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

Terra incognita of glial cell dynamics in the etiology of leukodystrophies: Broadening disease and therapeutic perspectives

Neuroglial cells, also known as glia, are primarily characterized as auxiliary cells within the central nervous system (CNS). The recent findings have shed light on their significance in numerous physiological processes and their involvement in various neurological disorders. Leukodystrophies encompass an array of rare and hereditary neurodegenerative conditions that were initially characterized by the deficiency, aberration, or degradation of myelin sheath within CNS. The primary cellular populations that experience significant alterations are astrocytes, oligodendrocytes and microglia. These glial cells are either structurally or metabolically impaired due to inherent cellular dysfunction. Alternatively, they may fall victim to the accumulation of harmful by-products resulting from metabolic disturbances. In either situation, the possible replacement of glial cells through the utilization of implanted tissue or stem cell-derived human neural or glial progenitor cells hold great promise as a therapeutic strategy for both the restoration of structural integrity through remyelination and the amelioration of metabolic deficiencies. Various emerging treatment strategies like stem cell therapy, ex-vivo gene therapy, infusion of adeno-associated virus vectors, emerging RNA-based therapies as well as long-term therapies have demonstrated success in pre-clinical studies and show promise for rapid clinical translation. Here, we addressed various leukodystrophies in a comprehensive and detailed manner as well as provide prospective therapeutic interventions that are being considered for clinical trials. Further, we aim to emphasize the crucial role of different glial cells in the pathogenesis of leukodystrophies. By doing so, we hope to advance our understanding of the disease, elucidate underlying mechanisms, and facilitate the development of potential treatment interventions.

Burden of illness and mortality in men with Adrenomyeloneuropathy: a retrospective cohort study

BACKGROUND

Adrenomyeloneuropathy (AMN) is a neurodegenerative disease phenotype of X-linked adrenoleukodystrophy (ALD), resulting in progressive myeloneuropathy causing spastic paraparesis, sensory ataxia, and bowel/bladder symptoms. We conducted a retrospective cohort study using two large administrative databases to characterize mortality and the burden of illness in adult men with AMN in the US.

RESULTS

Healthcare resource use was assessed using a national commercial insurance claims database (2006-2021). Males with AMN ages 18-64 years and no evidence of cerebral ALD or other peroxisomal disorders were included and 1:4 matched on demographic characteristics to individuals without AMN. All study participants were followed for as long as observable. Patients with AMN were also identified in the Medicare Limited Dataset (2017-2022); mortality and age at death were compared with all Medicare enrollees. We identified 303 commercially insured men with AMN. Compared with non-AMN, individuals with AMN had significantly more inpatient hospital admissions (0.44 vs. 0.04 admissions/patient/year), outpatient clinic (8.88 vs. 4.1 visits/patient/year), outpatient hospital (5.33 vs. 0.99 visits/patient/year), and home healthcare visits (4.66 vs. 0.2 visits/patient/year), durable medical equipment claims (0.7 vs. 0.1 claims/patient/year), and prescription medication fills (18.1 vs. 5.4 fills/patient/year) (all p < 0.001). Average length-of-stay per hospitalization was also longer in AMN (8.88 vs. 4.3 days; p < 0.001). Rates of comorbidities were significantly more common in AMN compared to controls, including peripheral vascular disease (4.6% vs. 0.99%), chronic pulmonary disease (6.3% vs. 2.6%), and liver disease (5.6% vs. 0.88%), all p < 0.001. Among individuals age < 65 with Medicare disability coverage, mortality rates were 5.3x higher for adult AMN males (39.3% vs. 7.4%) and the age at death significantly younger (47.0 ± 11.3 vs. 56.5 ± 7.8 years), both p < 0.001. Among Medicare beneficiaries ages ≥ 65 mortality rates were 2.2x higher for men with AMN vs. those without AMN (48.6% vs. 22.4%), p < 0.001.

CONCLUSION

AMN imposes a substantial and underrecognized health burden on men, with higher healthcare utilization, greater medical comorbidity, higher mortality rates, and younger age at death.

