Adrenoleukodystrophy: Types, Causes, and Symptoms

Medical content synthesized from reputable U.S. resources, including NIH/NCBI GeneReviews,
MedlinePlus Genetics, HRSA Neveland Clinic,
Johns Hopkins Medicine, Kennedy Krieger Institute, Children’s Hospital of Philadelphia,
Boston Children’s Hospital, GARD, NORD, and ALD Connect.

Adrenoleukodystrophy is a long word for a rare genetic condition with an equally complicated personality. It can affect the brain, spinal cord, peripheral nerves, and adrenal glands, but it does not behave the same way in every person. One child may develop learning and behavioral changes, an adult may notice gradually worsening leg stiffness, and another person may have adrenal insufficiency before any neurological problem appears.

Most discussions of adrenoleukodystrophy refer to X-linked adrenoleukodystrophy, commonly shortened to X-ALD or simply ALD. The condition is caused by changes in the ABCD1 gene and is associated with the buildup of very long-chain fatty acids. These fats can damage myelin, the protective insulation around nerve fibers, and interfere with the adrenal glands’ ability to produce essential hormones.

What Is Adrenoleukodystrophy?

Adrenoleukodystrophy belongs to a family of disorders known as leukodystrophies. These conditions affect white matter, the network of myelin-covered nerve fibers that helps different parts of the nervous system communicate. Myelin works somewhat like insulation around an electrical wire. When it deteriorates, messages may travel slowly, arrive distorted, or fail to arrive at all.

In X-ALD, the adrenal cortex can also be damaged. The adrenal cortex is the outer portion of the adrenal glands, which sit above the kidneys and produce hormones such as cortisol. Cortisol helps regulate blood pressure, metabolism, blood sugar, inflammation, and the body’s response to illness or physical stress. When cortisol production falls too low, ordinary problems such as fever, vomiting, or injury can become much more dangerous.

ALD affects approximately 1 in 15,000 people worldwide and occurs across populations. Because the responsible gene is located on the X chromosome, boys and men are generally at greater risk of early and severe disease. However, girls and women with an ABCD1 variant are not merely unaffected “carriers.” Many eventually develop spinal cord-related symptoms, particularly later in adulthood.

X-ALD affects the nervous system and adrenal cortex, with a broad range of presentations.

An Important Naming Clarification

Neonatal adrenoleukodystrophy sounds as though it should be the newborn form of X-ALD, but it is actually a different disorder. Neonatal adrenoleukodystrophy is now classified within the Zellweger spectrum of peroxisome biogenesis disorders. It can affect infants of either sex and has different genetic causes.

That distinction matters because outdated terminology can create confusion for families reading test results or searching online. In this article, the term adrenoleukodystrophy refers to X-linked ALD unless neonatal ALD is specifically mentioned. Medical vocabulary occasionally keeps an old label around like a mystery container in the freezer: familiar-looking, poorly labeled, and capable of causing unnecessary confusion.

Neonatal adrenoleukodystrophy is distinct from X-linked ALD and belongs to the Zellweger spectrum.

What Causes X-Linked Adrenoleukodystrophy?

X-ALD is caused by a disease-causing variant in the ABCD1 gene. This gene provides instructions for making adrenoleukodystrophy protein, also called ALDP. The protein sits in the membrane of cellular structures known as peroxisomes.

Peroxisomes function partly as cellular processing and recycling centers. ALDP transports very long-chain fatty acids, or VLCFAs, into peroxisomes so they can be broken down. When ALDP is missing or does not work correctly, that transportation system stalls. The result is a fatty-acid traffic jam: VLCFAs accumulate in the blood and tissues, particularly in the nervous system, adrenal cortex, and testes.

The buildup of VLCFAs is associated with damage to myelin and adrenal tissue. In cerebral ALD, inflammatory activity in the brain contributes to rapid demyelination. In adrenomyeloneuropathy, degeneration mainly affects long nerve pathways in the spinal cord. Scientists still do not fully understand why one person develops aggressive cerebral disease while another relative with the same genetic variant develops milder symptoms decades later.

Severity Cannot Be Reliably Predicted From the Gene Variant

One of the most challenging facts about X-ALD is that the specific ABCD1 variant does not reliably predict the clinical outcome. VLCFA levels, family history, and the type of genetic change cannot tell doctors with certainty whether an individual will develop cerebral disease, adrenal insufficiency, adrenomyeloneuropathy, or few symptoms for many years.

Different forms may occur among relatives who carry the same variant. This unpredictability is why ongoing monitoring matters even when a newborn or newly diagnosed family member appears perfectly healthy.

ABCD1 variants disrupt ALDP-mediated VLCFA transport, and genotype does not reliably predict phenotype.

How Is Adrenoleukodystrophy Inherited?

