Adrenoleukodystrophy (ALD) is a progressive, genetic disease that affects the adrenal glands, the spinal cord, and the white matter (myelin) of the nervous system. ALD is considered a rare disease, and affects approximately 1 in 15,000 people worldwide.
What is ALD?
What are the symptoms of ALD? How does it progress?
Change to: ALD symptoms can vary depending on age, gender, and the body tissues affected. The tissues that are most severely affected in ALD are myelin, blood, and the adrenal glands. Not all tissues are affected at the same time.
In the world of genetic disorders, doctors group collections of symptoms into “phenotypes” based on the cells and tissues that are most severely affected by a gene abnormality. Individuals with the ALD gene may have different phenotypes. A person may experience several phenotypes throughout their life. In fact, it is common for individuals to have more than one phenotype at any given time.
The primary phenotypes that can occur in males with the ALD gene:
- Asymptomatic (Newborn Screening)
- Adrenal insufficiency
- Cerebral ALD
- Adrenomyeloneuropathy (AMN)
Women can also develop symptoms.
Babies identified by Newborn Screening have this phenotype. Most individuals with the ALD gene are free of clinical symptoms for at least the first three years of life. ALD does not cause developmental delay. Some individuals have no symptoms for many years, but as the diagram shows, the percentage of asymptomatic men and women decreases with age.
Adrenal insufficiency occurs as a result of permanent injury to the adrenal glands. More than 80% of men with ALD will eventually develop adrenal insufficiency over their lifespan. Adrenal insufficiency is very uncommon in women with ALD. Adrenal insufficiency is sometimes referred to as Addison’s disease, named for Dr. Thomas Addison, who first described it. Symptoms can include weakness/fatigue, nausea, abdominal pain, and low blood pressure. These symptoms can have many different causes and therefore are often not recognized to be due to adrenal insufficiency. Some symptoms such as darkening of the skin are a more obvious sign of adrenal insufficiency. Because of the high rates of adrenal insufficiency in the male population, testing for insufficiency is extremely important, and an endocrinologist should be consulted. Although it is easily treatable with oral medications, adrenal insufficiency can be life-threatening if it is not recognized quickly. Patients and caretakers should educate themselves about the importance of stress-dosing steroids with illnesses and major injuries.
Childhood cerebral adrenoleukodystrophy (cerebral ALD) is a rapid and often fatal disease that mostly affects boys between the ages of 4-10 years. Affected boys’ symptoms may include “spacing out” in school: inattention, deterioration in handwriting skills, and decreased school performance; difficulty in understanding speech (though sound perception is normal); difficulty in reading and understanding written material; clumsiness; visual disturbances and occasionally double-vision; and aggressive or unexplained inappropriate behavior. In some boys, seizures may be the first symptom. Symptom severity varies from patient to patient and is not determined by phenotype. Even identical twins may have different experiences with symptom onset and severity.
Although less common, teenage and adult males may also develop the cerebral variant of ALD. In adults, the first symptoms are often psychiatric and can resemble depression or psychosis. Additional symptoms may include hearing and visual impairment, problems with coordination, and seizures.
The AMN phenotype generally develops in adults. AMN affects the longest nerve fibers of the spinal cord. These fibers conduct signals from the brain to the legs and the bladder and back to the brain. Some people experience some of the following symptoms:
Walking and balance problems
Pain, numbness, or tingling in the legs
Mild to moderate weakness of the arms/hands
Urinary disturbances or incontinence and bowel urgency or incontinence
Sexual dysfunction, or the inability to obtain or maintain an erection