Phase I clinical trial of intracerebral injection of lentiviral-ABCD1 for the treatment of cerebral adrenoleukodystrophy

This was a single-arm, multicenter, open-label phase I trial. Lentiviral vectors (LV) carrying the ABCD1 gene (LV-ABCD1) was directly injected into the brain of patients with childhood cerebral adrenoleukodystrophy (CCALD), and multi-site injection was performed. The injection dose increased from 200 to 1600 μL (vector titer: 1×109 TU/mL), and the average dose per kilogram body weight ranges from 8 to 63.6 μL/kg. The primary endpoint was safety, dose-exploration and immunogenicity and the secondary endpoint was initial evaluation of efficacy and the expression of ABCD1 protein. A total of 7 patients participated in this phase I study and were followed for 1 year. No injection-related serious adverse event or death occurred. Common adverse events associated with the injection were irritability (71%, 5/7) and fever (37.2 ℃-38.5 ℃, 57%, 4/7). Adverse events were mild and self-limited, or resolved within 3 d of symptomatic treatment. The maximal tolerable dose is 1600 μL. In 5 cases (83.3%, 5/6), no lentivirus associated antibodies were detected. The overall survival at 1-year was 100%. The ABCD1 protein expression was detected in neutrophils, monocytes and lymphocytes. This study suggests that the intracerebral injection of LV-ABCD1 for CCALD is safe and can achieve successful LV transduction in vivo; even the maximal dose did not increase the risk of adverse events. Furthermore, the direct LV-ABCD1 injection displayed low immunogenicity. In addition, the effectiveness of intracerebral LV-ABCD1 injection has been preliminarily demonstrated while further investigation is needed. This study has been registered in the Chinese Clinical Trial Registry (https://www.chictr.org.cn/, registration number: ChiCTR1900026649).

In vivo adenine base editing rescues adrenoleukodystrophy in a humanized mouse model

X-linked adrenoleukodystrophy (ALD), an inherited neurometabolic disorder caused by mutations in ABCD1, which encodes the peroxisomal ABC transporter, mainly affects the brain, spinal cord, adrenal glands, and testes. In ALD patients, very-long-chain fatty acids (VLCFAs) fail to enter the peroxisome and undergo subsequent β-oxidation, resulting in their accumulation in the body. It has not been tested whether in vivo base editing or prime editing can be harnessed to ameliorate ALD. We developed a humanized mouse model of ALD by inserting a human cDNA containing the pathogenic variant into the mouse Abcd1 locus. The humanized ALD model showed increased levels of VLCFAs. To correct the mutation, we tested both base editing and prime editing and found that base editing using ABE8e(V106W) could correct the mutation in patient-derived fibroblasts at an efficiency of 7.4%. Adeno-associated virus (AAV)-mediated systemic delivery of NG-ABE8e(V106W) enabled robust correction of the pathogenic variant in the mouse brain (correction efficiency: ∼5.5%), spinal cord (∼5.1%), and adrenal gland (∼2%), leading to a significant reduction in the plasma levels of C26:0/C22:0. This established humanized mouse model and the successful correction of the pathogenic variant using a base editor serve as a significant step toward treating human ALD disease.

Easily misdiagnosed X-linked adrenoleukodystrophy

BACKGROUND

Addison's disease and X-linked adrenoleukodystrophy (X-ALD) (Addison's-only) are two diseases that need to be identified. Addison's disease is easy to diagnose clinically when only skin and mucosal pigmentation symptoms are present. However, X-ALD (Addison's-only) caused by ABCD1 gene variation is ignored, thus losing the opportunity for early treatment. This study described two patients with initial clinical diagnosis of Addison's disease. However, they rapidly developed neurological symptoms triggered by infection. After further genetic testing, the two patients were diagnosed with X-ALD.

METHODS

We retrospectively analyzed X-ALD patients admitted to our hospital. Clinical features, laboratory test results, and imaging data were collected. Whole-exome sequencing was used in molecular genetics.

RESULTS

Two patients were included in this study. Both of them had significantly increased adrenocorticotropic hormone level and skin and mucosal pigmentation. They were initially clinically diagnosed with Addison's disease and received hydrocortisone treatment. However, both patients developed progressive neurological symptoms following infectious disease. Further brain magnetic resonance imaging was completed, and the results suggested demyelinating lesions. Molecular genetics suggested variations in the ABCD1 gene, which were c.109_110insGCCA (p.C39Pfs*156), c.1394-2 A > C (NM_000033), respectively. Therefore, the two patients were finally diagnosed with X-ALD, whose classification had progressed from X-ALD (Addison's-only) to childhood cerebral adrenoleukodystrophy (CCALD). Moreover, the infection exacerbates the demyelinating lesions and accelerates the onset of neurological symptoms. Neither the two variation sites in this study had been previously reported, which extends the ABCD1 variation spectrum.