X-ALD follows an X-linked inheritance pattern. Males usually have one X chromosome and one Y chromosome. A male who inherits an X chromosome carrying a disease-causing ABCD1 variant does not have a second copy of the gene to compensate, so he is considered affected.

Females usually have two X chromosomes. A female with an ABCD1 variant on one X chromosome may have fewer symptoms when she is young, but her risk of spinal cord and mobility problems rises with age.

• A woman with an ABCD1 variant has a 50% chance of passing that variant to each child.
• A son who inherits the variant is at risk of the full spectrum of X-ALD.
• A daughter who inherits it may develop neurological symptoms later in life.
• An affected father passes the variant to all his daughters and none of his sons.
• The absence of a known family history does not rule out ALD.

Once an ABCD1 variant is identified, genetic counseling can help relatives understand testing options, reproductive choices, and which family members may need medical surveillance.

Types and Clinical Forms of X-ALD

Doctors increasingly describe the “types” of ALD as phenotypes, meaning recognizable patterns of symptoms. These patterns can overlap, and the same person may develop more than one during a lifetime.

Childhood Cerebral Adrenoleukodystrophy

Childhood cerebral ALD is the most aggressive form. It most commonly begins between ages 4 and 8, although onset can occur earlier or later. Approximately one-third of boys with X-ALD develop cerebral disease.

The first signs may be surprisingly subtle. A child who previously performed well in school may become distracted, withdrawn, impulsive, or unusually aggressive. Handwriting may deteriorate. Reading comprehension, spatial awareness, memory, and the ability to understand spoken language may decline.

Because early symptoms can resemble attention-deficit/hyperactivity disorder, emotional stress, hearing problems, or an ordinary academic slump, families may not immediately suspect a neurological disease. As cerebral demyelination advances, symptoms may include poor coordination, visual impairment, hearing difficulties, weakness, swallowing problems, seizures, loss of communication, and severe disability.

Progression varies, but untreated active cerebral ALD can worsen rapidly. A brain MRI may show substantial white-matter abnormalities even when outward symptoms remain relatively mild.

Adolescent and Adult Cerebral ALD

Cerebral inflammatory disease can begin during adolescence or adulthood. Early features may include personality changes, depression, impulsive behavior, psychosis, declining judgment, memory loss, or difficulty performing familiar tasks. Neurological problems such as impaired coordination, speech changes, vision loss, or seizures may follow.

Adult cerebral ALD can occur on its own or develop in a person who already has adrenomyeloneuropathy. Sudden behavioral or cognitive decline in someone with a known ABCD1 variant should therefore be assessed promptly rather than being automatically blamed on stress, aging, or “just having a rough month.”

Adrenomyeloneuropathy

Adrenomyeloneuropathy, or AMN, is the most common neurological presentation in adult men with X-ALD. Symptoms typically begin in the 20s, 30s, or later and progress over years or decades.

AMN primarily affects the spinal cord and peripheral nerves. Common symptoms include:

• Progressive stiffness or weakness in the legs
• A stiff, awkward, or unsteady gait
• Frequent tripping or difficulty climbing stairs
• Muscle spasms and increased muscle tone
• Numbness, tingling, pain, or reduced vibration sensation
• Urinary urgency, retention, or incontinence
• Bowel urgency, constipation, or incontinence
• Erectile or other sexual dysfunction
• Fatigue and reduced endurance

Some men with AMN eventually develop cerebral involvement, making continued neurological assessment important even when symptoms have progressed slowly for many years.

Adrenal-Insufficiency-Only ALD

Some boys and men initially develop adrenal insufficiency without obvious neurological symptoms. This presentation has historically been called Addison-only ALD.

Possible symptoms include chronic fatigue, muscle weakness, poor appetite, weight loss, nausea, abdominal discomfort, recurrent vomiting, low blood pressure, low blood sugar, salt cravings, and increased skin pigmentation. The skin may appear unusually tan or darkened, especially around scars, skin folds, knuckles, elbows, knees, or gums.

Adrenal insufficiency may precede neurological disease by years or decades. A boy or man with unexplained primary adrenal insufficiency should be evaluated for X-ALD, particularly when autoimmune causes are not established.

Asymptomatic X-ALD

Many people are diagnosed before symptoms appear through newborn screening or family testing. “Asymptomatic” describes the person’s current condition, not a permanent guarantee. A healthy infant with an ABCD1 variant may remain well for years, but scheduled brain MRI studies, adrenal testing, and clinical examinations are necessary to identify changes early.

ALD in Girls and Women

Girls with an ABCD1 variant are generally symptom-free during childhood. In adulthood, many women develop an AMN-like condition involving the spinal cord. Symptoms may include leg stiffness, balance problems, falls, weakness, neuropathic pain, urinary difficulties, bowel urgency, and sexual dysfunction.

