Adrenoleukodystrophy

For the autosomal recessive, neonatal onset disease,
see Neonatal adrenoleukodystrophy.

Adrenoleukodystrophy (ALD) is a rare, inherited genetic disorder that affects the nervous system and adrenal glands. It is characterized by the progressive degeneration of myelin, the protective layer that surrounds nerve fibers in the brain and spinal cord. ALD is caused by mutations in the ABCD1 gene, which is located on the X chromosome, making it an X-linked recessive condition. This means that males are more commonly affected, while females are typically carriers.

There are three main forms of ALD that vary in their age of onset and clinical presentation:

• Childhood cerebral ALD: This is the most severe form of ALD, affecting boys between the ages of 4 and 8. It is characterized by the rapid degeneration of cognitive and motor skills, leading to severe disability or death within a few years.
• Adrenomyeloneuropathy (AMN): This form typically affects adult males and presents with progressive stiffness and weakness in the legs, along with adrenal insufficiency.
• Addison's disease-only ALD: In this form, individuals have adrenal insufficiency without any neurological involvement.

Signs and symptoms

The signs and symptoms of ALD can vary depending on the specific form of the disorder. Some common symptoms include:

• Progressive decline in cognitive and motor skills
• Behavioral changes
• Vision loss
• Hearing loss
• Seizures
• Difficulty swallowing
• Fatigue and muscle weakness
• Adrenal insufficiency, which can cause symptoms such as weight loss, skin discoloration, and low blood sugar

Diagnosis

Diagnosis of ALD is typically based on a combination of clinical symptoms, family history, blood tests, and genetic testing. Blood tests can detect elevated levels of very-long-chain fatty acids (VLCFAs), which are characteristic of ALD. Genetic testing can confirm the presence of a mutation in the ABCD1 gene.

Imaging studies, such as magnetic resonance imaging (MRI) and computed tomography (CT) scans, can help assess the extent of damage to the brain and spinal cord.

Treatment

There is currently no cure for ALD, and treatment primarily focuses on managing symptoms and complications. Treatment options may include:

• Hormone replacement therapy: Individuals with adrenal insufficiency may require corticosteroids to replace the hormones that the adrenal glands are not producing.
• Physical therapy and occupational therapy: These therapies can help maintain muscle strength and function, as well as improve mobility and independence.
• Speech therapy: This can help with swallowing and communication difficulties.
• Medications: Anticonvulsant medications may be prescribed to manage seizures.
• For childhood cerebral ALD, hematopoietic stem cell transplantation (HSCT) has shown some success in slowing or halting the progression of the disease if performed early in the course of the disease.

Prognosis

The prognosis for individuals with ALD varies depending on the specific form of the disorder and the severity of symptoms. Childhood cerebral ALD is often fatal within a few years of onset, while individuals with AMN and Addison's disease-only ALD may have a more variable course.

Epidemiology

ALD has not been shown to have an increased incidence in any specific country or ethnic group. In the United States, the incidence of affected males is estimated at 1:21,000. Overall incidence of hemizygous males and carrier females is estimated at 1:16,800. The reported incidence in France is estimated at 1:22,000.

See also

• Lorenzo's Oil
• Augusto, Michaela, and Lorenzo Odone

External links

Classification	ICD-10: E71.3 ICD-9-CM: 330.0, 277.86 OMIM: 300100 202370 MeSH: D000326 DiseasesDB: 292
External resources	MedlinePlus: 001182 GeneReviews: X-Linked Adrenoleukodystrophy

• adrenoleukodystrophy at NINDS
• Adrenoleukodystrophy at National Center for Biotechnology Information

Adrenoleukodystrophy Resources
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