Adrenoleukodystrophy (ALD) is a rare, genetic disorder characterized by the breakdown or loss of the myelin sheath surrounding nerve cells in the brain and progressive dysfunction of the adrenal gland.
ALD is one of a group of genetic disorders called the leukodystrophies that cause damage to the myelin sheath -- the fatty covering -- on nerve fibers in the brain.
There are several forms of ALD. Onset of the classic childhood form, which is the most severe and affects only boys, may occur between ages 4-10. Features of this form may include visual loss, learning disabilities, seizures, dysphagia, deafness, disturbances of gait and coordination, fatigue, intermittent vomiting and progressive dementia. The most common symptoms are usually behavioral changes such as abnormal withdrawal or aggression, poor memory and poor school performance.
In the milder adult-onset form, which typically begins between ages 21-35, symptoms may include leg stiffness, progressive spastic paraparesis 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.
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, mild peripheral neuropathy and urinary problems.
Neonatal ALD affects both male and female newborns. Neonatal adrenoleukodystrophy (NALD) is a disorder that is totally distinct from X-linked adrenoleukodystrophy. NALD was assigned that name when its nature was not yet understood, and this nomenclature has led to unfortunate confusion. NALD is now classified as a disorder of peroxisome biogenesis; it is related to the Zellweger syndrome. NALD and X-linked adrenoleukodystrophy never occur in the same family. Symptoms may include intellectual disabilities, facial abnormalities, seizures, retinal degeneration, hypotonia, heptomegaly and adrenal dysfunction. This form is usually quickly progressive.