Progression of abnormalities in adrenomyeloneuropathy and neurologically asymptomatic X-linked adrenoleukodystrophy despite treatment with "Lorenzo's oil"

Practical Approach to Longitudinal Neurologic Care of Adults With X-Linked Adrenoleukodystrophy and Adrenomyeloneuropathy

Although X-linked adrenoleukodystrophy (ALD) has historically been considered a childhood disease managed by pediatric neurologists, it is one of the most common leukodystrophies diagnosed in adulthood. An increase in both male and female adults reaching diagnosis due to familial cases identified by state newborn screening panels and more widespread use of genetic testing results in a large cohort of presymptomatic or early symptomatic adults. This population is in urgent need of standardized assessments and follow-up care. Adults with ALD/adrenomyeloneuropathy (AMN) may be diagnosed in a variety of ways, including after another family member is identified via genetic testing or newborn screening, presenting for symptomatic evaluation, or following diagnosis with primary adrenal insufficiency. Significant provider, patient, and systems-based barriers prevent adult patients with ALD/AMN from receiving appropriate care, including lack of awareness of the importance of longitudinal neurologic management. Confirmation of and education about the diagnosis should be coordinated in conjunction with a genetic counselor. Routine surveillance for adrenal insufficiency and onset of cerebral ALD (CALD) in men should be performed systematically to avoid preventable morbidity and mortality. While women with ALD do not usually develop cerebral demyelination or adrenal insufficiency, they remain at risk for myeloneuropathy and are no longer considered "carriers." After diagnosis, patients should be connected to the robust support networks, foundations, and research organizations available for ALD/AMN. Core principles of neurologic symptom management parallel those for patients with other etiologies of progressive spastic paraplegia. Appropriate patient candidates for hematopoietic stem cell transplant (HSCT) and other investigational disease-modifying strategies require early identification to achieve optimal outcomes. All patients with ALD/AMN, regardless of sex, age, or symptom severity, benefit from a multidisciplinary approach to longitudinal care spearheaded by the neurologist. This review proposes key strategies for diagnostic confirmation, laboratory and imaging surveillance, approach to symptom management, and guidance for identification of appropriate candidates for HSCT and investigational treatments.

Protective effect of oleic acid against very long-chain fatty acid-induced apoptosis in peroxisome-deficient CHO cells

Very long-chain fatty acids (VLCFAs) are degraded exclusively in peroxisomes, as evidenced by the accumulation of VLCFAs in patients with certain peroxisomal disorders. Although accumulation of VLCFAs is considered to be associated with health issues, including neuronal degeneration, the mechanisms underlying VLCFAs-induced tissue degeneration remain unclear. Here, we report the toxic effect of VLCFA and protective effect of C18: 1 FA in peroxisome-deficient CHO cells. We examined the cytotoxicity of saturated and monounsaturated VLCFAs with chain-length at C20-C26, and found that longer and saturated VLCFA showed potent cytotoxicity at lower accumulation levels. Furthermore, the extent of VLCFA-induced toxicity was found to be associated with a decrease in cellular C18:1 FA levels. Notably, supplementation with C18:1 FA effectively rescued the cells from VLCFA-induced apoptosis without reducing the cellular VLCFAs levels, implying that peroxisome-deficient cells can survive in the presence of accumulated VLCFA, as long as the cells keep sufficient levels of cellular C18:1 FA. These results suggest a therapeutic potential of C18:1 FA in peroxisome disease and may provide new insights into the pharmacological effect of Lorenzo's oil, a 4:1 mixture of C18:1 and C22:1 FA.

Fatty Acid Metabolism in Peroxisomes and Related Disorders

One of the functions of peroxisomes is the oxidation of fatty acids (FAs). The importance of this function in our lives is evidenced by the presence of peroxisomal disorders caused by the genetic deletion of proteins involved in these processes. Unlike mitochondrial oxidation, peroxisomal oxidation is not directly linked to ATP production. What is the role of FA oxidation in peroxisomes? Recent studies have revealed that peroxisomes supply the building blocks for lipid synthesis in the endoplasmic reticulum and facilitate intracellular carbon recycling for membrane quality control. Accumulation of very long-chain fatty acids (VLCFAs), which are peroxisomal substrates, is a diagnostic marker in many types of peroxisomal disorders. However, the relationship between VLCFA accumulation and various symptoms of these disorders remains unclear. Recently, we developed a method for solubilizing VLCFAs in aqueous media and found that VLCFA toxicity could be mitigated by oleic acid replenishment. In this chapter, we present the physiological role of peroxisomal FA oxidation and the knowledge obtained from VLCFA-accumulating peroxisome-deficient cells.

Multivariate analysis and model building for classifying patients in the peroxisomal disorders X-linked adrenoleukodystrophy and Zellweger syndrome in Chinese pediatric patients

BACKGROUND

The peroxisome is a ubiquitous single membrane-enclosed organelle with an important metabolic role. Peroxisomal disorders represent a class of medical conditions caused by deficiencies in peroxisome function and are segmented into enzyme-and-transporter defects (defects in single peroxisomal proteins) and peroxisome biogenesis disorders (defects in the peroxin proteins, critical for normal peroxisome assembly and biogenesis). In this study, we employed multivariate supervised and non-supervised statistical methods and utilized mass spectrometry data of neurological patients, peroxisomal disorder patients (X-linked adrenoleukodystrophy and Zellweger syndrome), and healthy controls to analyze the role of common metabolites in peroxisomal disorders, to develop and refine a classification models of X-linked adrenoleukodystrophy and Zellweger syndrome, and to explore analytes with utility in rapid screening and diagnostics.

RESULTS

T-SNE, PCA, and (sparse) PLS-DA, operated on mass spectrometry data of patients and healthy controls were utilized in this study. The performance of exploratory PLS-DA models was assessed to determine a suitable number of latent components and variables to retain for sparse PLS-DA models. Reduced-features (sparse) PLS-DA models achieved excellent classification performance of X-linked adrenoleukodystrophy and Zellweger syndrome patients.

CONCLUSIONS

Our study demonstrated metabolic differences between healthy controls, neurological patients, and peroxisomal disorder (X-linked adrenoleukodystrophy and Zellweger syndrome) patients, refined classification models and showed the potential utility of hexacosanoylcarnitine (C26:0-carnitine) as a screening analyte for Chinese patients in the context of a multivariate discriminant model predictive of peroxisomal disorders.

An update on the diagnosis and treatment of adrenoleukodystrophy

PURPOSE OF REVIEW

The present review summarizes recent advances in the diagnosis and management of patients with X-linked adrenoleukodystrophy (ALD).

RECENT FINDINGS

Although ALD screening has been on the list of Recommended Uniform Screening Panel since 2016, only 30 states in the United States are currently testing their newborns for this disease. Hematopoietic stem cell transplant (HSCT) remains the only successful treatment option available for early cerebral ALD but does not reverse neurological changes or affect the course of adrenal insufficiency. There remains a significant knowledge gap in our understanding and treatment of this disease. Novel therapies such as gene therapy and gene editing have shown promising results in animal models and are exciting potential treatment options for the future.Recently, the American Academy of Neurologists released their consensus guidelines on the diagnosis, surveillance, and management of ALD.

SUMMARY

Early diagnosis and HSCT are key to improving the morbidity and mortality associated with ALD. The implementation of universal newborn screening for ALD and rigorous investigations of novel diagnostic and therapeutic agents is the need of the hour.

