transplants. If children with childhood cerebral ALD are diagnosed early, these experimental procedures may be able to help.

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Outlook

Outlook of adrenoleukodystrophy

Childhood cerebral ALD can lead to severe disability, coma, and death. Coma typically occurs around two years after symptoms begin appearing and can last for up to 10 years, until death.

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.

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Prevention

Preventing adrenoleukodystrophy

Because ALD is an inherited condition, there’s no way to prevent it. If you’re a woman with a family history of ALD, your doctor will recommend genetic counseling before you have children. An amniocentesis or chorionic villus sampling can be done during pregnancy to determine if your unborn child is affected.

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