Adrenoleukodystrophy

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Adrenoleukodystrophy (ALD) is a degenerative disorder of myelin, a complex fatty neural tissue that insulates many nerves of the central and peripheral nervous systems. Without myelin, nerves are unable to conduct an impulse, leading to increasing disability as myelin destruction increases and intensifies. The victims of ALD are always male, and the disease begins its expression around the ages 5 to 10. The disease is due to an X-linked inheritance of peroxisomes that cannot properly process long chain fatty acids in the brain.

ALD is a type of leukodystrophy, disorders affecting the growth and/or development of myelin. Leukodystrophies are different from demyelinating disorders such as multiple sclerosis where myelin is formed normally but is lost by immunologic dysfunction or for other reasons.

Adrenoleukodystrophy was first described by Siemerling and Creutzfeld in 1923. The X-linked recessive inheritance phenomenon was clarified in 1963 by Fanconi et al. This was previously known as Schilder ‘s syndrome, but in 1970 Michael Blaw renamed it to “Adrenoleukodystrophy.” Fanconi et al . discovered the X-linked recessive inheritance in 1963. In 1976, Igarashi et al identified the aggregation of concentrated, very long chain fatty acids (VLCFAs) in brain and adrenal tissue. In 1986, Lazo et al. indicated that incomplete oxidation of fatty acids is due to the deficiency of the peroxisome matrix enzyme lignoceroyl-CoA synthetase. Mosser et al. isolated the ALD gene in 1993.

Adrenoleukodystrophy may be classified based on different clinical presentations. There are seven male phenotypes i.e. Childhood cerebral adrenoleukodystrophy, Adolescent, Adrenomyeloneuropathy, Adult cerebral, Olivo-pontocerebellar, Addison-only , Asymptomatic and five female phenotypes i.e. Asymptomatic, Mild myelopathy, Moderate to severe myeloneuropathy, Cerebral involvement, Clinically evident adrenal insufficiency.

Adrenoleukodystrophy is an X-linked disease characterized by excessive accumulation of very long chain fatty acids (VLCFA), originally described by Moser et al in 1981. The gene (ABCD1 or “ATP-binding cassette, subfamily D, member 1”) codes for a protein that transfers fatty acids into peroxisomes, the cellular organelles where the fatty acids undergo β-oxidation. A dysfunctional gene leads to the accumulation of very long chain fatty acids (VLCFA). However, VLCFA accumulation is necessary but not sufficient for the pathogenesis. Pathology in CNS shows distinct immunological features. A predominant Th1 cytokine response suggests the role of cell mediated immunity. Immunocytochemical analysis done on the CSF from the ALD patients showed IgG, B cells and the presence of cytoplasmic IgA in postmortem brain suggesting the role of the humoral immune process. There was increased expression of the antigen-presenting molecule, which presents foreign and self-lipid to MHC-unrestricted T cells, CD1 in cerebral lesions clearly showing that both VLCFA and a myelin component such as proteolipid protein serves as the antigen for the immune response.  TNF-alpha also has an important role in the pathogenesis of ALD. On Gross Examination Adrenal glands show atrophy, Brain shows visible demyelination involving both cerebellar hemispheres, parts of the medulla oblongata, the pons and the midbrain and Spinal cord shows grayish white matter area. On microscopic examination adrenal medulla appears fine, but the cortex is atrophic. A substantial portion of it is replaced by clusters of extremely large cells, distinctly delimited from each other, with mildly granular eosinophilic cells and Cytoplasm and a nucleus moderately rich in chromatin shifted towards the cytoplasma membrane. Whereas nervous system shows Nearly complete demyelination affecting all white structures in the dorsal areas of the brain, Complete demyelination of the cerebellar hemispheres, prefrontal peduncles, pes pontis, pyramids and lateral pyramidal tract, Gliosis and macrophages are present, Glial cells are found in myelinated and unmyelinated regions, Abnormalities are found in the schwann cells of the peripheral nerve, Changes in the gray matter are less apparent than those in white matter but some of the pathological findings present include: Proximal Axonal Swellings in Purkinje cell axons, Ballooned nerve cells in the arcuate nucleus of the medulla oblongata and Granular cellular content and nucleus displaced towards the periphery.

