What is AMN or Adrenomyeloneuropathy?
AMN is a genetic neuro-degenerative disease. It is the adult onset of adrenoleukodystrophy (ALD). This disorder can be broken down into two general clinical forms: AMN with cerebral involvement (the spinal cord and brain are both affected), and AMN without cerebral involvement (only the spinal cord is affected). Whether or not the brain is involved in AMN can be assessed by an MRI.
What Are the Symptoms?
Symptoms can include:
- Difficulty in walking/change in walking pattern
- Gradual, progressive weakness and stiffness of the legs
- Loss of the ability to coordinate muscle movement
- Excessive muscle tone
- Visual defects
- Difficulty in articulating words
- Adrenal insufficiency
- Sexual dysfunction/impotence
- Behavioral changes
- Bladder dysfunction
- Mild peripheral neuropathy
- Weight loss
How Do You Get AMN?
This disorder is caused by mutations in the ABCD1 gene, which gives the body instructions to make the adrenoleukodystrophy protein (ALDP) which helps transport certain types of fats called very long-chain fatty acids into the peroxisomes. Peroxisomes are structures in cells that contain enzymes used to help break down fats and other substances. These mutations cause low levels of functional ALDP, which then causes high levels of very long-chain fatty acids to build up in the body. High levels of these fats in the nervous system, adrenal glands, and testes disrupt their normal function, resulting in the features of this disorder.
How Is AMN Diagnosed?
Diagnosis is confirmed through a blood test that measures the levels of very long-chain fatty acids and/or genetic testing for a mutation in the ABCD1. Additionally, an MRI of the brain may be done to determine if the individual has cerebral involvement or not.
Is There a Treatment?
While there is no cure, many patients take advantage of clinical and dietary treatments which can help alleviate symptoms of the disease. For example, steroid replacement therapy may be prescribed in people with adrenal insufficiency. Physical therapy may also be recommended to help build and maintain muscle strength.
NIH U.S. National Library of Medicine – Genetics Home Reference
NIH U.S, National Library of Medicine – MedlinePlus
National Organization for Rare Disorders (NORD)
United Leukodystrophy Foundation
Genetic and Rare Diseases Information Center