Adrenoleukodystrophy (ALD) is a genetic condition that affects the protective sheath surrounding nerve cells in the brain, known as myelin. This sheath is crucial for the efficient transmission of nerve signals. In individuals with ALD, this vital insulation is damaged, leading to a range of neurological problems.
In ALD, the body struggles to break down very long-chain fatty acids (VLCFAs). This metabolic malfunction causes a buildup of saturated VLCFAs in various parts of the body, most notably in the brain, nervous system, and adrenal glands. This accumulation is toxic and disrupts normal cellular function, particularly affecting the myelin sheath.
The most prevalent form of ALD is X-linked ALD. This genetic disorder is caused by a defect on the X chromosome. Males are more severely affected by X-linked ALD because they have only one X chromosome. Females, who have two X chromosomes, can be carriers of the disease and may experience milder symptoms or different forms of the condition.
X-linked ALD manifests in several forms, each with varying onset and severity:
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Childhood-onset ALD: Typically emerging between the ages of 4 and 10, this is the most aggressive form. It leads to progressive damage of the brain’s white matter, a process known as leukodystrophy. Symptoms worsen rapidly, and without early and accurate ALD diagnosis, this form can be fatal within 5 to 10 years. Early detection is critical to managing this severe form of the disease.
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Addison’s disease: ALD can also manifest as Addison’s disease, characterized by adrenal insufficiency. The adrenal glands, responsible for producing essential hormones like steroids, fail to produce sufficient amounts. This hormonal imbalance is another facet of X-linked ALD.
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Adrenomyeloneuropathy (AMN): This is an adult-onset form of X-linked ALD. It is less severe than childhood-onset ALD and progresses more slowly. Symptoms include a stiff gait and bladder and bowel dysfunction. It’s important to note that women who are carriers of ALD may also develop a milder form of adrenomyeloneuropathy later in life.
Close-up of nerve cell with myelin sheath
Understanding the different forms of ALD is crucial for timely and accurate Adrenoleukodystrophy diagnosis. Recognizing the symptoms and risk factors allows for prompt medical intervention and management strategies tailored to the specific type of ALD. While there is no cure for ALD, early diagnosis and treatment can significantly impact the course of the disease, especially in childhood-onset ALD. Diagnostic procedures often involve blood tests to measure VLCFA levels, genetic testing to confirm the X-linked defect, and MRI scans to assess brain involvement. Therefore, if symptoms suggestive of ALD arise, seeking a comprehensive ALD diagnosis is the first step towards appropriate care and management.
Adrenoleukodystrophy care at Mayo Clinic
Feb. 07, 2020