X-linked adrenoleukodystrophy (X-ALD) is a monogenic disease caused by mutations in the ABCD1 gene located on Xq28. It is passed down from parents to their children as an X-linked genetic trait. It therefore affects mostly males, although some women who are carriers can have milder forms of the disease. The condition results in the buildup of very-long-chain fatty acids in the nervous system, adrenal gland, and testes, which disrupts normal activity.

Adrenoleukodystrophy must be differentiated from Leigh syndrome, Niemann-Pick disease type C, Infantile Refsum disease, Zellweger syndrome, Pyruvate dehydrogenase deficiency, Arginase deficiency, Holocarboxylase synthetase deficiency, Glutaric aciduria type 1, Ataxia telangiectasia, Pontocerebellar hypoplasias, Metachromatic leukodystrophy, Pelizaeus-Merzbacher, Angelman syndrome, Rett syndrome, Lesch-Nyhan syndrome, Miller-Dieker lissencephaly and Dopa-responsive dystonia.

Adrenoleukodystrophy is the most common peroxisomal disorder, with an estimated incidence of 1 in 17,000 births (male and female) and 1 in 21,000 males in the United States. The prevalence of X-linked adrenoleukodystrophy is approximately 1 in 20,000 individuals. This condition occurs at a similar frequency in all populations. The lifetime prevalence of adrenal insufficiency in ALD is ~80 percent. Childhood cerebral type is common in age 3-10 years. The median age of the AMN form is 28 years. Addison disease type occurs at 0 to (greater or equal to) 10 years of age. Cerebellar type can occur in childhood or adolescence. There is no race predilection for adrenoleukodystrophy. Men are more likely to be affected by adrenoleukodystrophy than women. Women can, however, be the carriers of the disease.

Adrenoleukodystrophy is a inherited disease, and someone with a family history of illness is at risk. Because the disorder is passed by parents to their offspring as an X-linked genetic mutation, males are mainly affected, while some females may have signs of the disease but are mostly asymptomatic carriers.

Adrenoleukodystrophy screening started in state of New York in December, 2013 followed by Connecticut, California, Minnesota and 14 other states. The first step in screening is to take newborn’s dried blood spot and analyse it with tandem mass spectrometry for the elevated levels of C26:0-LPC. Samples with a high concentration of C26:0-LPC are then tested in the second step with a more sensitive but time consuming test, using High Performance Liquid Chromatography – MS / MS. The third step is the sequencing of the ABCD1 gene in those samples which still shows elevated C26:0-LPC.

Adrenoleukodystrophy is a progressive disease as the risk of symptoms increases with age but its manifestations are highly variable. Most of the male patients presents with adrenal insufficiency (Addison disease) in childhood (80% prevalence) while those in adulthood presents with signs of myelopathy. Women with the ALD usually presents with myelopathy, other manifestations such as adrenal insufficiency are unusual. Childhood cerebral ALD is the most serious form of the disease. It typically occurs between the ages of 2.5 and 10 years, and is associated with rapid neurological decline and death or disability on average 3 years after initiation. Males who do not develop the disease in childhood, develops Adrenomyeloneuropathy (AMN) in 30s or 40s. ALD usually does not occur in heterogeneous women. Only 88 per cent of adult women can become symptomatic with myelopathy and peripheral neuropathy, but the symptoms are usually milder than those of men.

Common complications of Adrenoleukodystrophy include Adrenal crisis and Vegetative state (long-term coma).

The childhood form of X-linked adrenoleukodystrophy is a progressive disease that leads to a long-term coma (vegetative state) about 2 years after neurological symptoms develop. The child can live in this condition for as long as 10 years until death occurs. The other forms of this disease are milder.

The clinical manifestations of the disease are highly variable, with at least six different types ranging from childhood cerebral to asymptomatic.The most severe type is the childhood cerebral form, which normally occurs in males between the ages of 5 and 10 and is characterized by failure to develop, seizures, ataxia, adrenal insufficiency, as well as degeneration of visual and auditory function. Frequent initial symptoms include emotional lability, hyperactive behaviour, school failure, impaired auditory discrimination and difficulties in vision. The adolescent type usually starts between age 11 and 21 years. Adrenomyeloneuropathy usually presents with weakness and numbness of the limbs and problems with urination or defecation. Some patients may present with sole findings of primary adrenal insufficiency.

