Gene : ABCD1

What is Adrenoleukodystrophy?

Adrenoleukodystrophy (ALD) is an inherited disorder characterized by damage to the part of the nervous system that is responsible for protecting nerves in the brain and spinal cord, and the adrenal glands, two small glands located on the top of each kidney that are important hormone producers for the body. Of the three main types seen, the most severe form typically begins between the ages of four and eight years old. Children affected with ALD will have learning problems that worsen over time. These include difficulty reading, writing, understanding speech and comprehension of written material. They also exhibit behavioral issues, which along with the learning problems, are often diagnosed as attention deficit disorder. Vison, hearing and coordination are also impaired. Deterioration of normal function is rapid with complete disability in six months to two years following the first sign of symptoms. Another form of ALD, called adrenomyeloneuropathy, usually appears in early adulthood or middle age. Symptoms are less severe and progression is less rapid. Individuals with this form will experience stiffness in their legs and bladder and bowel dysfunction. Individuals affected with the third form of ALD usually only have issues with their adrenal glands and insufficient hormone production. Some neurologic symptoms may appear later on in life. Life expectancy for ALD is variable, although death usually occurs soon after symptoms worsen with childhood onset. There is no cure for ALD; however aggressive medical care and surveillance may help to improve some symptoms and overall condition of life. ALD is caused by pathogenic variants in the ABCD1 gene.

How is adrenoleukodystrophy inherited?

Adrenoleukodystrophy is inherited in an X-linked recessive manner. This type of inheritance requires the presence of one copy of a pathogenic variant in the gene located on the X-chromosome for males to be affected. When the pathogenic variant is inherited from the unaffected carrier mother, the male child will have the genetic disease. There is a 50% chance that a baby will inherited the pathogenic variant from the mother; females who inherited the pathogenic variant will be carriers, males who inherited the pathogenic variant will be affected.

What does it mean to be a carrier?

There are generally no signs or symptoms associated with being a carrier for ALD. However, the risk to have a child affected with ALD is increased for female carriers.

How common is adrenoleukodystrophy?

ALD is estimated to occur in 1 in 20,000 to 1 in 50,000 male newborns worldwide.

Family References and Resources
Clinician References
What is Analyzed?
  • Full gene sequencing
Affected Systems





Carrier Rates
Detection Rate
Carrier Frequency
General Population 93% 1 in 10500

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