International Recommendations for the Diagnosis and Management of Patients With Adrenoleukodystrophy: A Consensus-Based Approach

Pathogenic variants in the ABCD1 gene cause adrenoleukodystrophy (ALD), a progressive metabolic disorder characterized by 3 core clinical syndromes: a slowly progressive myeloneuropathy, a rapidly progressive inflammatory leukodystrophy (cerebral ALD), and primary adrenal insufficiency. These syndromes are not present in all individuals and are not related to genotype. Cerebral ALD and adrenal insufficiency require early detection and intervention and warrant clinical surveillance because of variable penetrance and age at onset. Newborn screening has increased the number of presymptomatic individuals under observation, but clinical surveillance protocols vary. We used a consensus-based modified Delphi approach among 28 international ALD experts to develop best-practice recommendations for diagnosis, clinical surveillance, and treatment of patients with ALD. We identified 39 discrete areas of consensus. Regular monitoring to detect the onset of adrenal failure and conversion to cerebral ALD is recommended in all male patients. Hematopoietic cell transplant (HCT) is the treatment of choice for cerebral ALD. This guideline addresses a clinical need in the ALD community worldwide as the number of overall diagnoses and presymptomatic individuals is increasing because of newborn screening and greater availability of next-generation sequencing. The poor ability to predict the disease course informs current monitoring intervals but remains subject to change as more data emerge. This knowledge gap should direct future research and illustrates once again that international collaboration among physicians, researchers, and patients is essential to improving care.

Nervonic Acid Attenuates Accumulation of Very Long-Chain Fatty Acids and is a Potential Therapy for Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is an X-linked inherited peroxisomal disorder due to mutations in the ALD protein and characterized by accumulation of very long-chain fatty acids (VLCFA), specifically hexacosanoic acid (C26:0). This can trigger other pathological processes such as mitochondrial dysfunction, oxidative stress, and inflammation, which if involves the brain tissues can result in a lethal form of the disease called childhood cerebral ALD. With the recent addition of ALD to the Recommended Uniform Screening Panel, there is an increase in the number of individuals who are identified with ALD. However, currently, there is no approved treatment for pre-symptomatic individuals that can arrest or delay symptom development. Here, we report our observations investigating nervonic acid, a monounsaturated fatty acid as a potential therapy for ALD. Using ALD patient-derived fibroblasts, we examined whether nervonic acid can reverse VLCFA accumulation similar to erucic acid, the active ingredient in Lorenzo's oil, a dietary intervention believed to alter disease course. We have shown that nervonic acid can reverse total lipid C26:0 accumulation in a concentration-dependent manner in ALD cell lines. Further, we show that nervonic acid can protect ALD fibroblasts from oxidative insults, presumably by increasing intracellular ATP production. Thus, nervonic acid can be a potential therapeutic for individuals with ALD, which can alter cellular biochemistry and improve its function.

Monitoring for and Management of Endocrine Dysfunction in Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a peroxisomal disorder affecting the nervous system, adrenal cortical function, and testicular function. Newborn screening for ALD has the potential to identify patients at high risk for life-threatening adrenal crisis and cerebral ALD. The current understanding of the natural history of endocrine dysfunction is limited. Surveillance guidelines for males with ALD were developed to address the unpredictable nature of evolving adrenal insufficiency. Early recognition and management of adrenal insufficiency can prevent adrenal crisis. While testicular dysfunction in ALD is described, the natural history and complications of low testosterone, as well as the management, are not well described.

The Key Role of Peroxisomes in Follicular Growth, Oocyte Maturation, Ovulation, and Steroid Biosynthesis

The absence of peroxisomes can cause disease in the human reproductive system, including the ovaries. The available peroxisomal gene-knockout female mouse models, which exhibit pathological changes in the ovary and reduced fertility, are listed in this review. Our review article provides the first systematic presentation of peroxisomal regulation and its possible functions in the ovary. Our immunofluorescence results reveal that peroxisomes are present in all cell types in the ovary; however, peroxisomes exhibit different numerical abundances and strong heterogeneity in their protein composition among distinct ovarian cell types. The peroxisomal compartment is strongly altered during follicular development and during oocyte maturation, which suggests that peroxisomes play protective roles in oocytes against oxidative stress and lipotoxicity during ovulation and in the survival of oocytes before conception. In addition, the peroxisomal compartment is involved in steroid synthesis, and peroxisomal dysfunction leads to disorder in the sexual hormone production process. However, an understanding of the cellular and molecular mechanisms underlying these physiological and pathological processes is lacking. To date, no effective treatment for peroxisome-related disease has been developed, and only supportive methods are available. Thus, further investigation is needed to resolve peroxisome deficiency in the ovary and eventually promote female fertility.

Peroxisomal Stress Response and Inter-Organelle Communication in Cellular Homeostasis and Aging

Peroxisomes are key regulators of cellular and metabolic homeostasis. These organelles play important roles in redox metabolism, the oxidation of very-long-chain fatty acids (VLCFAs), and the biosynthesis of ether phospholipids. Given the essential role of peroxisomes in cellular homeostasis, peroxisomal dysfunction has been linked to various pathological conditions, tissue functional decline, and aging. In the past few decades, a variety of cellular signaling and metabolic changes have been reported to be associated with defective peroxisomes, suggesting that many cellular processes and functions depend on peroxisomes. Peroxisomes communicate with other subcellular organelles, such as the nucleus, mitochondria, endoplasmic reticulum (ER), and lysosomes. These inter-organelle communications are highly linked to the key mechanisms by which cells surveil defective peroxisomes and mount adaptive responses to protect them from damages. In this review, we highlight the major cellular changes that accompany peroxisomal dysfunction and peroxisomal inter-organelle communication through membrane contact sites, metabolic signaling, and retrograde signaling. We also discuss the age-related decline of peroxisomal protein import and its role in animal aging and age-related diseases. Unlike other organelle stress response pathways, such as the unfolded protein response (UPR) in the ER and mitochondria, the cellular signaling pathways that mediate stress responses to malfunctioning peroxisomes have not been systematically studied and investigated. Here, we coin these signaling pathways as "peroxisomal stress response pathways". Understanding peroxisomal stress response pathways and how peroxisomes communicate with other organelles are important and emerging areas of peroxisome research.

Increased VLCFA-lipids and ELOVL4 underlie neurodegeneration in frontotemporal dementia

Rare, yet biologically critical, lipids that contain very long chain fatty acids (VLCFA-lipids) are synthesized in the brain by the enzyme ELOVL4. High levels of VLCFA-lipids are toxic to cells and excess VLCFA-lipids are actively removed by ABCD1 in an ATP-dependent manner. Virtually nothing is known about the impact of VLCFA-lipids in neurodegenerative diseases. Here, we investigated the possible role of VLCFA-lipids in frontotemporal dementia (FTD), which is a leading cause of younger-onset dementia. Using quantitative discovery lipidomics, we identified three VLCFA-lipid species that were significantly increased in FTD brain compared to controls, with strong correlations with ELOVL4. Increases in ELOVL4 expression correlated with significant decreases in the membrane-bound synaptophysin in FTD brain. Furthermore, increases in ABCD1 expression correlated with increases in VLCFA-lipids. We uncovered a new pathomechanism that is pertinent to understanding the pathogenesis of FTD.