Most males in childhood have adrenal insufficiency that can show orthostatic hypotension, hyperpigmentation and confusion. Females who are heterozygous and symptomatic can have sphincter disturbances, incoordination and paraparesis.The most aggressive one is Childhood cerebral type which can show behavioural changes, school failure, dementia, speech impairment, bulbar palsy, paralysis and audiovisual changes on examination. Some of the general examination findings which can occur in all phenotypes includes Strabismus, Swallowing difficulties, Aphasia, Deterioration of handwriting, Difficulty at school, Difficulty understanding spoken material, Hyperactivity,Coma, Decreased fine motor control,Paralysis, Seizures, Possible worsening muscle weakness or leg stiffness, Problems with thinking speed and visual memory.

An elevated concentration of plasma levels of VLCFA suggests the presence of Adrenoleukodystrophy. DNA-based diagnosis can be obtained to look for mutations in the ABCD1 gene in the case of carriers and is particularly important in the diagnosis of the disease in women. Assessment of physical capabilities and measurements of walking speed, hip strength, vibration sense and nerve conductions studies has been used in assessing disease severity in AMN.

Brain MRI may be helpful in the diagnosis of Adrenoleukodystrophy. Findings on MRI suggestive of Adrenoleukodystrophy include Abnormal bright signal intensities on the T2-weighted MRI images, Involvement of Corticospinal tracts is the most common finding in male patients whereas in females there is mild diffuse increase of signal intensity in the parieto occipital or frontal lobe white matter. Spine MRI may also be helpful in the diagnosis of Adrenoleukodystrophy. Findings on MRI suggestive of Adrenoleukodystrophy include Magnetization transfer-weighted (MTw) images showing signal hyperintensities in the lateral and dorsal columns and Diffuse spinal cord atrophy, mainly in the thoracic and cervical regions.

Brain CT scan may be helpful in the diagnosis of Adrenoleukodystrophy but not used as it is less sensitive than MRI. Findings on CT scan suggestive of Adrenoleukodystrophy can include Contrast enhancement within or adjacent to the abnormally hypodense deep white matter of the parietal, occipital lobes and at the interface between this active demyelinating area and uninvolved normal brain, Asymmetric areas of diminished attenuation in occipital horns of the lateral ventricles and the splenium of the corpus callosum.

This imaging technique show changes in metabolic rates. MRS imaging was able to demonstrate low NAA and high choline levels in white matter as a first indicator of metabolic dysfunction, prior to MRI changes in ALD.

This imaging technique show changes in water diffusion parameters. High directionality and structure of white matter, resulting from the directional morphology of myelinated axons, is quantified by a higher relative Fractional anisotropic (FA) with DTI. A decreased FA can be seen in central cALD lesion areas.

There are no other diagnostic studies associated with Adrenoleukodystrophy.

The mainstay of treatment for adrenoleukodystrophy is Hematopoietic stem cell transplantation. Supportive therapy includes Lorenzo’s oil and Lovastatin therapy. Antioxidant therapy has also shown some persuasive results demanding a larger study whereas treatment with Gene therapy including Ex vivo lentiviral gene correction and in vivo adeno-associated virus 9 (AAV9) based gene therapy is being pursued.

Surgical intervention is not recommended for the management of adrenoleukodystrophy.

There are no established measures for the primary prevention of adrenoleukodystrophy.

The objective of secondary prevention in adrenoleukodystrophy is to diagnose it early, preferably before neurological symptoms appear so as to prevent nerve cell damage from occurring, initiating timely adrenal steroid replacement therapy following detection of adrenal insufficiency, and for providing allogeneic hematopoietic stem cell transplantation (HSCT) as a means of treating cerebral ALD. In February 2016, adrenoleukodystrophy was added to the Recommended Uniform Screening Panel (RUSP) in the USA, which is the federal list of all genetic diseases recommended for state newborn screening programs.

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Adrenoleukodystrophy was first described by Siemerling and Creutzfeld in 1923. The X-linked recessive inheritance phenomenon was clarified in 1963 by Fanconi et al. This was previously known as Schilder ‘s syndrome, but in 1970 Michael Blaw renamed it to “Adrenoleukodystrophy.” Fanconi et al . discovered the X-linked recessive inheritance in 1963. In 1976, Igarashi et al identified the aggregation of concentrated, very long chain fatty acids (VLCFAs) in brain and adrenal tissue. In 1986, Lazo et al. indicated that incomplete oxidation of fatty acids is due to the deficiency of the peroxisome matrix enzyme lignoceroyl-CoA synthetase. Mosser et al. isolated the ALD gene in 1993.

