X-linked adrenoleukodystrophy (ALD)
X-linked adrenoleukodystrophy (ALD) is a type of genetic (hereditary) condition (leukodystrophy) that causes damage to the membrane surrounding nerve cells in your brain (myelin sheath). X-linked ALD is caused by a genetic defect on the X chromosome. The condition may occur as childhood-onset ALD or as an adult-onset form of the condition (adrenomyeloneuropathy). It occurs in about 1 in every 20,000 males. Females carry the disease.
- Childhood-onset ALD is a form of X-linked ALD that usually occurs between 4 and 10 years of age. 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.
- The adult-onset form (adrenomyeloneuropathy) is a less severe and slowly progressive form of ALD presenting with stiff gait, bladder and bowel dysfunction.
- Hormone-producing glands (adrenal glands) often fail to produce enough steroids (adrenal insufficiency) in people who have ALD. In Addison's disease, a type of X-linked ALD, people have severe adrenal insufficiency. Neurological symptoms may or may not develop in people who have Addison's disease. Most men with neurological symptoms do develop adrenal insufficiency and require monitoring by an endocrinologist.
- Women who carry the condition may develop a mild form of adrenomyeloneuropathy.