X-linked adrenoleukodystrophy caused by a novel mutation presenting with various phenotypes in a Taiwanese family

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder that primarily affects the white matter of central nervous system and the adrenal cortex. It is caused by mutations in the adenosine triphosphate-binding cassette, subfamily D, member 1 (ABCD1) gene that results in elevated plasma levels of very long chain fatty acids (VLCFAs). The disease is characterized by an unpredictable variation in phenotypic expressions, including childhood cerebral form (CCALD) and adrenomyeloneuropathy (AMN). Genetic analysis is a reliable method for the diagnosis of X-ALD. We reported a 46-year-old male admitted to Department of Neurology, Chang Gung Memorial Hospital with progressive paraparesis and Addison's disease, which was diagnosed when he was around 20-year-old. Plasma levels of VLCFA showed that his C26:0, C24:0/C22:0 and C26:0/C22:0 ratios were significantly elevated. A novel missense mutation (p.Arg163Cys) caused by the nucleotide change c.487C > T in exon 1 was identified in the ABCD1 gene of the proband and his subclinical family members. In this article, we reviewed the mutations that had been reported at the same position with different phenotypes. Given that the nerve conduction study (NCS) of the proband demonstrated a rare finding of demyelinating polyneuropathy with conduction blocks, we also reviewed the findings of NCS in patients with AMN in literature.

Anesthetic management of pediatric patients diagnosed with X-linked adrenoleukodystrophy: A single-center experience

BACKGROUND

X-linked adrenoleukodystrophy is a progressive demyelinating disease that primarily affects males with an incidence of 1:20 000-30 000. The disease has a wide spectrum of phenotypic expression and may include adrenal insufficiency, cerebral X-linked adrenoleukodystrophy and adrenomyeloneuropathy. The condition has implications for the administration of anesthesia and reports of anesthetic management in those patients are limited at this point.

AIM

To review the perioperative care, complications and outcomes of patients diagnosed with X-linked adrenoleukodystrophy at the University of Minnesota Masonic Children's Hospital.

METHOD

After obtaining IRB approval, we performed a retrospective chart review of pediatric patients diagnosed with X-linked adrenoleukodystrophy who underwent either surgery or diagnostic/therapeutic procedures that included anesthesia services between January 2014 and December 2016. Data included demographics, American Society of Anesthesiologists classification, preoperative diagnosis, history of hematopoietic stem cell transplant, anesthetic approaches, airway management, medications used, intra- and postoperative complications, and patient disposition.

RESULTS

We identified 38 patients who had a total of 166 anesthetic encounters. The majority of patients underwent procedures in the sedation unit (75.9%) and received a total intravenous anesthetic with spontaneous ventilation via a natural airway (86.1%). Preoperative adrenal insufficiency was documented in 87.3% of the encounters. Stress-dose steroids were administered in 70.5% of the performed anesthetics. A variety of anesthetic agents were successfully used including sevoflurane, isoflurane, propofol, midazolam, ketamine, and dexmedetomidine. There were few perioperative complications noted (6.6%) and the majority were of low severity. No anesthesia-related mortality was observed.

CONCLUSIONS

With the availability of skilled pediatric anesthesia care, children with X-linked adrenoleukodystrophy can undergo procedures under anesthesia in sedation units and regular operating rooms with low overall anesthesia risk.

Adrenoleukodystrophy in the era of newborn screening

PURPOSE OF REVIEW

Adrenoleukodystrophy (ALD) is a peroxisomal disorder with varying clinical presentations, including adrenal insufficiency, neurologic disease, and testicular dysfunction. The present review is intended to describe the current knowledge of the pathophysiology of ALD and provide an update regarding newborn screening, diagnosis, monitoring, and treatment.

RECENT FINDINGS

New York State initiated newborn screening for ALD on December 30, 2013. Successful ALD newborn screening has led to its addition on other state newborn screens and recommendations for universal screening. Initial incidence reports, based on newborn screening, suggest ALD may be more common than previously described. The Pediatric Endocrine Society has published guidance for monitoring newborn males with ALD and case reports suggest biochemical adrenal insufficiency can be present during early infancy. Allogeneic hematopoietic stem cell transplant and gene therapy have been effective at halting the progression of cerebral ALD.

SUMMARY

Early diagnosis and monitoring for progression of ALD can prevent adrenal crisis and treat the cerebral form of the disease. Initial guidelines for surveillance are likely to evolve as newborn screening not only aids in early detection and therapeutic interventions for ALD, but also expands our knowledge of the natural history of ALD.

X-linked adrenoleukodystrophy: Pathology, pathophysiology, diagnostic testing, newborn screening and therapies

Adrenoleukodystrophy (ALD) is a rare X-linked disease caused by a mutation of the peroxisomal ABCD1 gene. This review summarizes our current understanding of the pathogenic cell- and tissue-specific roles of lipid species in the context of experimental therapeutic strategies and provides an overview of critical historical developments, therapeutic trials and the advent of newborn screening in the USA. In ALD, very long-chain fatty acid (VLCFA) chain length-dependent dysregulation of endoplasmic reticulum stress and mitochondrial radical generating systems inducing cell death pathways has been shown, providing the rationale for therapeutic moiety-specific VLCFA reduction and antioxidant strategies. The continuing increase in newborn screening programs and promising results from ongoing and recent therapeutic investigations provide hope for ALD.

X-linked Adrenoleukodystrophy: Pathology, Pathophysiology, Diagnostic Testing, Newborn Screening, and Therapies

Adrenoleukodystrophy (ALD) is a rare X-linked disease caused by a mutation of the peroxisomal ABCD1 gene. This review summarizes our current understanding of the pathogenic cell- and tissue-specific role of lipid species in the context of experimental therapeutic strategies and provides an overview of critical historical developments, therapeutic trials, and the advent of newborn screening in the United States. In ALD, very long chain fatty acid (VLCFA) chain-length-dependent dysregulation of endoplasmic reticulum stress and mitochondrial radical generating systems inducing cell death pathways has been shown, providing the rationale for therapeutic moiety-specific VLCFA reduction and antioxidant strategies. The continuing increase in newborn screening programs and promising results from ongoing and recent therapeutic investigations provide hope for ALD.

Clinical, neuroimaging, biochemical, and genetic features in six Chinese patients with Adrenomyeloneuropathy

Background

Adrenoleukodystrophy is a rare neurogenetic disease, AMN is the most common adult phenotype, such patients in China have not gotten enough attention. This article aims to study the features of AMN in Chinese patients and expand the gene spectrum of Chinese X-linked adrenoleukodystrophy (X-ALD) patients.

Methods

We applied clinical analysis, radiology, plasma levels of very long chain fatty acids (VLCFA) and genetic analysis to test the 6 Chinese AMN patients.

Results

All 6 patients are men. Ages of neurological symptom onset are distributed between 21 and 38. Sexual dysfunction occurred in 5 of 6 patients. Three patients had positive family history. Five patients had Addison’s disease. Four patients were diagnosed as pure AMN, while the other two patients were with cerebral involvement. Four patients had abnormalities of nerve conduction studies. There were four patients with central conduction defects in somatosensory evoked potential tests. All 6 patients were found diffuse cord atrophy in spinal MRI. Brain MRI showed abnormal signals in 2 of the 6 tested patients, which indicated the clinical phenotypes. Plasma levels of VLCFA, as well as C24:0/C22:0 and C26:0/C22:0 ratios were elevated in 5 tested patients. Five different ABCD1 mutations were identified in 5 tested patients, one of which was a de novo mutation, and the other four have been reported previously.