• Initially it was described in germany by Siemerling and Creutzfeld in 1923. They called it Bronzekrankheitund Sklerosierende Encephalitis.
• Later on, it was designated as Schilder’s disease. But It was changed to “Adrenoleukodystrophy” by Michael Blaw in 1970.
• The X-linked recessive inheritance was revealed by Fanconi et al in 1963.
• In 1976, Igarashi et al described the accumulation of saturated very long chain fatty acids (VLCFAs) in brain and adrenal tissues.
• In 1986, Lazo et al. suggested that the impaired fatty acid oxidation is due to deficient function of the peroxisomal matrix enzyme lignoceroyl-CoA synthetase.
• In 1993, Mosser et al. isolated the ALD gene.

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Adrenoleukodystrophy may be classified based on different clinical presentations. There are seven male phenotypes i.e. Childhood cerebral adrenoleukodystrophy, Adolescent, Adrenomyeloneuropathy, Adult cerebral, Olivo-pontocerebellar, Addison-only , Asymptomatic and five female phenotypes i.e. Asymptomatic, Mild myelopathy, Moderate to severe myeloneuropathy, Cerebral involvement, Clinically evident adrenal insufficiency.

Adrenoleukodystrophy may be classified based on different clinical presentations. There are seven phenotypes described in males and five in females.^[1]

Phenotype in Males
Childhood Cerebral Adrenoleukodystrophy (CCER)
Adolescent
Adrenomyeloneuropathy (AMN)
Adult cerebral
Olivo-pontocerebellar
Addison-only
Asymptomatic
Phenotype in Females
Asymptomatic
Mild myelopathy
Moderate to severe myeloneuropathy
Cerebral involvement
Clinically evident adrenal insufficiency

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Adrenoleukodystrophy is an X-linked disease characterized by excessive accumulation of very long chain fatty acids (VLCFA), originally described by Moser et al in 1981. The gene, ABCD1, transfers fatty acids into peroxisomes to undergo β-oxidation. However, VLCFA accumulation is necessary but not sufficient for the pathogenesis. The CNS pathology suggests the role of cellular and humoral immune processes.

The most common form of ALD is X-linked (the defective gene is on the X chromosome, location Xq28), and is characterized by excessive accumulation of very long chain fatty acids (VLCFA) — fatty acids chains with 24–30 carbon atoms (particularly hexacosanoate, C26) in length. This was originally described by Moser et al in 1981.^[1] So, when the ALD gene was discovered in 1993, it was a surprise that the corresponding protein was in fact a member of a family of transporter proteins, not an enzyme. It is still a mystery as to how the transporter affects the function of the fatty acid enzyme and, for that matter, how high levels of very long chain fatty acids cause the loss of myelin on nerve fibers.

Pathology in CNS shows distinct immunological features. A predominant Th1 cytokine response suggests the role of cell mediated immunity. Immunocytochemical analysis done on the CSF from the ALD patients showed IgG, B cells and the presence of cytoplasmic IgA in postmortem brain suggesting the role of the humoral immune process. There was increased expression of the antigen-presenting molecule, which presents foreign and self-lipid to MHC-unrestricted T cells, CD1 in cerebral lesions clearly showing that both VLCFA and a myelin component such as proteolipid protein serves as the antigen for the immune response. ^[2] TNF-alpha also has an important role in the pathogenesis of ALD.

The gene (ABCD1 or “ATP-binding cassette, subfamily D, member 1”) codes for a protein that transfers fatty acids into peroxisomes, the cellular organelles where the fatty acids undergo β-oxidation.^[3] A dysfunctional gene leads to the accumulation of very long chain fatty acids (VLCFA).

• Adrenal glands show atrophy.
• Brain shows visible demyelination involving both cerebellar hemispheres, parts of the medulla oblongata, the pons and the midbrain.
• Spinal cord shows grayish white matter area.

