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Adrenoleukodystrophy: Symptoms, Statistics & Treatment

Instructor: Jennifer Brest

Jennifer has a Master's Degree in Nursing. Her specialty is pediatrics. She has worked in hospital care, primary care, home care, government, and teaching.

Adrenoleukodystrophy (ALD) is is a potentially devastating genetic disease occurring mostly in boys and men. In this article learn about the different types of ALD, their symptoms, and treatment options.

What is Adrenoleukodystrophy?

Adrenoleukodystrophy, or ALD, is a condition in which the white matter (leuko) of the adrenal glands (adreno) and nervous system is damaged (dystrophy). The effects of this damage range from mild and treatable to devastating and fatal.

The damage is caused by an abnormal gene on the X chromosome. The abnormal gene creates an abnormal protein. This protein's normal responsibility is to carry very long chain fatty acids (VLCFAs) into the part of the cell that breaks them down. The abnormal protein can't do that, so the VLCFAs accumulate. VLCFAs are toxic to cells that create blood cells, hormones, and myelin.

When VLCFAs affect blood cells, they damage the white blood cells, causing inflammation. The inflammation damages the nerve cells.

When VLCFAs damage the cells that produce hormones, the result is deficiencies of hormones that react to stress, regulate blood pressure, and maintain male sexual traits.

Myelin is the white matter of the nervous system. It is the protective coating around a nerve, much like the insulation surrounding an electrical wire. Myelin is responsible for transporting nerve signals quickly and accurately. When myelin is damaged, the nerves can't tell the muscles what to do, and the brain can't think properly.

Normal nerve signal transmission compared to nerve signal transmisson when myelin is damaged
Comparison of nerve function of normal nerve cell with myelin-damaged nerve cell

ALD affects about one in 20,000 people. It affects boys and men more severely. It spans all ethnic groups.

Types and Symptoms

There are six types of ALD, classified by symptoms and by age of onset.

It is important to note that not all people will have all symptoms, and that timelines for age of onset and progression of the disease vary somewhat from study to study.

Typically, anyone with neurological symptoms of the disease will also have adrenal insufficiency. However, people with adrenal insufficiency don't always have neurological symptoms.

Remember that the abnormal gene is on the X chromosome. Males have one X chromosome, so the disease has its maximum effect. Females have two X chromosomes, so they typically have one abnormal gene and one normal gene. So for females, ALD is usually a milder disease with a later onset.

Type Age of Onset Symptoms Progression
Childhood Cerebral ALD 4-8 years ADHD
Difficulty with reading comprehension
Difficulty with understanding speech despite normal hearing
Deterioration in handwriting
Problems with vision
Worsening behavior and emotional disturbance
Clumsiness
Fatigue
Long recovery time from illness or injury
Headache
Vomiting
Seizures
Rapid. Coma within six months to ten years (two years is average). Death ten years after coma.
Adolescent Cerebral ALD 11-21 years Same as the childhood form Slower than the childhood form
Adrenomyeloneropathy (AMN) late 20s Stiffness in legs
Lack of coordination
Generalized muscle weakness
Difficulty walking
Vision loss
Difficulty speaking
Weight loss
Urinary Dysfunction
Impotence
Cognitive Deficits
Depression
Other emotional disturbances
Seizures
Adrenal Insufficiency
Most victims will require a cane or wheelchair within five to 15 years
Adult Cerebral ALD 20s to 50s Same as AMN, except begins with symptoms similar to schizophrenia with dementia Rapid. Coma or death within three to four years after onset of symptoms.
Adrenal Insufficiency 30s to 50s, but adrenal insufficiency as a component of other forms of ALD occurs earlier Fatigue
Muscle weakness
Loss of appetite
Craving salty foods
Weight loss
Abdominal pain
Unexplained vomiting
Diarrhea
Low blood pressure
Low blood sugar
Irritability and depression
Headache
Sweating
Increased skin pigmentation
Usually no neurological symptoms
Effectively treated with steroids (lifelong). May develop AMN later.
Female After age 35 Progressive stiffness, weakness, or paralysis of the legs
Numbness
Pain in joints
Urinary problems
Usually no adrenal insufficiency
About 1/2 of women who carry the genetic mutation will develop symptoms similar to AMN. The symptoms are milder and later in onset.

Treatment

A bone marrow transplant can halt the progression of the disease in children with the cerebral form of the disease. There is a period of six to 18 months after the transplant when the disease continues to progress. Therefore, the procedure is only effective if it done early in the course of the disease: between the time the boy's MRI shows the disease and the time he begins developing neurological symptoms. Even then, because of the continued disease progression, the boy will end up with more neurological damage than he had going in to the procedure. For this reason, bone marrow transplants are not effective later in the course of the disease. In fact, a late bone marrow transplant may even cause the child to rapidly advance into a coma. Bone marrow transplants have not been effective in adults with the disease.

Gene therapy is a form of bone marrow transplant that is in the experimental stage. In this procedure, rather than using bone marrow from a donor, some of the child's own bone marrow is extracted and a normal copy of the gene is inserted into it. This means there is less risk of rejection. This procedure was shown to halt the progression of ALD after 14 to 16 months.

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