Conclusion

This research described the clinical, neuroimaging, biochemical, and genetic sides of Chinese AMN patients. A de novo mutation in the ABCD1 gene sequence was identified. Emotional trauma may trigger or aggravate the development of cerebral demyelination in AMN patients. Regular evaluation of brain MRI is important for AMN patients, especially for ‘pure AMN’ patients. When encountering patients with ‘myeloneuropathy-only’, neurologists should not ignore the tests of VLCFA or/and the ABCD1 gene.

Electronic supplementary material

The online version of this article (10.1186/s12883-019-1449-5) contains supplementary material, which is available to authorized users.

Etiology and treatment of adrenoleukodystrophy: new insights from Drosophila

Adrenoleukodystrophy (ALD) is a fatal progressive neurodegenerative disorder affecting brain white matter. The most common form of ALD is X-linked (X-ALD) and results from mutation of the ABCD1-encoded very-long-chain fatty acid (VLCFA) transporter. X-ALD is clinically heterogeneous, with the cerebral form being the most severe. Diagnosed in boys usually between the ages of 4 and 8 years, cerebral X-ALD symptoms progress rapidly (in as little as 2 years) through declines in cognition, learning and behavior, to paralysis and ultimately to a vegetative state and death. Currently, there are no good treatments for X-ALD. Here, we exploit the Drosophila bubblegum (bgm) double bubble (dbb) model of neurometabolic disease to expand diagnostic power and therapeutic potential for ALD. We show that loss of the Drosophila long-/very-long-chain acyl-CoA synthetase genes bgm and/or dbb is indistinguishable from loss of the Drosophila ABC transporter gene ABCD Shared loss-of-function phenotypes for synthetase and transporter mutants point to a lipid metabolic pathway association with ALD-like neurodegenerative disease in Drosophila; a pathway association that has yet to be established in humans. We also show that manipulation of environment increases the severity of neurodegeneration in bgm and dbb mutant flies, adding even further to a suite of new candidate ALD disease-causing genes and pathways in humans. Finally, we show that it is a lack of lipid metabolic pathway product and not (as commonly thought) an accumulation of pathway precursor that is causative of neurometabolic disease: addition of medium-chain fatty acids to the diet of bgm or dbb mutant flies prevents the onset of neurodegeneration. Taken together, our data provide new foundations both for diagnosing ALD and for designing effective, mechanism-based treatment protocols.This article has an associated First Person interview with the first author of the paper.

Modeling and rescue of defective blood-brain barrier function of induced brain microvascular endothelial cells from childhood cerebral adrenoleukodystrophy patients

Background

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene. 40% of X-ALD patients will convert to the deadly childhood cerebral form (ccALD) characterized by increased permeability of the brain endothelium that constitutes the blood–brain barrier (BBB). Mutation information and molecular markers investigated to date are not predictive of conversion. Prior reports have focused on toxic metabolic byproducts and reactive oxygen species as instigators of cerebral inflammation and subsequent immune cell invasion leading to BBB breakdown. This study focuses on the BBB itself and evaluates differences in brain endothelium integrity using cells from ccALD patients and wild-type (WT) controls.

Methods

The blood–brain barrier of ccALD patients and WT controls was modeled using directed differentiation of induced pluripotent stem cells (iPSCs) into induced brain microvascular endothelial cells (iBMECs). Immunocytochemistry and PCR confirmed characteristic expression of brain microvascular endothelial cell (BMEC) markers. Barrier properties of iBMECs were measured via trans-endothelial electrical resistance (TEER), sodium fluorescein permeability, and frayed junction analysis. Electron microscopy and RNA-seq were used to further characterize disease-specific differences. Oil-Red-O staining was used to quantify differences in lipid accumulation. To evaluate whether treatment with block copolymers of poly(ethylene oxide) and poly(propylene oxide) (PEO–PPO) could mitigate defective properties, ccALD-iBMECs were treated with PEO–PPO block copolymers and their barrier properties and lipid accumulation levels were quantified.

Results

iBMECs from patients with ccALD had significantly decreased TEER (2592 ± 110 Ω cm²) compared to WT controls (5001 ± 172 Ω cm²). They also accumulated lipid droplets to a greater extent than WT-iBMECs. Upon treatment with a PEO–PPO diblock copolymer during the differentiation process, an increase in TEER and a reduction in lipid accumulation were observed for the polymer treated ccALD-iBMECs compared to untreated controls.

Conclusions

The finding that BBB integrity is decreased in ccALD and can be rescued with block copolymers opens the door for the discovery of BBB-specific molecular markers that can indicate the onset of ccALD and has therapeutic implications for preventing the conversion to ccALD.

Electronic supplementary material

The online version of this article (10.1186/s12987-018-0094-5) contains supplementary material, which is available to authorized users.

A zebrafish model of X-linked adrenoleukodystrophy recapitulates key disease features and demonstrates a developmental requirement for abcd1 in oligodendrocyte patterning and myelination

X-linked adrenoleukodystrophy (ALD) is a devastating inherited neurodegenerative disease caused by defects in the ABCD1 gene and affecting peripheral and central nervous system myelin. ABCD1 encodes a peroxisomal transmembrane protein required for very long chain fatty acid (VLCFA) metabolism. We show that zebrafish (Danio rerio) Abcd1 is highly conserved at the amino acid level with human ABCD1, and during development is expressed in homologous regions including the central nervous system and adrenal glands. We used TALENs to generate five zebrafish abcd1 mutant allele lines introducing premature stop codons in exon 1, as well as obtained an abcd1 allele from the Zebrafish Mutation Project carrying a point mutation in a splice donor site. Similar to patients with ALD, zebrafish abcd1 mutants have elevated VLCFA levels. Interestingly, we found that CNS development of the abcd1 mutants is disrupted, with hypomyelination in the spinal cord, abnormal patterning and decreased numbers of oligodendrocytes, and increased cell death. By day of life five abcd1 mutants demonstrate impaired motor function, and overall survival to adulthood of heterozygous and homozygous mutants is decreased. Expression of human ABCD1 in oligodendrocytes rescued apoptosis in the abcd1 mutant. In summary, we have established a zebrafish model of ALD that recapitulates key features of human disease pathology and which reveals novel features of underlying disease pathogenesis.

Adrenoleukodystrophy - neuroendocrine pathogenesis and redefinition of natural history

X-Linked adrenoleukodystrophy (ALD) is a peroxisomal metabolic disorder with a highly complex clinical presentation. ALD is caused by mutations in the ABCD1 gene, which leads to the accumulation of very long-chain fatty acids in plasma and tissues. Virtually all men with ALD develop adrenal insufficiency and myelopathy. Approximately 60% of men develop progressive cerebral white matter lesions (known as cerebral ALD). However, one cannot identify these individuals until the early changes are seen using brain imaging. Women with ALD also develop myelopathy, but generally at a later age than men and adrenal insufficiency or cerebral ALD are very rare. Owing to the multisystem symptomatology of the disease, patients can be assessed by the paediatrician, general practitioner, endocrinologist or a neurologist. This Review describes current knowledge on the clinical presentation, diagnosis and treatment of ALD, and highlights gaps in our knowledge of the natural history of the disease owing to an absence of large-scale prospective cohort studies. Such studies are necessary for the identification of new prognostic biomarkers to improve care for patients with ALD, which is particularly relevant now that newborn screening for ALD is being introduced.