Medulla appears fine, but the cortex is atrophic. A substantial portion of it is replaced by clusters of extremely large cells, distinctly delimited from each other, with mildly granular eosinophilic cells. Cytoplasm and a nucleus moderately rich in chromatin shifted towards the cytoplasma membrane.^[4]

• Nearly complete demyelination affecting all white structures in the dorsal areas of the brain.
• Complete demyelination of the cerebellar hemispheres, prefrontal peduncles, pes pontis, pyramids and lateral pyramidal tract.
• Gliosis and macrophages are present. Glial cells are found in myelinated and unmyelinated regions.
• Abnormalities are found in the schwann cells of the peripheral nerve.
• Changes in the gray matter are less apparent than those in white matter but some of the pathological findings present include:
  • Proximal Axonal Swellings in Purkinje cell axons
  • Ballooned nerve cells in the arcuate nucleus of the medulla oblongata
  • Granular cellular content and nucleus displaced towards the periphery

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X-linked adrenoleukodystrophy (X-ALD) is a monogenic disease caused by mutations in the ABCD1 gene located on Xq28. It is passed down from parents to their children as an X-linked genetic trait. It therefore affects mostly males, although some women who are carriers can have milder forms of the disease. The condition results in the buildup of very-long-chain fatty acids in the nervous system, adrenal gland, and testes, which disrupts normal activity.

Adrenoleukodystrophy is passed down from parents to their children as an X-linked genetic trait. It therefore affects mostly males, although some women who are carriers can have milder forms of the disease. It affects approximately 1 in 20,000 people from all races.

The condition results in the buildup of very-long-chain fatty acids in the nervous system, adrenal gland, and testes, which disrupts normal activity. There are different types of ALD, with a range of symptoms and differing ages of onset, but the underlying cause of the disease is the same in each type: a mutation, or a change, in the ABCD1 gene. ^[1] There are three major categories of disease:

• Childhood cerebral form — appears in mid-childhood (at ages 4 – 8)
• Adrenomyelopathy — occurs in men in their 20s or later in life
• Impaired adrenal gland function (called Addison disease or Addison-like phenotype) — adrenal gland does not produce enough steroid hormones

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Adrenoleukodystrophy must be differentiated from Leigh syndrome, Niemann-Pick disease type C, Infantile Refsum disease, Zellweger syndrome, Pyruvate dehydrogenase deficiency, Arginase deficiency, Holocarboxylase synthetase deficiency, Glutaric aciduria type 1, Ataxia telangiectasia, Pontocerebellar hypoplasias, Metachromatic leukodystrophy, Pelizaeus-Merzbacher, Angelman syndrome, Rett syndrome, Lesch-Nyhan syndrome, Miller-Dieker lissencephaly and Dopa-responsive dystonia.

Adrenoleukodystrophy must be differentiated from other diseases that cause neurological manifestations in infants.