Progression in women is usually slower than in men with AMN. Cerebral ALD and adrenal insufficiency are rare in women, although unusual cases can occur. Because symptoms may emerge gradually, they are sometimes attributed to arthritis, aging, back trouble, or lack of fitness before the underlying neurological pattern is recognized.

Major Symptoms by Body System

Brain-Related Symptoms

• Declining school performance
• Loss of previously acquired skills
• Behavioral or personality changes
• Poor attention, memory, or judgment
• Difficulty reading, writing, or understanding language
• Vision or hearing problems
• Clumsiness and impaired coordination
• Speech or swallowing difficulties
• Seizures
• Progressive cognitive impairment

Spinal Cord and Peripheral Nerve Symptoms

• Leg stiffness and weakness
• Muscle spasms
• Walking difficulty
• Frequent falls
• Pain, numbness, or tingling
• Bladder or bowel dysfunction
• Sexual dysfunction

Adrenal Symptoms

• Persistent fatigue
• Unexplained weight loss
• Poor appetite
• Nausea or vomiting
• Abdominal pain
• Low blood pressure or dizziness
• Darkening of the skin
• Low blood sugar
• Difficulty recovering from illness

An adrenal crisis is a medical emergency. Severe weakness, repeated vomiting, dehydration, confusion, fainting, very low blood pressure, or loss of consciousness requires immediate emergency care, especially in someone with known or suspected adrenal insufficiency.

Symptoms differ across cerebral ALD, AMN, adrenal insufficiency, and female presentations.

How Is Adrenoleukodystrophy Diagnosed?

Newborn Screening

X-ALD is included on the U.S. Recommended Uniform Screening Panel, although screening practices can still vary by state. A few drops of blood collected from a newborn’s heel are tested for an elevated fatty-acid marker called C26:0-lysophosphatidylcholine.

An out-of-range screening result is not a final diagnosis. Follow-up may include repeat biochemical testing and analysis of the ABCD1 gene. Screening can identify risk before symptoms appear, but it cannot predict which clinical form a baby will develop.

Blood and Genetic Tests

Blood tests can measure VLCFAs and related biomarkers. Molecular genetic testing is used to identify a disease-causing ABCD1 variant. Genetic confirmation is especially important for testing relatives and establishing a long-term monitoring plan.

Brain MRI

MRI can detect characteristic white-matter changes and inflammatory activity associated with cerebral ALD. Regular MRI surveillance in at-risk boys can reveal early cerebral disease before major neurological symptoms appear. This window is crucial because treatments intended to slow cerebral progression work best before extensive damage has occurred.

Adrenal Testing

Doctors may measure morning cortisol and adrenocorticotropic hormone, commonly called ACTH. Additional endocrine testing may be required when results suggest adrenal insufficiency. Boys and men with X-ALD need repeated adrenal assessments even when they feel healthy.

Diagnosis involves newborn screening biomarkers, VLCFA testing, ABCD1 analysis, MRI, and adrenal evaluation.

Why Early Diagnosis and Monitoring Matter

There is no single treatment that cures every manifestation of X-ALD. However, early diagnosis can dramatically change what doctors are able to do.

Adrenal insufficiency can usually be managed with prescribed corticosteroid replacement. Families also receive instructions for stress dosing during fever, surgery, injury, or other physical stress. Correct hormone treatment can prevent adrenal crises, but it does not stop cerebral or spinal cord disease.

For carefully selected patients with early active cerebral ALD, an allogeneic hematopoietic stem cell transplant may slow or halt further inflammatory demyelination. The procedure carries significant risks and is most beneficial when MRI abnormalities are detected early and major neurological disability has not developed. It cannot reliably restore brain function that has already been lost.

The FDA-approved gene therapy elivaldogene autotemcel, sold as Skysona, is indicated for certain boys ages 4 through 17 with early active cerebral ALD who do not have an available HLA-matched donor for allogeneic stem cell transplantation. In August 2025, the FDA required stronger labeling because of an increased risk of serious blood cancers following treatment. Decisions about gene therapy therefore require detailed discussion of eligibility, alternatives, immediate risks, long-term risks, and lifelong follow-up.

AMN treatment is generally supportive and may include physical therapy, treatment for spasticity or pain, mobility aids, bladder and bowel care, occupational therapy, and psychological support. A multidisciplinary team can address several problems without expecting one specialist to wear twelve medical hats at once.

Early cerebral disease may be treated with transplant or selected gene therapy; FDA updated Skysona safety labeling in 2025.

When Should Someone Be Evaluated?

