Adrenoleukodystrophy (ALD)

What is adrenoleukodystrophy?

Adrenoleukodystrophy (ALD) is a rare genetic condition that causes the buildup of very long chain fatty acids (VLCFAs) in the brain. When VLCFAs accumulate, they destroy the protective myelin sheath around nerve cells, responsible for brain function. Without the myelin sheath, the nerves can no longer relay information to and from the brain.

The defective gene in ALD, commonly referred to as a genetic mutation, can cause several different but related conditions: adrenomyelopathy (AMN), Addison’s disease and — the most common and most devastating form — cerebral ALD. Cerebral ALD strikes boys between ages 4 and 10, leading to permanent disability and death usually within four to eight years.

One in every 21,000 males is born with ALD. Although females who carry the ALD gene mutation do not develop the full ALD condition, approximately half may develop some symptoms.

Meet Brandon and Brian.

What happens when you have two sons with the same rare disease — when there’s a cure one but not the other?


Brothers Brandon and Brian, both of whom have ALD, share a hug

What causes ALD?

ALD is an X-linked recessive condition caused by a mutation in the ABCD1 gene on the X chromosome. Because a female has two X chromosomes, if she inherits the faulty gene, then she still has another X chromosome to offset the mutation. However, because males only have one X chromosome, the gene abnormality causes the disease.

With each pregnancy, female ALD carriers have a 25 percent (1 in 4) chance of having a carrier daughter and a 25 (1 in 4) percent chance of having a son affected with the disease.

What are the symptoms of ALD?

Boys with cerebral adrenoleukodystrophy usually begin showing symptoms between the ages of 4 and 10. The most common symptoms include:

  • behavioral problems
  • withdrawal or aggression
  • poor memory
  • poor school performance
  • difficulty reading and writing and understanding speech

As the condition progresses, other signs and symptoms of cerebral ALD may include:

  • vision problems
  • seizures
  • difficulty swallowing
  • deafness
  • poor coordination
  • inability to speak or respond

Without treatment, ALD progresses rapidly, often leading to a vegetative state or death within a few years.