Adrenoleukodystrophy (ALD) is a rare progressive neurological disorder. Children with the disease lack an ability to process very-long-chain fatty acids (VLCFAs) due to mutations in the ABCD1 gene. Their brain function is normal at birth, but as the disease advances they develop progressive neurological symptoms. This is because VLCFAs accumulate and lead to demyelination, the loss of the protective cover around nerve cell fibers.
No cure for ALD currently exists, but there are treatments that can slow disease progression. Early diagnosis is key, preferably before neurological symptoms appear so that treatment might prevent damage to nerve cells.
This is why some states in the U.S. and some countries in Europe have instituted newborn screening for ALD.
What is newborn screening?
At birth, hospitals test every baby for a number of disorder that can affect them later in life. Called newborn screening, they usually do this test within a day or so of birth, before the baby goes home.
A small blood sample (usually collected from a heel stick) is taken for use in a series of metabolic tests. Genetic testing is not part of the typical newborn screening. However, parents can request a genetic test if they know their child may be at high risk for a particular disease due to family history.
The list of conditions screened for can vary by state in the U.S., although there are federal guidelines. These guidelines are called the Recommended Uniform Screening Panel, or RUSP.
How does the test for ALD work?
The test for ALD has three parts, although some laboratories can use slightly different tests. The blood sample from the baby is analyzed to determine whether VLCFA levels are high. If this first test does not detect these molecules, the result is negative.
If VLCFA levels are high, the sample is analyzed with a more sensitive instrument that takes longer. A second blood sample may be required for this test. Should levels of VLCFA also be high with this more sensitive analysis, a genetic test for mutations in the ABCD1 gene is necessary.
If the ABCD1 gene is normal, the baby may have one of a number of different conditions that could cause VLCFA levels to be elevated. In such cases, further testing will be necessary.
What happens after a positive test?
Your hospital or primary care physician will contact you if additional tests are necessary to confirm an ALD diagnosis. They will discuss treatment options with you, as well as a testing schedule for symptoms of ALD. Your doctor may also recommend that other family members undergo genetic testing to determine if they are carriers of this disease.
Last updated: April 28, 2020
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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.