CONCLUSIONS

Patients with only symptoms of adrenal insufficiency cannot be simply clinically diagnosed with Addison's disease. Being alert to the possibility of ABCD1 variation is necessary, and complete genetic testing is needed as soon as possible to identify X-ALD (Addison's-only) early to achieve regular monitoring of the disease and receive treatment early. In addition, infection, as a hit factor, may aggravate demyelinating lesions of CCALD. Thus, patients should be protected from external environmental factors to delay the progression of cerebral adrenoleukodystrophy.

Experiences of patients with metachromatic leukodystrophy, adrenoleukodystrophy, or Krabbe disease and the experiences of their family members: a qualitative systematic review

OBJECTIVE

This review aimed to synthesize the experiences of patients with metachromatic leukodystrophy, adrenoleukodystrophy, or Krabbe disease and the experiences of their families.

INTRODUCTION

Leukodystrophies are metabolic diseases caused by genetic mutations. There are multiple forms of the disease, varying in age of onset and symptoms. The progression of leukodystrophies worsens central nervous system symptoms and significantly affects the lives of patients and their families.

INCLUSION CRITERIA

Qualitative studies on the experiences of patients with leukodystrophies and their family members were included. These experiences included treatments such as enzyme replacement therapy and hematopoietic stem cell transplantation; effects of tracheostomy and gastrostomy; burdens on the family, coordinating care within the health care system, and family planning due to genetic disorders. This review considered studies in any setting.

METHODS

MEDLINE (Ovid), CINAHL Plus (EBSCOhost), APA PsycINFO (EBSCOhost), Scopus, and MedNar databases were searched on November 18, 2022. Study selection, critical appraisal, data extraction, and data synthesis were conducted in accordance with the JBI methodology for systematic reviews of qualitative evidence, and synthesized findings were evaluated according to the ConQual approach.

RESULTS

Eleven studies were eligible for synthesis, and 45 findings were extracted corresponding with participants' voices. Of these findings, 40 were unequivocal and 5 were credible. The diseases in the included studies were metachromatic leukodystrophy and adrenoleukodystrophy; no studies were identified for patients with Krabbe disease and their families. These findings were grouped into 11 categories and integrated into 3 synthesized findings, including i) providing care by family members and health care providers as physical symptoms progress, which relates to the effects of the characteristics of progressive leukodystrophies; ii) building medical teamwork to provide appropriate support services, comprising categories related to the challenges experienced with the health care system for patients with leukodystrophy and their families; and iii) coordinating family functions to accept and cope with the disease, which included categories related to family psychological difficulties and role divisions within the family. According to the ConQual criteria, the second synthesized finding had a low confidence level, and the first and third synthesized findings had a very low confidence level.

CONCLUSIONS

The synthesized findings of this review provide evidence on the experiences of patients with metachromatic leukodystrophy or adrenoleukodystrophy and their families. These findings indicate that there are challenges in managing a patient's physical condition and coordinating the health care system and family functions.

REVIEW REGISTRATION

PROSPERO CRD42022318805.

SUPPLEMENTAL DIGITAL CONTENT

A Japanese-language version of the abstract of this review is available [ http://links.lww.com/SRX/A49 ].

Brainstem dominant form of X-linked adrenoleukodystrophy with a novel ABCD1 missense variant: A case report and literature review

BACKGROUND

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder attributed to ABCD1 mutations. Case reports with predominant brainstem involvement are rare.

CASE PRESENTATION

In this study, we reported a plateau male worker of X-ALD characterized by progressive weakness accompanied by gait instability, mild nystagmus, and constipation. After 2 years of onset, a brain Magnetic Resonance Image (MRI) scan showed no abnormality but genetic analysis revealed a heterozygous mutation (c.1534G>A) in the ABCD1 gene. After 7 years of onset, although the patient was given aggressive dietary and symptomatic treatment in the course of the disease, a brain MRI scan showed predominantly brainstem damage, but serum concentrations of very long-chain fatty acids were normal, and he had been bedridden for almost 2 years with severe bladder dysfunction, forcing him to undergo cystostomy. The patient was discharged with improved urinary retention and renal function.

CONCLUSIONS

We reported an X-ALD patient with a novel ABCD1 variation characterized by brainstem damage and retrospectively summarized the clinical manifestation, MRI features, and genetic features of X-ALD patients with brainstem damage.

