X-linked Adrenoleukodystrophy (ALD)
Helping you navigate the diagnosis and care plan for your child
What is X-linked ALD?
X-linked Adrenoleukodystrophy is a genetic condition that may be found on Newborn Screening, or can be diagnosed based on a variety of symptoms. Symptoms range in severity and age of onset. There are three main ways that the disease will present:
- 1. Cerebral ALD- marked by progressive neurologic symptoms.
- 2. Adrenomyeloneuropathy (AMN)- marked by difficulties walking or problems with bowel/bladder control.
- 3. “Addison only”- can lead to electrolyte imbalances, low blood sugar and weakness due to impaired adrenal gland function.
Importantly, potentially life-saving therapies are available if the diagnosis of X-linked ALD is made before the onset of symptoms. This is the reason the condition was added to Calinfornia Newborn Screen (NBS) in February, of 2016. For more information about California's Newborn Screening program, click here.
As noted, X-linked ALD is a genetic condition. This means that it is caused by a defect in a gene, or a specific instruction the body uses to function normally. The specific instruction that is impaired in X-linked ALD is a gene called ABCD1. This gene makes an enzyme that helps metabolize, or break down the food we eat.
Specifically, the enzyme made by the ABCD1 gene helps break down very long chain fatty acids, or VLCFAs, which are produced by our body and also obtained from the food we eat. When VLCFAs cannot be broken down, it leads to health complications.
ABCD1, the gene for X-linked ALD, is located on the X chromosome. Chromsomes are the structures that hold our genes within a cell. Females have two X-chromosomes and males have one X chromosome. Thus, females have two copies of the ABCD1 gene (1 on each X chromosome) and males only have 1. Females with a single impaired ABCD1 gene still have a back-up ABCD1 gene that functions normally, and males do not. Therefore, males are typically more severely affected than females.
After your son has been diagnosed with X-linked ALD, regular follow-up is needed. Since we cannot predict the form of ALD that might affect a child (Cerebreal ALD, Adrenomyeloneuropathy, or "Addison only," we recommend close surveillance of adrenal gland function and the brain. The image below provides a surveillance "roadmap."
How will my son's life be different from other boys?
Boys with ALD have normal development. Serious ALD complications (e.g. neurologic disability or death) generally occur only when we are not looking for them. Expert ALD clinicians have designed MRI and lab surveillance schedules to detect ALD complications before they cause permanent disability.
In other words, the goal of ALD surveillance is to keep your son as healthy and active as other boys his age.
What happens if my child’s adrenal labs are abnormal?
What happens if my child’s MRI shows a lesion?
Treatment & Research
Treatment approach depends on the exact presentation of X-linked ALD, and is determined case by case. Some available options are listed below.
- For patients with adrenal gland dysfunction: hormone therapy
- For patients with characteristic changes on brain MRI: hematopoetic stem cell transplant
A number of additional therapies may be available in the future. Patients/families may also consider participation in research studies: http://med.stanford.edu/van-haren-lab/research.html or http://clinicaltrials.gov
Your Stanford Care Team
- Greg Enns, MD
- Chung Lee, MD
- Natalia Gomez-Opsina, MD, PhD
- Keith Van Haren, MD
- Maura Ruzhnikiv, MD
- Sejal Shah, MD