Diseases	Type of motor abnormality				Clinical findings	Laboratory findings and diagnostic tests	Radiographic findings
	Spasticity	Hypotonia	Ataxia	Dystonia
Leigh syndrome	–	–	+	+	Progressive psychomotor regression Seizures External ophthalmoplegia Lactic acidosis Vomiting	Increased lactate levels in blood and CSF Genetic testing	MRI: abnormal white matter signal in the putamen, basal ganglia, and brainstem on T2 images
Niemann-Pick disease type C	–	–	+	+	Progressive neurodegeneration Hepatosplenomegaly Systemic involvement of liver, spleen, or lung preceedes neurologic symptoms	Abnormal liver function tests Fibroblast cell culture with filipin staining	MRI: Cerebral and cerebellar atrophy Thinning of the corpus callosum
Infantile Refsum disease	–	+	+	–	Abnormalities of the optic nerve and disc Retinitis pigmentosa Sensorineural hearing loss Hepatomegaly and cirrhosis Neurologic deterioration is slower than in Zellweger syndrome or ALD	Elevated plasma VLCFA levels	—
Adrenoleukodystrophy	+	–	–	–	Cognitive and behavioral abnormalities Adrenal insufficiency Hyperpigmented skin Gonadal dysfunction Neurologic deterioration progresses at a variable rate	Elevated plasma VLCFA levels Molecular genetic testing for mutations in the ABCD1 gene	—
Zellweger syndrome	–	+	–	–	Craniofacial dysmorphism Hepatomegaly Neonatal seizures Profound developmental delay MRI findings include cortical and white matter abnormalities Neurologic deterioration is rapid and infants rarely survive beyond six months of age	Elevated plasma VLCFA levels Elevated levels of phytanic acid, pristanic acid, and pipecolic acid in plasma and fibroblasts Reduced plasmalogen in erythrocytes Molecular genetic testing for mutations in the PEX1 or PEX6 genes	—
Pyruvate dehydrogenase deficiency	+	+	+	–	Lactic acidosis Seizures Intellectual disability	Elevated lactate and pyruvate levels in blood and CSF Abnormal PDH enzymatic activity in cultured fibroblasts	—
Arginase deficiency	+	–	–	–	Hyperammonemia Encephalopathy Respiratory alkalosis	Elevated ammonia level Elevated arginine level	—
Holocarboxylase synthetase deficiency	–	+	–	–	Ketoacidosis Dermatitis Alopecia Seizures Developmental delay	Elevated levels of: Beta-hydroxyisovalerate Beta-methylcrotonylglycine Beta-hydroxypropionate Methylcitrate Tiglylglycine	—
Glutaric aciduria type 1	–	–	–	+	Episodes of metabolic decompensation and encephalopathy often precipitated by infection and fever Rarely presents in the newborn period Microencephalic macrocephaly Seizures (approximately 20 percent) Cognitive function is preserved	Elevated levels of: glutaric acid 3-hydroxyglutaric acid	MRI: Frontal and temporal atrophy
Ataxia telangiectasia	–	–	+	–	Progressive cerebellar ataxia Abnormal eye movements Oculocutaneous telangiectasias Immune deficiency Increased risk of malignancy	Elevated serum alpha-fetoprotein level Low IgA and IgG levels Lymphopenia Genetic testing for mutation in the ATM gene	—
Pontocerebellar hypoplasias	–	+	–	–	Progressive muscle atrophy Microcephaly Developmental delay	Genetic testing for PCH gene mutations	MRI : Small cerebellum and brainstem including the pons
Metachromatic leukodystrophy	–	+	+	–	Regression of motor skills Seizures Optic atrophy Reduced or absent deep tendon reflexes Intellectual disability	Deficient arylsulfatase A enzyme activity in leukocytes or cultured skin fibroblasts	—
Pelizaeus-Merzbacher	+	–	+	–	Nystagmus Cognitive impairment Onset in infancy Slowly progressive Language development may be normal	Genetic testing for mutations in PLP1 gene	MRI: White matter abnormalities
Angelman syndrome	–	–	+	–	Profound intellectual disability Postnatal microcephaly Typical abnormal behaviors (paroxysmal laughter, easily excitable)	Methylation studies and chromosome microarray to detect chromosome 15 anomalies and UBE3A mutations	—
Rett syndrome	+	–	–	+	Occurs almost exclusively in females Normal development during first six months followed by regression and loss of milestones Loss of speech capability Stereotypic hand movements Seizures Autistic features	Clinical diagnosis Genetic testing for MECP2 mutations	—
Lesch-Nyhan syndrome	+	–	–	+	Self-mutilating behavior Urinary stones due to hyperuricemia	Elevated uric acid level Abnormal enzymatic activity of HPRT in cultured fibroblasts Genetic testing for HPRT gene mutations	—
Miller-Dieker lissencephaly	+	+	–	–	Lissencephaly Microcephaly Dysmorphic features Seizures Failure to thrive	Cytogenetic testing for 17p13.3 microdeletion	—
Dopa-responsive dystonia	+	–	–	+	Onset in early childhood Symptoms worsen with fatigue and exercise	Positive response to a trial of levodopa	—

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Adrenoleukodystrophy is the most common peroxisomal disorder, with an estimated incidence of 1 in 17,000 births (male and female) and 1 in 21,000 males in the United States. The prevalence of X-linked adrenoleukodystrophy is approximately 1 in 20,000 individuals. This condition occurs with a similar frequency in all populations. The lifetime prevalence of adrenal insufficiency in ALD is ~80%.

• Adrenoleukodystrophy is the most common peroxisomal disorder, with an estimated incidence of 1 in 17,000 births (male and female) and 1 in 21,000 males in the United States. ^[1]

• The prevalence of X-linked adrenoleukodystrophy is approximately 1 in 20,000 individuals. This condition occurs with a similar frequency in all populations.