Childhood Cerebral Adrenoleukodystrophy: Case Report and Literature Review Advocating for Newborn Screening

Background

X-linked adrenoleukodystrophy (ALD) is a rare genetic disorder caused by a pathogenic variant of the ABCD1 gene, leading to impaired peroxisomal function and the accumulation of very long-chain fatty acids (VLCFAs). ALD presents a wide range of neurological and adrenal symptoms, ranging from childhood cerebral adrenoleukodystrophy to adrenomyeloneuropathy and adrenal insufficiency. Newborn screening (NBS) for ALD is available in some regions but remains lacking in others, such as India.

Case Presentation

We present a case of a 10-year-old boy with ALD who presented with seizures, progressive weakness, visual impairment, and adrenal insufficiency. Despite symptomatic management and dietary adjustments, the disease progressed rapidly, leading to respiratory failure and eventual demise. The diagnosis was confirmed through molecular analysis and elevated VLCFA levels. Neuroimaging revealed characteristic white matter changes consistent with ALD.

Conclusion

ALD is a devastating disease with no cure, emphasizing the importance of early detection through newborn screening and genetic testing. Management strategies include adrenal hormone therapy, gene therapy, and allogenic stem cell transplantation, as well as investigational treatments such as VLCFA normalization. Our case advocates the need for worldwide NBS and pediatric neurologic follow-up to enable early intervention and improve patient outcomes. Additionally, the association between ALD, recurrent febrile seizures, and unexplained developmental delay warrants further investigation to better understand disease progression and potential therapeutic targets.

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.

An Update on the Adult-Onset Hereditary Cerebellar Ataxias: Novel Genetic Causes and New Diagnostic Approaches

The hereditary cerebellar ataxias (HCAs) are rare, progressive neurologic disorders caused by variants in many different genes. Inheritance may follow autosomal dominant, autosomal recessive, X-linked or mitochondrial patterns. The list of genes associated with adult-onset cerebellar ataxia is continuously growing, with several new genes discovered in the last few years. This includes short-tandem repeat (STR) expansions in RFC1, causing cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS), FGF14-GAA causing spinocerebellar ataxia type 27B (SCA27B), and THAP11. In addition, the genetic basis for SCA4, has recently been identified as a STR expansion in ZFHX3. Given the large and growing number of genes, and different gene variant types, the approach to diagnostic testing for adult-onset HCA can be complex. Testing methods include targeted evaluation of STR expansions (e.g. SCAs, Friedreich ataxia, fragile X-associated tremor/ataxia syndrome, dentatorubral-pallidoluysian atrophy), next generation sequencing for conventional variants, which may include targeted gene panels, whole exome, or whole genome sequencing, followed by various potential additional tests. This review proposes a diagnostic approach for clinical testing, highlights the challenges with current testing technologies, and discusses future advances which may overcome these limitations. Implementing long-read sequencing has the potential to transform the diagnostic approach in HCA, with the overall aim to improve the diagnostic yield.

A novel ABCD1 gene mutation causes adrenomyeloneuropathy presenting with spastic paraplegia: A case report

RATIONALE

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene leading to very long chain fatty acid (VLCFA) accumulation. The disease demonstrates a spectrum of phenotypes including adrenomyeloneuropathy (AMN). We aimed to identify the genetic basis of disease in a patient presenting with AMN features in order to confirm the diagnosis, expand genetic knowledge of ABCD1 mutations, and elucidate potential genotype-phenotype associations to inform management.

PATIENT CONCERNS

A 29-year-old male presented with a 4-year history of progressive spastic paraplegia, weakness of lower limbs, fecal incontinence, sexual dysfunction, hyperreflexia, and positive Babinski and Chaddock signs.

DIAGNOSES

Neuroimaging revealed brain white matter changes and spinal cord thinning. Significantly elevated levels of hexacosanoic acid (C26:0) and tetracosanoic acid (C24:0) suggested very long chain fatty acids (VLCFA) metabolism disruption. Genetic testing identified a novel hemizygous ABCD1 mutation c.249dupC (p.F83fs). These findings confirmed a diagnosis of X-linked ALD with an AMN phenotype.

INTERVENTIONS

The patient received dietary counseling to limit VLCFA intake. Monitoring for adrenal insufficiency and consideration of Lorenzo's oil were advised. Genetic counseling and testing were offered to at-risk relatives.

OUTCOMES

At present, the patient continues to experience progressive paraplegia. Adrenal function remains normal thus far without steroid replacement. Family members have undergone predictive testing.

LESSONS

This case expands the known mutation spectrum of ABCD1-linked X-ALD, providing insight into potential genotype-phenotype correlations. A thoughtful diagnostic approach integrating clinical, biochemical and genetic data facilitated diagnosis. Findings enabled genetic counseling for at-risk relatives regarding this X-linked disorder.