A hierarchical Bayesian approach for combining pharmacokinetic/pharmacodynamic modeling and Phase IIa trial design in orphan drugs: Treating adrenoleukodystrophy with Lorenzo's oil

X-linked adrenoleukodystrophy (X-ALD) is a rare, progressive, and typically fatal neurodegenerative disease. Lorenzo's oil (LO) is one of the few X-ALD treatments available, but little has been done to establish its clinical efficacy or indications for its use. In this article, we analyze data on 116 male asymptomatic pediatric patients who were administered LO. We offer a hierarchical Bayesian statistical approach to understand LO pharmacokinetics (PK) and pharmacodynamics (PD) resulting from an accumulation of very long-chain fatty acids. We experiment with individual- and observational-level errors and various choices of prior distributions and deal with the limitation of having just one observation per administration of the drug, as opposed to the more usual multiple observations per administration. We link LO dose to the plasma erucic acid concentrations by PK modeling, and then link this concentration to a biomarker (C26, a very long-chain fatty acid) by PD modeling. Next, we design a Bayesian Phase IIa study to estimate precisely what improvements in the biomarker can arise from various LO doses while simultaneously modeling a binary toxicity endpoint. Our Bayesian adaptive algorithm emerges as reasonably robust and efficient while still retaining good classical (frequentist) operating characteristics. Future work looks toward using the results of this trial to design a Phase III study linking LO dose to actual improvements in health status, as measured by the appearance of brain lesions observed via magnetic resonance imaging.

Endocrine Dysfunction in X-Linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene and leads to an elevation of very-long-chain fatty acids (VLCFA). The accumulation of the VLCFA and the associated oxidative stress can present with a spectrum of significant neurologic disease, adrenal insufficiency, and testicular dysfunction in males with ABCD1 gene mutations. Much of the published literature for X-ALD has focused on the associated devastating progressive neurologic conditions. The purpose of this review is to summarize the concerns for endocrine dysfunction associated with X-ALD and provide guidance for monitoring and management of adrenal insufficiency.

Zellweger spectrum disorders: clinical overview and management approach

Zellweger spectrum disorders (ZSDs) represent the major subgroup within the peroxisomal biogenesis disorders caused by defects in PEX genes. The Zellweger spectrum is a clinical and biochemical continuum which can roughly be divided into three clinical phenotypes. Patients can present in the neonatal period with severe symptoms or later in life during adolescence or adulthood with only minor features. A defect of functional peroxisomes results in several metabolic abnormalities, which in most cases can be detected in blood and urine. There is currently no curative therapy, but supportive care is available. This review focuses on the management of patients with a ZSD and provides recommendations for supportive therapeutic options for all those involved in the care for ZSD patients.

Hematopoietic cell transplantation does not prevent myelopathy in X-linked adrenoleukodystrophy: a retrospective study

BACKGROUND

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal metabolic disorder. Male patients develop adrenocortical insufficiency (80 % before 18 years), a chronic myelopathy (adrenomyeloneuropathy (AMN); all in adulthood), or progressive cerebral demyelination (cerebral ALD; 40 % before 18 years). Cerebral ALD is treated with haematopoetic cell transplantation (HCT). It is unknown if AMN still develops in patients with X-ALD that underwent HCT for cerebral ALD in childhood.

PATIENTS AND METHODS

A retrospective observational study was performed by selecting all adult patients with X-ALD in our cohort that underwent HCT in childhood.

RESULTS

This retrospective study found that three out of five patients in our cohort who underwent HCT in childhood developed signs of myelopathy in adulthood.

CONCLUSION

These data suggest that HCT for cerebral ALD in childhood does not prevent the onset of AMN in X-ALD in adulthood.

X-linked adrenoleukodystrophy: are signs of hypogonadism always due to testicular failure?

We present the clinical and hormonal findings of a young male with X-linked adrenoleukodystrophy (X-ALD), with special emphasis on the biochemical and clinical pattern of hypogonadism. A patient, with primary adrenal insufficiency since the age of 5 years, developed progressive neurological symptoms at the age of 29. Diagnosis of X-ALD was established by elevated serum very long chain fatty acids (VLCFAs) and genetic testing. His sexual body hair was sparse. Hormonal investigations revealed normal testosterone and inappropriately elevated LH levels. Androgen receptor gene analysis was negative for mutations or polymorphic variants associated with decreased receptor activity. Signs of hypogonadism in patients with confirmed X-ALD are not exclusively due to primary testicular failure. Tissue specific androgen resistance represents an alternative possibility. Since no loss-of-function mutations were detected in the androgen receptor, it is speculated that the patient's androgen resistance could be part of a functional defect mediated through VLCFA accumulation at the testosterone receptor and/or post-receptor levels.

Neurologic complications of disorders of the adrenal glands

Disorders of the adrenal glands frequently have secondary neurological manifestations, while some diseases that involve the central nervous system are accompanied by adrenal gland dysfunction. Excessive corticosteroid secretions in primary or secondary Cushing's syndrome causes muscle weakness and behavioral disturbances, such as emotional lability and sometimes depression, while adrenal insufficiency may cause fatigue, weakness, and depression. Adrenoleukodystrophy and adrenoneuromyelopathy are X-linked recessive disorders of the metabolism of very long chain fatty acids that manifest with white matter abnormalities of the brain, myelopathy and/or neuropathy, as well as adrenal insufficiency. Other disorders of the adrenal glands include hyperaldosteroidism, which may cause weakness from hypokalemia. Dysfunction of the adrenal medulla causes excessive or deficient secretion of catecholamines, primarily causing cardiovascular symptoms. This chapter reviews the clinical manifestations and diagnostic aspects and treatment of the various disorders of the adrenal glands. Some of the congenital adrenal diseases are also discussed.

Myelin peroxisomes - essential organelles for the maintenance of white matter in the nervous system

Peroxisomes are cellular compartments primarily associated with lipid metabolism. Most cell types, including nervous system cells, harbor several hundred of these organelles. The importance of peroxisomes for central nervous system white matter is evidenced by a variety of human peroxisomal disorders with neurological impairment frequently involving the white matter. Moreover, the most frequent childhood white matter disease, X-linked adrenoleukodystrophy, is a peroxisomal disorder. During the past decade advances in imaging techniques have enabled the identification of peroxisomes within the myelin sheath, especially close to nodes of Ranvier. Although the function of myelin peroxisomes is not solved yet on molecular level, recently acquired knowledge suggests a central role for these organelles in axo-glial metabolism. This review focuses on the biology of myelin peroxisomes as well as on the pathology of myelin and myelinated axons that is observed as a consequence of partial or complete peroxisomal dysfunction in the brain.

Bezafibrate lowers very long-chain fatty acids in X-linked adrenoleukodystrophy fibroblasts by inhibiting fatty acid elongation

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene encoding ALDP, an ATP-binding-cassette (ABC) transporter located in the peroxisomal membrane. ALDP deficiency results in impaired peroxisomal β-oxidation and the subsequent accumulation of very long-chain fatty acids (VLCFA; > C22:0) in plasma and tissues. VLCFA are primarily derived from endogenous synthesis by ELOVL1. Therefore inhibiting this enzyme might constitute a feasible therapeutic approach. In this paper we demonstrate that bezafibrate, a PPAR pan agonist used for the treatment of patients with hyperlipidaemia reduces VLCFA levels in X-ALD fibroblasts. Surprisingly, the VLCFA-lowering effect was independent of PPAR activation and not caused by the increase in either mitochondrial or peroxisomal fatty acid β-oxidation capacity. In fact, our results show that bezafibrate reduces VLCFA synthesis by decreasing the synthesis of C26:0 through a direct inhibition of fatty acid elongation activity. Taken together, our data indicate bezafibrate as a potential pharmacotherapeutic treatment for X-ALD. A clinical trial is currently ongoing to evaluate the effect in patients with X-ALD.

