Adrenomyeloneuropathy (AMN)

See also: Adrenoleukodystrophy

Inheritance:

X-linked Inheritance

Age range at onset:

Adulthood

Specialists you may see:

Symptoms

Symptoms of Adrenomyeloneuropathy (AMN) can include stiffness, weakness and pain in the legs. This starts gradually and can progress over time. The medical term for this is ‘progressive spastic paraparesis’. Damage to the nerves supplying the legs means unsteadiness and falls are common. The nerves to the bladder, bowel and sexual organs can also be affected in AMN. Mobility can gradually deteriorate to the point where the sufferer eventually loses the ability to walk and becomes wheelchair bound. But this does not necessarily happen to all sufferers. AMN affects men more severely than women. Women with the gene are sometimes called ‘carriers’, because they can pass the gene to their children but were thought to be unaffected themselves. However, we now know that the gene does cause effects in many women. It is thought that about 80% of women with the gene will develop some symptoms of AMN during their lifetime. Symptoms usually start around the ages of 40 to 50, but can begin earlier or later.

As with ALD, in most males with AMN the adrenal glands are also affected. The adrenal glands make steroid hormones. Poor functioning of these glands is known as adrenal insufficiency, or Addison’s Disease. About 20% of men with AMN eventually develop some damage to nerves in the brain, which may result in dementia-like symptoms. Some men affected in this way go on to experience severe physical and mental deterioration, similar to that seen in boys with cerebral ALD.

Cause

AMN is caused by mutations in the ABCD1 gene. This gene is also affected in ALD, a serious degenerative disease that mainly affects young boys. In AMN, the damage happens in the nerves that control the muscles. It is impossible to predict how the gene will affect any one person, but males are more severely affected than females due to the fact that the condition has X-linked Inheritance.

News, research and treatment

There are currently no drugs that can repair nerves or stop them from dying back, although research into treatments continues. However, drugs can help alleviate some of the symptoms of AMN, such as stiffness. These drugs seem to work for some people, but not for others. Discuss with your consultant the best treatments to help relieve your symptoms.

Progression of AMN to adult forms of cerebral ALD is potentially treatable with a stem cell transplant if it is detected early, although use of this treatment in adults is still experimental. If you would like to know more about this, talk to your consultant for the most up-to-date information. Transplants in adults who are showing signs of cerebral ALD are not common, but practices are changing. It is recommended that all cerebrally asymptomatic adults access yearly MRI scans if they want them.

New Born Screening for ALD would allow more males with ALD to receive treatment before the condition progresses. This has been introduced in parts of the USA, and Alex TLC are actively involved in efforts to introduce it in the UK.

Link between Addison’s Disease and Adrenoleukodystrophy

Project Bostock

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