Central precocious puberty in a boy with X-linked adrenoleukodystrophy caused by a novel ABCD1 mutation

X-linked adrenoleukodystrophy (X-ALD) is a rare genetic disorder caused by pathogenic variants in the ABCD1 gene. The symptoms include primary adrenal insufficiency (PAI), progressive spinal cord disease, inflammatory demyelinating cerebral disease, and primary hypogonadism. It is exceptionally rare that pediatric PAI is accompanied by central precocious puberty (CPP). The purpose of this study was to better understand the diversity of clinical manifestations of X-ALD and to identify the ABCD1 gene mutation in a case of a boy with X-ALD accompanied by CPP. We collected clinical, laboratory and imaging data, and used whole-exome sequencing (WES) analysis to evaluate the pathogenicity of the variant. We also predicted the potential deleterious effects of the novel mutation using Mutation Taster and generated three-dimensional protein structures using Swiss-Model and PyMOL Viewer software. The patient presented with PAI accompanied by CPP. Adrenal gland CT revealed adrenal hypoplasia. Gonadotropin-releasing hormone stimulation tests revealed CPP. WES revealed a novel variant (c.1376dup) in the ABCD1 gene, which resulted in a reading frameshift and a premature termination codon (p.Leu461ProfsTer95). Sanger sequencing confirmed that the variant was inherited from his heterozygous mother. Mutation Taster predicted that the variant could be harmful. The overall three-dimensional structures of the mutant wild-type proteins were visually distinct. Our results shed light on additional aspects of X-ALD. The premature activation of the hypothalamic-pituitary-gonadal axis may possibly be related to the pathogenic ABCD1 gene mutation.

The pathology of X-linked adrenoleukodystrophy: tissue specific changes as a clue to pathophysiology

Although the pathology of X-linked adrenoleukodystrophy (ALD) is well described, it represents the end-stage of neurodegeneration. It is still unclear what cell types are initially involved and what their role is in the disease process. Revisiting the seminal post-mortem studies from the 1970s can generate new hypotheses on pathophysiology. This review describes (histo)pathological changes of the brain and spinal cord in ALD. It aims at integrating older works with current insights and at providing an overarching theory on the pathophysiology of ALD. The data point to an important role for axons and glia in the pathology of both the myelopathy and leukodystrophy of ALD. In-depth pathological analyses with new techniques could help further unravel the sequence of events behind the pathology of ALD.

Patient-reported impact of symptoms in adrenoleukodystrophy (PRISM-ALD)

BACKGROUND

Adrenoleukodystrophy (ALD) is a multifaceted, X-linked, neurodegenerative disorder that comprises several clinical phenotypes. ALD affects patients through a variety of physical, emotional, social, and other disease-specific factors that collectively contribute to disease burden. To facilitate clinical care and research, it is important to identify which symptoms are most common and relevant to individuals with any subtype of ALD.

METHODS

We conducted semi-structured qualitative interviews and an international cross-sectional study to determine the most prevalent and important symptoms of ALD. Our study included adult participants with a diagnosis of ALD who were recruited from national and international patient registries. Responses were categorized by age, sex, disease phenotype, functional status, and other demographic and clinical features.

RESULTS

Seventeen individuals with ALD participated in qualitative interviews, providing 1709 direct quotes regarding their symptomatic burden. One hundred and nine individuals participated in the cross-sectional survey study, which inquired about 182 unique symptoms representing 24 distinct symptomatic themes. The symptomatic themes with the highest prevalence in the overall ALD sample cohort were problems with balance (90.9%), limitations with mobility or walking (87.3%), fatigue (86.4%), and leg weakness (86.4%). The symptomatic themes with the highest impact scores (on a 0-4 scale with 4 being the most severe) were trouble getting around (2.35), leg weakness (2.25), and problems with balance (2.21). A higher prevalence of symptomatic themes was associated with functional disability, employment disruption, and speech impairment.

CONCLUSIONS

There are many patient-relevant symptoms and themes that contribute to disease burden in individuals with ALD. These symptoms, identified by those having ALD, present key targets for further research and therapeutic development.

Role of Basal Forebrain Neurons in Adrenomyeloneuropathy in Mice and Humans

OBJECTIVE

X-linked adrenoleukodystrophy is caused by mutations in the peroxisomal half-transporter ABCD1. The most common manifestation is adrenomyeloneuropathy, a hereditary spastic paraplegia of adulthood. The present study set out to understand the role of neuronal ABCD1 in mice and humans with adrenomyeloneuropathy.