Advances and pitfalls of cell therapy in metabolic leukodystrophies

Leukodystrophies are a group of disorders characterized by myelin dysfunction, either at the level of myelin formation or maintenance, that affect the central nervous system (CNS) and also in some cases, to a lesser extent, the peripheral nervous system (PNS). Although these genetic-based disorders are generally rare, all together they have a significant impact in the society, with an estimated overall incidence of 1 in 7,663 live births. Currently, there is no cure for leukodystrophies, and the development of effective treatments remains challenging. Not only leukodystrophies generally progress very fast, but also most are multifocal needing the simultaneous targeting at multiple sites. Moreover, as the CNS is affected, the blood-brain barrier (BBB) limits the efficacy of treatment. Recently, interest on cell therapy has increased, and the leukodystrophies for which metabolic correction is needed have become first-choice candidates for cell-based clinical trials. In this review, we present and discuss the available cell transplantation therapies in metabolic leukodystrophies including fucosidosis, X-linked adrenoleukodystrophy, metachromatic leukodystrophy, Canavan disease, and Krabbe's disease. We will discuss the latest advances of cell therapy and its pitfalls in this group of disorders, taking into account, among others, the limitations imposed by reduced cell migration in multifocal conditions, the need to achieve corrective enzyme threshold levels, and the growing awareness that not only myelin but also the associated axonopathy needs to be targeted in some leukodystrophies.

X-linked adrenoleukodystrophy (X-ALD): clinical presentation and guidelines for diagnosis, follow-up and management

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder. The disease is caused by mutations in the ABCD1 gene that encodes the peroxisomal membrane protein ALDP which is involved in the transmembrane transport of very long-chain fatty acids (VLCFA; ≥C22). A defect in ALDP results in elevated levels of VLCFA in plasma and tissues. The clinical spectrum in males with X-ALD ranges from isolated adrenocortical insufficiency and slowly progressive myelopathy to devastating cerebral demyelination. The majority of heterozygous females will develop symptoms by the age of 60 years. In individual patients the disease course remains unpredictable. This review focuses on the diagnosis and management of patients with X-ALD and provides a guideline for clinicians that encounter patients with this highly complex disorder.

Reproductive function in men affected by X-linked adrenoleukodystrophy/adrenomyeloneuropathy

BACKGROUND

X-linked adrenoleukodystrophy (X-ALD) is the most frequent, severely neurodegenerative, clinically heterogeneous peroxisomal disorder, the signs of which are a consequence of myelin, adrenal cortex, and testes impairment.

OBJECTIVE

We studied testosterone, LH, and FSH levels in X-ALD/adrenomyeloneuropathy (AMN) patients. We evaluate the ability to procreate of these patients by analysis of pedigree and family screening by detection of very long-chain fatty acid (VLCFA) levels.

SUBJECT AND METHODS

Seventeen patients with X-ALD/AMN (16 with AMN and one asymptomatic) aged 24-48 (mean±S.D., 34.7±5.9) years, were identified based on the clinical picture, magnetic resonance imaging, and the presence of increased serum VLCFA levels. Nine X-ALD/AMN patients' daughters, mean ages ±S.D.=7.7±3.8 years, were identified as heterozygote by elevated VLCFA levels. Serum VLCFA levels were determined as ester derivatives by a gas chromatography method. Serum testosterone, LH, and FSH levels in X-ALD/AMN patients were detected by IRMAs.

RESULTS

Serum testosterone levels were at the lowest levels of normal range but serum LH and FSH concentrations were increased in 57.1 and in 42.9% of X-ALD/AMN patients respectively. Among the 11 investigated of X-ALD/AMN married adult men, nine had produced offspring, a total of 13 children. All patients' daughters showed elevated serum VLCFA at heterozygote levels.

CONCLUSION

In this study, we report that in a group of X-ALD/AMN married adult men, we did not find a significant decrease in fertility compared with the Polish population (18.2 vs 15%).

Adrenoleukodystrophy in female heterozygotes: underrecognized and undertreated

X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disease resulting from mutations in the gene ABCD1 and alterations in peroxisomal beta-oxidation of long chain fatty acids. As it has been frequently discussed, it manifests a wide range of phenotypes in male, with progressive myelopathy being the most common. Even though the gene is localized to the X-chromosome and a region subject to X-inactivation, female carriers still are affected significantly by this condition. It has been stated that between 20 and 50% of women who are carriers may manifest some symptoms and recent evidence has suggested the differences in disease manifestations and relative rates of progression between men and women. However there have been only limited studies specifically addressing this and to date there has been no comprehensive review discussing the different phenotypes in female carriers, as well as the differences in disease onset, progression, disability, nervous system pathology and neuroimaging patterns compared to affected males. This is of key importance as similarities and differences between genders will assist in determining how best to target therapies in all affected individuals as opportunities for treatment present themselves. As will be further addressed in this review, we need to improve our understanding of the associations of emergent neuroimaging techniques to physical disability in this population. We reviewed the clinical presentations in the carrier population, the distinct disability profile and neuroimaging findings in order to put together pieces of this neglected segment in X-ALD and give direction to further studies.

Treatment of an adrenomyeloneuropathy patient with Lorenzo's oil and supplementation with docosahexaenoic acid--a case report

This is a case report of adrenomyeloneuropathy (AMN), the adult variant of adrenoleukodystryphy (ALD). The diagnoses in the patient, aged 34, was confirmed via increased serum very long chain fatty acid concentration (VLCFA). Treatment started with the cholesterol lowering drug, atorvastatin, followed by add-on therapy with Lorenzo's oil (LO) and finally supplementation with docosahexaenoic acid (DHA). The magnetic resonance imaging (MRI) scan of the AMN patient before DHA treatment, already showed abnormal white matter in the brain. Although the MRI showed no neurological improvement after 6 months of DHA treatment, no selective progression of demyelination was detected in the AMN patient. Contrary to what was expected, LO failed to sustain or normalize the VLCFA levels or improve clinical symptoms. It was however, shown that DHA supplementation in addition to LO, increased DHA levels in both plasma and red blood cells (RBC). Additionally, the study showed evidence that the elongase activity in the elongation of eicosapentaenoic acid (EPA) to docosapentaenoic acid (DPA) might have been significantly compromised, due to the increased DHA levels.

Fatty acid omega-oxidation as a rescue pathway for fatty acid oxidation disorders in humans

Fatty acids (FAs) can be degraded via different mechanisms including α-, β- and ω-oxidation. In humans, a range of different genetic diseases has been identified in which either mitochondrial FA β-oxidation, peroxisomal FA β-oxidation or FA α-oxidation is impaired. Treatment options for most of these disorders are limited. This has prompted us to study FA ω-oxidation as a rescue pathway for these disorders, based on the notion that if the ω-oxidation of specific FAs could be upregulated one could reduce the accumulation of these FAs and the subsequent detrimental effects in the different groups of disorders. In this minireview, we describe our current state of knowledge in this area with special emphasis on Refsum disease and X-linked adrenoleukodystrophy.

