Adrenoleukodystrophy (uh-dree-noh-loo-koh-DIS-truh-fee) is a type of hereditary (genetic) condition that damages the membrane (myelin sheath) that insulates nerve cells in your brain.

In adrenoleukodystrophy (ALD), your body can't break down very long-chain fatty acids (VLCFAs), causing saturated VLCFAs to build up in your brain, nervous system and adrenal gland.

The most common type of ALD is X-linked ALD, which is caused by a genetic defect on the X chromosome. X-linked ALD affects males more severely than females, who carry the disease.

Forms of X-linked ALD include:

  • Childhood-onset ALD. This form of X-linked ALD usually occurs between ages 4 and 10. The white matter of the brain is progressively damaged (leukodystrophy), and symptoms worsen over time. If not diagnosed early, childhood-onset ALD may lead to death within five to 10 years.
  • Addison's disease. Hormone-producing glands (adrenal glands) often fail to produce enough steroids (adrenal insufficiency) in people who have ALD, causing a form of X-linked ALD known as Addison's disease.
  • Adrenomyeloneuropathy. This adult-onset form of X-linked ALD is a less severe and slowly progressive form that causes symptoms such as a stiff gait and bladder and bowel dysfunction. Women who are carriers for ALD may develop a mild form of adrenomyeloneuropathy.