METHODS

Neuronal expression of ABCD1 during development was assessed in mice and humans. ABCD1-deficient mice and human brain tissues were examined for corresponding pathology. Next, we silenced ABCD1 in cholinergic Sh-sy5y neurons to investigate its impact on neuronal function. Finally, we tested adeno-associated virus vector-mediated ABCD1 delivery to the brain in mice with adrenomyeloneuropathy.

RESULTS

ABCD1 is highly expressed in neurons located in the periaqueductal gray matter, basal forebrain and hypothalamus. In ABCD1-deficient mice (Abcd1-/y), these structures showed mild accumulations of α-synuclein. Similarly, healthy human controls had high expression of ABCD1 in deep gray nuclei, whereas X-ALD patients showed increased levels of phosphorylated tau, gliosis, and complement activation in those same regions, albeit not to the degree seen in neurodegenerative tauopathies. Silencing ABCD1 in Sh-sy5y neurons impaired expression of functional proteins and decreased acetylcholine levels, similar to observations in plasma of Abcd1-/y mice. Notably, hind limb clasping in Abcd1-/y mice was corrected through transduction of ABCD1 in basal forebrain neurons following intracerebroventricular gene delivery.

INTERPRETATION

Our study suggests that the basal forebrain-cortical cholinergic pathway may contribute to dysfunction in adrenomyeloneuropathy. Rescuing peroxisomal transport activity in basal forebrain neurons and supporting glial cells might represent a viable therapeutic strategy. ANN NEUROL 2024;95:442-458.

Accelerated Course of Cerebral Adrenoleukodystrophy After Coronavirus Disease 2019 Infection

BACKGROUND

Coronavirus disease 2019 (COVID-19) can not only infect the respiratory system but also affect the nervous system through the release of inflammatory factors. Our study aimed to investigate the effect of COVID-19 infection on cerebral adrenoleukodystrophy (ALD).

METHODS

Changes in the neurological symptoms of cerebral ALD after infection with COVID-19 from January 2022 to February 2023 were retrospectively analyzed. The primary assessment indicator was the Neurologic Function Scale (NFS) score.

RESULTS

A total of 17 male patients with cerebral ALD were enrolled, with a median age of 101 months (80 to 151 months). Among them, 11 (11 of 17, 64.7%) developed an exacerbation of neurological symptoms after COVID-19 infection. Two patients with NFS = 0 started presenting with neurological symptoms after infection. Fifteen patients were in the advanced stage (NFS >1 and/or Loes score >9), of which nine did not progress to major functional disabilities (MFDs). Seven of the nine patients (77.8%) experienced an increase in NFS scores, ranging from 1 to 9 points, within two weeks of COVID-19 infection, with four of them experiencing MFDs. For the other six patients who had progressed to MFDs, there was not much room for further degeneration, so the NFS score did not increase after COVID-19 infection. No deaths related to COVID-19 infection occurred.

CONCLUSIONS

COVID-19 infection may aggravate neurological symptoms of cerebral ALD, particularly among patients who have not yet progressed to MFDs. Therefore, COVID-19 may accelerate the course of cerebral ALD, so protecting patients from infection is essential for maintaining the stability of the disease.

A patient with X-linked adrenoleukodystrophy presenting with central precocious puberty: a case report

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder caused by the variations in the ATP-binding cassette sub-family D member 1 (ABCD1) gene. This study is the first to report central precocious puberty (CPP) in individuals with X-ALD. A 6-year-old boy exhibited mucocutaneous pigmentation, increased plasma adrenocorticotropic hormone levels, and elevated very long-chain fatty acids (VLCFA). We identified a variant, c.1826A>G (p. Glu609Gly), in exon 8 of the ABCD1 gene in the proband. Additionally, he displayed rapid growth, testicular volume of 5-6 mL, the onset of pubic hair, and pubertal levels of luteinizing hormone (LH), all meeting the diagnostic criteria for CPP.