Biochemical aspects of X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder. The disease is characterized by the accumulation of very long-chain fatty acids (VLCFA; >C22) in plasma and tissues. X-ALD is caused by mutations in the ABCD1 gene encoding ALDP, an adenosine triphosphate (ATP)-binding-cassette (ABC) transporter located in the peroxisomal membrane. In this paper, we describe the current knowledge on the function of ALDP, its role in peroxisomal VLCFA beta-oxidation and the consequences of a defect in ALDP on VLCFA metabolism. Furthermore, we pay special attention to the role of the VLCFA elongation system in VLCFA homeostasis, with elongation of very long-chain fatty acids like-1 (ELOVL1) as key player, and its relevance to X-ALD.

Current and future pharmacological treatment strategies in X-linked adrenoleukodystrophy

Mutations in the ABCD1 gene cause the clinical spectrum of the neurometabolic disorder X-linked adrenoleukodystrophy/adrenomyeloneuropathy (X-ALD/AMN). Currently, the most efficient therapeutic opportunity for patients with the cerebral form of X-ALD is hematopoietic stem cell transplantation and possibly gene therapy of autologous hematopoietic stem cells. Both treatments, however, are only accessible to a subset of X-ALD patients, mainly because of the lack of markers that can predict the onset of cerebral demyelination. Moreover, for female or male X-ALD patients with AMN, currently only unsatisfying therapeutic opportunities are available. Thus, this review focuses on current and urgently needed future pharmacological therapies. The treatment of adrenal and gonadal insufficiency is well established, whereas applications of immunomodulatory and immunosuppressive drugs have failed to prevent progression of cerebral neuroinflammation. The use of Lorenzo's oil and the inefficacy of lovastatin to normalize very-long-chain fatty acids in clinical trials as well as currently experimental and therefore possible future therapeutic strategies are reviewed. The latter include pharmacological gene therapy mediated by targeted upregulation of ABCD2, the closest homolog of ABCD1, antioxidative drug treatment, small molecule histone deacetylase inhibitors such as butyrates and valproic acid, and other neuroprotective attempts.

X-linked adrenoleukodystrophy: clinical course and minimal incidence in South Brazil

X-linked adenoleukodystrophy is a genetic disease that affects the degradation of very long-chain fatty acids. In male patients, common pictures are the cerebral form (CALD), myeloneuropathy (AMN), and Addison-only.

OBJECTIVE

To describe the clinical course of affected male patients from South Brazil between 1993 and 2007.

METHODS

Affected male patients and their maternal lineages were studied from a clinical, neurological and biochemical standpoint.

RESULTS

Eighty-three male patients from 30 families were biochemically evaluated: 51 were affected. 27/51 (54%) presented the cerebral form; 11/51 had AMN (22%); 5 had Addison-only (10%), and 8 (16%) were asymptomatic. Between 2002 and 2006, the minimal incidence was 1:35,000 males in our State (South Brazil). Forty-three affected individuals were followed for 5.4+/-3.7 years. Of 10 boys detected at early stages, three developed CALD. These three boys and another five CALD at baseline were referred to hematopoietic stem cell transplantation. Seven transplants were carried out, 5 with good clinical evolution after 2.2 years post-transplant. The non-transplanted case was later defined as a stable cerebral form.

DISCUSSION

Among the present families, the observed cases were comparable to the 50% expected by Mendelian segregation. Based on the natural history, the number of cases that developed CALD was similar to the expected. Transplants were successful in 70% of cases. The occurrence of a stable cerebral form pointed to an urgent need for better markers of active cerebral disease.

Fast diffusion of very long chain saturated fatty acids across a bilayer membrane and their rapid extraction by cyclodextrins: implications for adrenoleukodystrophy

Abnormalities in the transport of saturated very long chain fatty acids (VLCFA; >C18:0) contribute to their toxic levels in peroxisomal disorders of fatty acid metabolism, such as adrenoleukodystrophy and adrenomyeloneuropathy. We previously showed that VLCFA desorb much slower than normal dietary fatty acids from both albumin and protein-free lipid bilayers. The important step of transbilayer movement (flip-flop) was not measured directly as a consequence of this very slow desorption from donors, and the extremely low aqueous solubility of VLCFA precludes addition of unbound VLCFA to lipid membranes. We have overcome these limitations using methyl-beta-cyclodextrin to solubilize VLCFA for rapid delivery to "acceptor" phosphatidylcholine vesicles (small and large unilamellar) and to cells. VLCFA binding was monitored in real time with the fluorescent probe fluorescein-labeled phosphatidylethanolamine in the outer membrane leaflet, and entrapped pyranine was used to detect flip-flop across the membrane. The upper limit of the rate of flip-flop across the membrane was independent of temperature and media viscosity and was similar for model raft and non-raft membranes as well as living cells. We further showed that cyclodextrins can extract VLCFA rapidly (within seconds) from vesicles and cells, which have implications for the mechanism and potential alternative approaches to treat adrenoleukodystrophy. Because VLCFA diffuse through the lipid bilayer, proteins may not be required for their transport across the peroxisomal membrane.

The X-Linked Adrenoleukodystrophy (X-ALD) and Oxidative Stress

Most of the studies indicate that there is as yet no complete cure for X-ALD. However, methods of the treatment seem to slow rather than treat the disease. One method is the use of Lorenzo's oil in conjunction with a low fat diet, which may help in cerebral X-ALD. X-ALD is in very close resemblance to another neurodegenerative disease, amyotrophic lateral sclerosis (ALS). One of the believed pathomechanisms of ALS is oxidative stress; therefore, this article's emphasis on the role of reactive oxygen species in X-ALD. The aim of the present study was to review the literature concerning the advances in the treatment of X-adrenoleukodystrophy (X-ALD, OMIM # 300100) in the last two decades and to shed more light on the link between oxidative stress and X-ALD. This review article may point to a deficit in reactive oxygen species (ROS) scavenging and/or ROS overproduction being involved in the aetiopathology of these neurodegenerative diseases. Consequently, one of the useful neuronal rescue strategies could be the treatment with antioxidant agents.

[Primary adrenal insufficiency as the form of onset of adrenoleukodystrophy in a 4-year-old boy]

X-linked adrenoleukodystrophy is an inherited metabolic disease caused by the accumulation of saturated very long chain fatty acids (VLCFA). Given that the form of presentation can be primary adrenal insufficiency, diagnosis in affected males is important. Patient was a 4-year-old boy with attention deficit hyperactivity disorder, cutaneous-mucosal hyperpigmentation, and dehydration with hyponatremia and hyperpotassemia was diagnosed with adrenoleukodystrophy presenting as primary adrenal insufficiency. Antiadrenal antibodies: negative. Plasma VLCFA: C(26:0)=1.25mg/ml (0.18-0.48), C(24:0)/C(22:0) =1.53 (< 1), and C(26:0)/ C(22:0)=0.04 (< 0.02). Abdominal computed tomography: small adrenal glands. Cranial magnetic resonance imaging and evoked potentials: normal at diagnosis and with signs of white matter demyelination after 2 years of follow-up. Testing for an autoimmune etiology and adrenoleukodystrophy is important in boys with primary adrenal insufficiency before Addison's disease is diagnosed.

