Frequently Asked Questions
- What causes ALD?
- How does ALD affect an individual?
- How do you get ALD?
- Why are boys with ALD typically affected more than girls as children?
- Could other children in the family also have ALD?
- Do women with ALD experience symptoms?
- Who should be tested for ALD?
- What is myelin (white matter) and why is it so important in the nervous systems?
- What is the prevalence of ALD?
- Are there any treatments?
What causes ALD?
When the VLCFAs build up in the central nervous system, they can eventually destroy the myelin sheath—the protective, insulating coating—that surrounds the nerves. If this occurs in the brain, it often leads to neurologic problems, while in the spinal cord, it can lead to difficulty walking. VLCFAs are also toxic to adrenal gland cells. The toxicity leads to those cells malfunctioning, which then causes adrenal insufficiency.
How does ALD affect an individual?
How do you get ALD?
If a mother has ALD, she usually has one X chromosome with a functional ABCD1 copy and one X chromosome with a non-functional ABCD1 copy. Whether or not her child is a boy or girl, she passes one of her two X chromosomes to her child. Therefore, a mother with ALD has a 50% chance that each child, regardless of sex, will inherit the non-functional ABCD1 gene and have ALD themselves.
If a father has ALD, typically the only X chromosome he has contains the defective ABCD1 gene. When males have children, they always pass their only X chromosome to all of their daughters and their only Y chromosome to all of their sons. Therefore, a man with ALD or AMN has a 0% chance that any of his sons will inherit his ALD and a 100% chance that each of his daughters will inherit ALD.
Why are boys with ALD typically affected more than girls as children?
Do women with ALD experience symptoms?
Could other children in the family also have ALD?
Who should be tested for ALD?
How is someone tested for ALD?
Newborn screening is a screening test conducted with dried blood spots taken from a baby just after birth. In many states, ALD is included on the newborn screening panel, and babies are screened for ALD using a modified VLCFA test. If a baby screens positive for ALD, they will have confirmatory diagnostic testing before being officially diagnosed with ALD.
What is myelin (white matter) and why is it so important in the nervous systems?
When myelin is damaged, communication is lost during transmission. This results in the loss of voluntary and involuntary functions in the body.
Currently, there is no known treatment to reverse damaged myelin, although there are options to manage symptoms. Proactive, comprehensive medical care will allow families and caregivers to give the affected individual the best quality of life possible. Furthermore, through ALD Newborn Screening, affected children have the opportunity to benefit from lifesaving treatment, which can halt the disease (see Treatment Section).
What is the prevalence of ALD?
Are there any treatments?
For the most serious phenotype, childhood cerebral ALD, there are potentially lifesaving procedures available. In boys and adolescents with early-stage cerebral ALD, hematopoietic stem cell transplantation (HSCT) can stop the progression of the degradation of the myelin in the brain if the procedure is performed at a very early stage of the disease. After intensive chemotherapy, HSCT relies on bone marrow stem cells from another person who “matches” the patient. The procedure aims to use the donor-derived cells to produce the ABCD1 protein that the recipient is incapable of making.
Gene therapy is another type of stem cell transplant that uses the patient’s own cells as a therapy. In gene therapy for ALD, a patient’s cells are removed from the body, modified to produce a functional ABCD1 protein, and then transplanted back into the body. Gene therapy was recently approved by the FDA for boys with cerebral ALD. Both HSCT and gene therapy are potentially life-saving treatments, but both treatments come with risks that should be carefully evaluated and discussed with a team of medical professionals.
There are currently no specific treatments for the adult spinal cord manifestation of the disease, so treatment is typically aimed at managing symptoms. However, there are clinical trials currently ongoing for adult patients.