The peroxisome: an update on mysteries 3.0

Peroxisomes are highly dynamic, oxidative organelles with key metabolic functions in cellular lipid metabolism, such as the β-oxidation of fatty acids and the synthesis of myelin sheath lipids, as well as the regulation of cellular redox balance. Loss of peroxisomal functions causes severe metabolic disorders in humans. Furthermore, peroxisomes also fulfil protective roles in pathogen and viral defence and immunity, highlighting their wider significance in human health and disease. This has sparked increasing interest in peroxisome biology and their physiological functions. This review presents an update and a continuation of three previous review articles addressing the unsolved mysteries of this remarkable organelle. We continue to highlight recent discoveries, advancements, and trends in peroxisome research, and address novel findings on the metabolic functions of peroxisomes, their biogenesis, protein import, membrane dynamics and division, as well as on peroxisome-organelle membrane contact sites and organelle cooperation. Furthermore, recent insights into peroxisome organisation through super-resolution microscopy are discussed. Finally, we address new roles for peroxisomes in immune and defence mechanisms and in human disorders, and for peroxisomal functions in different cell/tissue types, in particular their contribution to organ-specific pathologies.

Leukodystrophy Imaging: Insights for Diagnostic Dilemmas

Leukodystrophies, a group of rare demyelinating disorders, mainly affect the CNS. Clinical presentation of different types of leukodystrophies can be nonspecific, and thus, imaging techniques like MRI can be used for a more definitive diagnosis. These diseases are characterized as cerebral lesions with characteristic demyelinating patterns which can be used as differentiating tools. In this review, we talk about these MRI study findings for each leukodystrophy, associated genetics, blood work that can help in differentiation, emerging diagnostics, and a follow-up imaging strategy. The leukodystrophies discussed in this paper include X-linked adrenoleukodystrophy, metachromatic leukodystrophy, Krabbe's disease, Pelizaeus-Merzbacher disease, Alexander's disease, Canavan disease, and Aicardi-Goutières Syndrome.

Magnetic resonance imaging enhancement of spinal nerve roots in a boy with X-linked adrenoleukodystrophy before diagnosis of chronic inflammatory demyelinating polyneuropathy

We present a boy with X-linked adrenoleukodystrophy (X-ALD) who was found to have lumbar nerve root enhancement on a screening MRI of the spine. The MRI was performed for lower extremity predominant symptoms. Several weeks after this MRI, he developed leg pain and was averse to walking long distances. He was diagnosed with Chronic Inflammatory Demyelinating Polyneuropathy (CIDP) with electromyography, nerve conduction studies, and serial imaging. His case is consistent with CIDP in association with X-ALD based on improvement with intravenous immunoglobulin (IVIG) with continued contrast enhancement and lower extremity symptoms 8 weeks after his initial scans. Contrast enhancement of nerve roots has not been previously described in X-ALD. Nerve root enhancement has been seen in other leukodystrophies such as globoid cell leukodystrophy and metachromatic leukodystrophy. This case also demonstrates comorbid X-ALD with CIDP and highlights possible mechanisms from the literature for this association. We also review the broad differential of cauda equina nerve root enhancement.

Update on leukodystrophies and developing trials

Leukodystrophies are a heterogeneous group of rare genetic disorders primarily affecting the white matter of the central nervous system. These conditions can present a diagnostic challenge, requiring a comprehensive approach that combines clinical evaluation, neuroimaging, metabolic testing, and genetic testing. While MRI is the main tool for diagnosis, advances in molecular diagnostics, particularly whole-exome sequencing, have significantly improved the diagnostic yield. Timely and accurate diagnosis is crucial to guide symptomatic treatment and assess eligibility to participate in clinical trials. Despite no specific cure being available for most leukodystrophies, gene therapy is emerging as a potential treatment avenue, rapidly advancing the therapeutic prospects in leukodystrophies. This review will explore diagnostic and therapeutic strategies for leukodystrophies, with particular emphasis on new trials.

The Clinical Spectrum of Adrenoleukodystrophy at a Portuguese Tertiary Hospital: Case Series and Review of Literature

Adrenoleukodystrophy, a rare genetic disease associated with the X chromosome (X-ALD - X-linked adrenoleukodystrophy), predominantly affects males and stems from mutations in the ABCD1 gene, responsible for transporting very long chain fatty acids (VLCFA) into peroxisomes. It leads to adrenal insufficiency (AI) and axonal demyelination. In males, the phenotype varies from isolated adrenocortical insufficiency and progressive myelopathy to cerebral adrenoleukodystrophy (CALD). The aim of this case series is to characterize patients with different clinical presentations of X-ALD with follow-up at a tertiary Portuguese hospital. All four patients were males, and the median age at the diagnosis was 5 years. Three patients were diagnosed through family screening, with the oldest already displaying hyperpigmentation. Two distinct forms were identified: adolescent CALD (25%) and isolated primary adrenal insufficiency (75%). Analytical studies revealed elevated plasma VLCFA levels in all cases, and genetic analysis demonstrated two different mutations in the ABCD1 gene. This disorder requires early diagnosis for improved prognosis. Screening male children with primary AIfor X-ALD using a VLCFA panel should be considered, particularly after ruling out the most common causes or when learning difficulties are evident. Genetic confirmation of the diagnosis is essential, enabling genetic counseling, family planning, and preimplantation genetic diagnosis.

