Adrenoleukodystrophy: A rare genetic (inherited) disorder characterized by the breakdown or loss of the myelin sheath surrounding nerve cells in the brain and progressive dysfunction of the adrenal gland. Adrenoleukodystrophy (ALD) is one of a group of genetic disorders called the leukodystrophies that cause damage to the myelin sheath of the nerve fibers in the brain. The myelin sheath is a fatty covering which acts as an electrical insulator.
There are several forms of ALD:
- The classic childhood form, which is the most severe and affects only boys, may occur between ages 4 and 10. It affects only boys because the gene is on the X chromosome. Features of this form may include visual loss, learning disabilities, seizures, dysarthria (poorly articulated speech), dysphagia (difficulty swallowing), deafness, disturbances of gait and coordination, fatigue, intermittent vomiting, melanoderma (increased skin pigmentation), and progressive dementia. The most common symptoms are usually behavioral changes such as abnormal withdrawal or aggression, poor memory, and poor school performance.
- Women carriers: Another form of ALD is occasionally seen in women who are carriers of the disorder. Symptoms are mild and may include spastic paraparesis of the lower limbs, ataxia, hypertonia (excessive muscle tone), mild peripheral neuropathy, and urinary problems.
- The milder adult-onset form typically begins between ages 21 and 35. Symptoms may include leg stiffness, progressive spastic paraparesis (stiffness, weakness and/or paralysis) of the lower extremities, and ataxia. Although adult-onset ALD progresses more slowly than the classic childhood form, it can also result in deterioration of brain function.
- Neonatal (newborn) ALD affects both male and female babies. Symptoms may include mental retardation, facial abnormalities, seizures, retinal degeneration, hypotonia (low muscle tone), hepatomegaly (enlarged liver), and adrenal dysfunction. This form is usually quickly progressive.