What is X-Linked Adrenoleukodystrophy?
X-linked adrenoleukodystrophy (X-ALD) is a genetic condition that primarily affects the nervous system and adrenal glands. X-ALD is more common and more severe in males because of the way it is inherited. Neurologic problems result from deterioration (demyelination) of the insulating covering (myelin) of the nerves in the brain and spinal cord. This causes a decline in intellectual and motor function and ultimately reduces lifespan. X-ALD is also associated with adrenal insufficiency which results in the decreased production of certain hormones causing abnormalities in blood pressure, heart rate and ability to have children.
There are three major forms of X-ALD that occur in males:
Childhood cerebral form
The childhood form is the most severe. Typcially by age 4 years, children will start to experience learning and/or behavior problems that progress over time to impaired understanding, speech, vision, hearing and motor function. The rate of symptom progression is variable, but can result in significant disability within a few years after symptoms start.
Adrenomyeloneuropathy type (AMN)
This type of X-ALD most often presents in early adulthood. Initial symptoms may include: difficulty walking, speech difficulties, loss of muscle movement coordination, impaired sexual function and behavior changes. An absence of hormones (adrenal insufficiency) may also occur and lead to weakness, weight loss, skin changes, vomiting, and coma.
Addison disease only
This is the mildest form of X-ALD. Individuals with this form, often present with symptoms associated with adrenal insufficiency only sometime between childhood and adulthood. During adulhood, symptoms of the AMN type may start to appear. Adrenal function typically remains normal in female carriers.
Different forms of X-ALD can be observed within the same family.
Approximately 20% of female carriers develop symptoms most closely resembling the AMN type. However, the onset of symptoms in female carriers typically present later on in adulthood.
How common is X-Linked Adrenoleukodystrophy?
Collectively, all forms of X-ALD are estimated to occur in approximately 1 in 20,000 to 1 in 50,000 males. X-ALD occurs at a similar frequency across all ethnicities.
How is X-Linked Adrenoleukodystrophy treated?
Currently, there is no cure for X-ALD. However, treatments are available to address many of the symptoms. Corticosteriod replacement therapy is used to treat symptoms caused by adrenal insufficiency, but does not relieve neurologic symptoms. A multidisciplinary team of healthcare professionals, including: neurologists, physical therapists, urologists, ophthalmologists, audiologists, endocrinologists and other healthcare specialists will need to be involved in the treatment and ongoing management of individuals with X-ALD.
What is the prognosis for a person with X-Linked Adrenoleukodystrophy?
The life expectancy of individuals with this type depends on the severity of the signs and symptoms and how quickly the disorder progresses. Individuals with the cerebral form of X-linked adrenoleukodystrophy usually survive only a few years after symptoms begin but may survive longer with intensive medical support. The prognosis for individuals with the AMN type and Addison disease only type vary; in some cases, neurologic damage may lead to early death.