Medical evaluation is appropriate when a child develops unexplained regression in school performance, handwriting, behavior, vision, hearing, coordination, or language comprehension. Adults should seek assessment for progressive leg stiffness, repeated falls, bladder changes, neuropathic pain, or unexplained cognitive and behavioral symptoms.

Testing may also be appropriate when a boy or man has unexplained primary adrenal insufficiency or when any relative is diagnosed with an ABCD1 variant. Family screening can identify relatives who need adrenal monitoring and brain MRI surveillance before serious symptoms develop.

Experiences Families and Individuals May Encounter

The following examples are representative composite scenarios based on common clinical and caregiving experiences. They do not describe one specific patient and should not be interpreted as personal medical testimony.

The Newborn Screening Experience

For many families, the experience begins with a phone call about an out-of-range newborn screening result. The baby may look healthy, feed normally, and behave exactly like a newborn whose primary hobbies are sleeping at unpredictable times and demanding room service. That contrast can make the result difficult to process. Parents may wonder how a serious condition can be present when nothing appears wrong.

The next stage often includes repeat blood tests, genetic testing, specialist appointments, and testing of relatives. This period can bring both anxiety and uncertainty because confirmation of an ABCD1 variant does not reveal exactly what the child’s future will look like. A care plan may involve years of routine adrenal tests and scheduled MRIs. Although monitoring can feel burdensome, it creates an opportunity to detect treatable complications before symptoms become obvious.

When School Problems Are the First Clue

Another common experience involves a school-age boy who begins struggling with tasks he once handled easily. Teachers may notice poor concentration, declining handwriting, forgotten instructions, or unusual behavior. Parents may initially suspect ADHD, bullying, hearing loss, stress, or a learning disability. Those are far more common explanations, so ALD may not be considered immediately.

What raises concern is a pattern of regression rather than a stable learning difference. A child may lose skills, misunderstand familiar speech, bump into objects, or become increasingly withdrawn or impulsive. Families sometimes describe the diagnostic period as emotionally disorienting because the child still appears physically healthy while MRI findings reveal active brain disease. Rapid referral to an experienced leukodystrophy center becomes especially important at this point.

Living With Slowly Progressive AMN

Adults with AMN often face a different timeline. Symptoms may build so gradually that the person adapts without realizing how much has changed. They may avoid stairs, choose seats near restrooms, stop walking long distances, or blame repeated tripping on shoes and uneven sidewalks. Bladder symptoms and sexual dysfunction may be especially difficult to discuss, which can delay care.

A diagnosis may bring relief because it finally connects problems that seemed unrelated. It can also introduce practical questions about employment, driving, home accessibility, mobility aids, relationships, and future independence. Physical therapy and assistive devices are not signs of giving up; they are tools for preserving energy, safety, and participation in daily life.

The Experience of Women With ALD

Women with an ABCD1 variant may spend years being described as carriers and then feel surprised when leg stiffness, pain, urinary urgency, or balance problems emerge. Some report that their symptoms were initially minimized because ALD was viewed primarily as a childhood disease affecting boys.

Recognition that women can develop genuine neurological disease is important. Even when progression is slower, symptoms can meaningfully affect work, exercise, sleep, family responsibilities, and emotional well-being. Care may involve neurology, rehabilitation medicine, urology, pain management, and genetic counseling.

Managing the Emotional Side of Uncertainty

Perhaps the most universal experience is uncertainty. Family members with the same genetic variant can have dramatically different symptoms. Parents may feel tempted to watch every stumble or forgotten homework assignment as though it were a medical alarm. Adults may worry about whether a new ache signals progression.

A structured surveillance plan can reduce some of this pressure. Instead of relying on constant vigilance, families can use scheduled evaluations, written emergency instructions, reliable medical contacts, and clear guidance about which changes require urgent attention. Support groups, rare-disease organizations, counseling, and communication with schools or employers can also help transform uncertainty from an all-day emergency into something more manageable.

Conclusion

Adrenoleukodystrophy is not one predictable illness with one fixed set of symptoms. X-ALD can appear as rapidly progressive cerebral disease, slowly developing adrenomyeloneuropathy, adrenal insufficiency, adult neurological symptoms in women, or an asymptomatic condition discovered through screening.

The underlying cause is a disease-causing ABCD1 variant that disrupts the processing of very long-chain fatty acids. Yet the gene variant alone cannot reliably predict who will develop each form. That makes newborn screening, family testing, adrenal surveillance, neurological examinations, and scheduled brain MRI studies essential parts of care.

Early recognition matters most in cerebral ALD, where the window for disease-modifying treatment may close after significant neurological damage develops. It also matters in adrenal insufficiency, where appropriate hormone replacement can prevent a life-threatening crisis. A rare diagnosis may come with an intimidating name, but informed monitoring gives families something extremely valuable: the ability to act before the disease makes the first move.