• The lifetime prevalence of adrenal insufficiency in ALD is ~80%. ^[2]

• Childhood cerebral type commonly occurs in 3-10 years of age.^[3]
• AMN type has a median age of 28 years.^[3]
• Addison disease type occurs in 0 to (greater or equal to) 10 years of age.^[3]
• Cerebellar type can occur in childhood or adolescence.

There is no racial predilection to adrenoleukodystrophy.

• Men are more commonly affected by adrenoleukodystrophy than women. However, women can be a carrier of the disease.

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Adrenoleukodystrophy is a inherited disease, and someone with a family history of illness is at risk. Because the disorder is passed by parents to their offspring as an X-linked genetic mutation, males are mainly affected, while some females may have signs of the disease but are mostly asymptomatic carriers.

Adrenoleukodystrophy is a inherited disease, and someone with a family history of illness is at risk. Because the disorder is passed by parents to their offspring as an X-linked genetic mutation, males are mainly affected, while some females may have signs of the disease but are mostly asymptomatic carriers.

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Adrenoleukodystrophy screening started in state of New York in December, 2013 followed by Connecticut, California, Minnesota and 14 other states. The first step in screening is to take newborn’s dried blood spot and analyse it with tandem mass spectrometry for the elevated levels of C26:0-LPC. Samples with a high concentration of C26:0-LPC are then tested in the second step with a more sensitive but time consuming test, using High Performance Liquid Chromatography – MS / MS. The third step is the sequencing of the ABCD1 gene in those samples which still shows elevated C26:0-LPC.

• Before the start of newborn screening for adrenoleukodystrophy only males were diagnosed based on their positive family history for the disease or during the initial work-up for primary adrenal insufficiency. New York became the first state to start the newborn screening for X-ALD in Dec, 2013 followed by Connecticut, California, Minnesota and 14 other states. ^[1]

• Early diagnosis has to be of direct benefit to the newborn. Health gains must be significant, accomplished by early intervention in serious diseases with a known natural course.
• There has to be a high quality screening test. The assay must be highly specific and sensitive, meaning it has a very low rate of both false positive and false negative outcomes.

• The first step is tandem mass spectrometry for C26:0-LPC analysis. Samples with a high concentration of C26:0-LPC are then tested in the second step with a more sensitive but time consuming test, using High Performance Liquid Chromatography – MS / MS. The third step is the sequencing of the ABCD1 gene in those samples which still shows elevated C26:0-LPC.^[2]

Adrenoleukodystrophy Screening

Newborn Bloodspot

Tandem mass spectrometry for C26:0-LPC (MS/MS)

High Performance Liquid Chromatography–MS/MS for C26:0-LPC

ABCD1 gene sequencing

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Adrenoleukodystrophy is a progressive disease as the risk of symptoms increases with age but its manifestations are highly variable. Most of the male patients presents with adrenal insufficiency (Addison disease) in childhood (80% prevalence) while those in adulthood presents with signs of myelopathy. Childhood cerebral ALD is the most serious form of the disease. It typically occurs between the ages of 2.5 and 10 years, and is associated with rapid neurological decline and death or disability on average 3 years after initiation. Males who do not develop the disease in childhood, develops Adrenomyeloneuropathy (AMN) in 30s or 40s.

• Adrenoleukodystrophy is a progressive disease as the risk of symptoms increases with age but its manifestations are highly variable.

• Most of the male patients presents with adrenal insufficiency (Addison disease) in childhood (80% prevalence) while those in adulthood presents with signs of myelopathy. Women with the ALD usually presents with myelopathy, other manifestations such as adrenal insufficiency are unusual. ^[1]

• Childhood cerebral ALD is the most serious form of the disease. It typically occurs between the ages of 2.5 and 10 years, and is associated with rapid neurological decline and death or disability on average 3 years after initiation.

• Males who do not develop the disease in childhood, develops Adrenomyeloneuropathy (AMN) in 30s or 40s.

• ALD usually does not occur in heterogeneous women. Only 88 per cent of adult women can become symptomatic with myelopathy and peripheral neuropathy, but the symptoms are usually milder than those of men.^[2]

• Common complications of Adrenoleukodystrophy include:
  • Adrenal crisis
  • Vegetative state (long-term coma)

The childhood form of X-linked adrenoleukodystrophy is a progressive disease that leads to a long-term coma (vegetative state) about 2 years after neurological symptoms develop. The child can live in this condition for as long as 10 years until death occurs.

The other forms of this disease are milder.

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