Female Carriers of Adrenoleukodystrophy

Female Carriers of Adrenoleukodystrophy

If you are a woman who has a family member diagnosed with adrenoleukodystrophy (ALD), you may be wondering if you are a carrier of the disease. You may find the following information useful as you address that concern.

About ALD

Mutations in a gene called ABCD1 cause ALD. This gene provides instructions for making an important protein that transports very-long-chain fatty acids (VLCFAs) into a compartment in the cell where they are broken down. Mutations in ABCD1 mean the transport protein cannot function properly and VLCFAs build up in tissues, causing the symptoms of the disease.

ABCD1 is located on the X chromosome (one of two chromosomes that determine biological sex). Females have two X chromosomes while males have one X and one Y chromosome. Males who inherit the X chromosome that carries the faulty gene from their mother will have the disease.

What is a female carrier?

Women who have one X chromosome carrying the mutated ABCD1 gene and one X chromosome carrying a healthy copy of the gene are said to be carriers of ALD. Carriers may not always develop symptoms of the disease, but they have a 50% chance of passing the disease to their children.

Am I a female carrier?

Talk to your doctor and a genetic counselor. They can go over your family medical history and help you determine whether you are at risk of being a carrier of ALD.

If you would like to receive a genetic test for ABCD1 mutations, your doctor can help arrange it. After you receive the results of a genetic test, your doctor and a genetic counselor can help you interpret them and determine what next steps, if any, you should take.

What are the risks?

Although female carriers are less likely to develop symptoms of the disease, about 40% of female ALD carriers develop mild neurological symptoms similar to adrenomyeloneuropathy (AMN) in their 30s and 40s. These symptoms can include changes in reflexes and sensation, especially in the extremities. A portion of female carriers may also develop spinal cord disease.

Risks for my children?

If you are an ALD carrier, your children can inherit the disease-causing mutation from you. Both your sons and daughters will have a 50% chance of inheriting the disease-causing mutation. However, if this happens, your sons will have the disease and your daughters will be carriers like you. This is because a son inherits a Y chromosome from their father, whereas a daughter inherits a second X chromosome.

If the father doesn’t have ALD, it means the X chromosome they pass to their daughter carries a healthy copy of the ABCD1 gene, which can compensate for the faulty one coming from the mother.


Last updated: Sept. 15, 2020


Adrenoleukodystrophy News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

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