Therapy of X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD; OMIM #300100) is caused by defects of the ABCD1 gene on chromosome Xq28, resulting in an impairment of peroxisomal beta-oxidation and the accumulation of saturated very long chain fatty acids (VLCFAs). Primary manifestations occur in the CNS, the adrenal cortex and the testes' Leydig cells. The clinical presentation shows a marked variability which is not explained by the different X-ALD genotypes. Phenotypes range from rapidly progressive cerebral disease with childhood (childhood cerebral ALD [CCALD]) or adulthood (adult cerebral ALD [ACALD]) onset leading to death within a few years, over adult-onset adrenomyeloneuropathy (AMN) with or without focal CNS demyelination, AMN converting into a rapidly progressive, cerebral demyelinating phenotype resembling CCALD, to slow disease progression over decades, or adrenal insufficiency only. Approximately 50% of female heterozygotes develop moderate spastic paresis resembling the AMN phenotype. This review focuses on current experiences with different therapeutic approaches. Lorenzo's oil did not prove to be effective in cerebral inflammatory disease variants, but asymptomatic patients, and speculatively AMN variants without cerebral involvement, as well as female carriers may benefit from early intake of oleic and erucic acids in addition to VLCFA restriction. Hormone-replacement therapy is necessary in all patients with adrenal insufficiency. Hematopoietic stem cell transplantation has been reported to be effective in presymptomatic or early symptomatic CCALD, and may well also be a final therapeutic option in early ACALD patients. Early detection of mutation carriers and timely initiation of therapy is important for the effectiveness of all therapeutic efforts. Gene therapy of endogenous hematopoietic stem cells, pharmacological upregulation of other genes encoding proteins involved in peroxisomal beta-oxidation, reduction of oxidative stress, and possibly lovastatin are candidates for future X-ALD therapies.

Seven-Tesla proton magnetic resonance spectroscopic imaging in adult X-linked adrenoleukodystrophy

BACKGROUND

Adults with X-linked adrenoleukodystrophy (X-ALD) remain at risk for progressive neurological deterioration. Phenotypes vary in their pathology, ranging from axonal degeneration to inflammatory demyelination. The severity of symptoms is poorly explained by conventional imaging.

OBJECTIVE

To test the hypothesis that neurochemistry in normal-appearing brains differs in adult phenotypes of X-ALD and that neurochemical changes correlate with the severity of symptoms.

PATIENTS AND METHODS

Using a 7-Tesla scanner, we performed structural and proton magnetic resonance spectroscopic imaging in 13 adult patients with X-ALD: 4 patients with adult cerebral ALD, 5 patients with adrenomyeloneuropathy (AMN), and 4 female heterozygotes. Nine healthy controls were included.

RESULTS

Among adult X-ALD phenotypes, the myo-inositol to creatine ratio was 46% higher and the choline to creatine ratio was 21% higher in normal-appearing white matter of those with adult cerebral ALD compared with those with AMN (P < .05). Both N-acetylaspartate to creatine (P = .03) and glutamate to creatine (P = .04) ratios were lower in AMN patients than in controls. There were no significant differences between patients with AMN and female heterozygotes. In the cortex, patients with adult cerebral ALD had lower N-acetylaspartate to creatine ratios compared with female heterozygotes and controls (P = .02). The global myo-inositol to creatine ratio demonstrated a significant association with Expanded Disability Status Scale score (Spearman rho = 0.66, P = .04).

CONCLUSIONS

Seven-Tesla proton magnetic resonance spectroscopic imaging reveals differences in the neurochemistry of adult cerebral ALD but cannot distinguish AMN patients from female heterozygotes. Myo-inositol to creatine ratio correlates with the severity of the symptoms and may be a meaningful biomarker in adult X-ALD.

Hexacosanoic and docosanoic acids plasma levels in patients with cerebral childhood and asymptomatic X-linked adrenoleukodystrophy: Lorenzo's oil effect

X-linked adrenoleukodystrophy (X-ALD) is an inherited disorder of peroxisomal metabolism, biochemically characterized by deficient beta-oxidation of saturated very long chain fatty acids (VLCFA). The consequent accumulation of these fatty acids in different tissues and in biological fluids is associated with a progressive central and peripheral demyelination, as well as with adrenocortical insufficiency and hypogonadism. Seven variants of this disease have been described, cerebral childhood being the most frequent. The recommended therapy consists of the use of the glyceroltrioleate/glyceroltrierucate mixture known as Lorenzo's Oil (LO), combined with a VLCFA-poor diet, but only in asymptomatic patients will this treatment prevent the progression of the symptomatology. In the present study we evaluated the biochemical course of patients with cerebral childhood (CCER) and asymptomatic clinical forms of X-ALD treated with LO associated with a VLCFA-restricted diet. We observed that hexacosanoic acid plasma concentrations and hexacosanoic/docosanoic ratio were significantly reduced in CCER patients during treatment when compared with diagnosis. Hexacosanoic acid plasma level was significantly reduced when compared with that at diagnosis and achieved the normal levels only in asymptomatic patients under LO treatment. In asymptomatic patients the magnitude of hexacosanoic acid decrease was higher than that of the CCER patients. These results show the good biochemical response of LO treatment in asymptomatic X-ALD patients. It is possible to suppose that this could be correlated with the prevention of the appearance of neurological signals in this group of patients treated with LO.

“Lorenzo’s Oil” Therapy for X-linked Adrenoleukodystrophy: Rationale and Current Assessment of Efficacy

X-linked adrenoleukodystrophy (X-ALD) is a genetic disorder that damages the nervous system and is associated with the accumulation of saturated very long chain fatty acids (SVLCFA). Oral administration of "Lorenzo's oil" (LO), a 4:1 mixture of glyceryl trioleate and glyceryl trierucate, normalizes the SVLCFA levels in plasma, but its clinical efficacy and the clinical indications for its use have been controversial for more than 15 years. We review the biochemical effects of LO administration and the rationale for its use and present a current appraisal of its capacity to reduce the risk for the childhood cerebral phenotype when administered to asymptomatic boys and to slow progression of adrenomyeloneuropathy in patients without cerebral involvement. We also present current efforts to provide definitive evaluation of its clinical efficacy and discuss its possible role in the new therapeutic opportunities that will arise if newborn screening for X-ALD is validated and implemented.

X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is caused by a defect in the gene ABCD1, which maps to Xq28 and codes for a peroxisomal membrane protein that is a member of the ATP-binding cassette transporter superfamily. X-ALD is panethnic and affects approximately 1:20,000 males. Phenotypes include the rapidly progressive childhood, adolescent, and adult cerebral forms; adrenomyeloneuropathy, which presents as slowly progressive paraparesis in adults; and Addison disease without neurologic manifestations. These phenotypes are frequently misdiagnosed, respectively, as attention-deficit hyperactivity disorder (ADHD), multiple sclerosis, or idiopathic Addison disease. Approximately 50% of female carriers develop a spastic paraparesis secondary to myelopathic changes similar to adrenomyeloneuropathy. Assays of very long chain fatty acids in plasma, cultured chorion villus cells and amniocytes, and mutation analysis permit presymptomatic and prenatal diagnosis, as well as carrier identification. The timely use of these assays is essential for genetic counseling and therapy. Early diagnosis and treatment can prevent overt Addison disease, and significantly reduce the frequency of the severe childhood cerebral phenotype. A promising new method for mass newborn screening has been developed, the implementation of which will have a profound effect on the diagnosis and therapy of X-ALD.