Genetic and phenotypic spectrum of non-21-hydroxylase-deficiency primary adrenal insufficiency in childhood: data from 111 Chinese patients

BACKGROUND

Primary adrenal insufficiency (PAI) is a rare but life-threatening condition. Differential diagnosis of numerous causes of PAI requires a thorough understanding of the condition.

METHODS

To describe the genetic composition and presentations of PAI. The following data were collected retrospectively from 111 patients with non-21OHD with defined genetic diagnoses: demographic information, onset age, clinical manifestations, laboratory findings and genetic results. Patients were divided into four groups based on the underlying pathogenesis: (1) impaired steroidogenesis, (2) adrenal hypoplasia, (3) resistance to adrenocorticotropic hormone (ACTH) and (4) adrenal destruction. The age of onset was compared within the groups.

RESULTS

Mutations in the following genes were identified: NR0B1 (n=39), STAR (n=33), CYP11B1 (n=12), ABCD1 (n=8), CYP17A1 (n=5), HSD3B2 (n=4), POR (n=4), MRAP (n=2), MC2R (n=1), CYP11A1 (n=1), LIPA (n=1) and SAMD9 (n=1). Frequent clinical manifestations included hyperpigmentation (73.0%), dehydration (49.5%), vomiting (37.8%) and abnormal external genitalia (23.4%). Patients with adrenal hypoplasia typically presented manifestations earlier than those with adrenal destruction but later than those with impaired steroidogenesis (both p<0.01). The elevated ACTH (92.6%) and decreased cortisol (73.5%) were the most common laboratory findings. We generated a differential diagnosis flowchart for PAI using the following clinical features: 17-hydroxyprogesterone, very-long-chain fatty acid, external genitalia, hypertension and skeletal malformation. This flowchart identified 84.8% of patients with PAI before next-generation DNA sequencing.

CONCLUSIONS

STAR and NR0B1 were the most frequently mutated genes in patients with non-21OHD PAI. Age of onset and clinical characteristics were dependent on aetiology. Combining clinical features and molecular tests facilitates accurate diagnosis.

Newborn screening for adrenoleukodystrophy: International experiences and challenges

X-linked adrenoleukodystrophy (XALD) is the most common leukodystrophy. It has an estimated incidence of around 1/17.000, and a variable phenotype. Following the passage of Aidens Law, New York became the first state to implement a newborn screening for XALD in 2013. Since then, 38 American states, Taiwan, and the Netherlands have included XALD in their NBS program, and Japan and Italy have ongoing pilot studies. Screening for XALD allows for early, potentially lifesaving treatment of adrenal insufficiency and cerebral demyelination but is also a complex subject, due to our limited understanding of the natural history and lack of prognostic biomarkers. Screening protocols and algorithms vary between countries and states, and results and experiences gained so far are important for the future implementation of XALD NBS in other countries. In this review, we have examined the algorithms, methodologies, and outcomes used, as well as how common challenges are addressed in countries/states that have experience using NBS for XALD. We identified 14 peer-reviewed reports on NBS for XALD. All studies presented methods for detecting XALD at birth by NBS using a combination of mass spectrometry and ABCD1 gene sequencing. This has allowed for early surveillance of presymptomatic XALD patients, and the possibility for early detection and timely treatment of XALD manifestations. Obstacles to NBS for XALD include how to deal with variants of unknown significance, whether to screen females, and the ethical concerns of an NBS for a disease where we have limited understanding of natural history and phenotype/genotype correlation.

X-linked adrenoleukodystrophy and primary adrenal insufficiency

X-linked adrenoleukodystrophy (X-ALD; OMIM:300100) is a progressive neurodegenerative disorder caused by a congenital defect in the ATP-binding cassette transporters sub-family D member 1 gene (ABCD1) producing adrenoleukodystrophy protein (ALDP). According to population studies, X-ALD has an estimated birth prevalence of 1 in 17.000 subjects (considering both hemizygous males and heterozygous females), and there is no evidence that this prevalence varies among regions or ethnic groups. ALDP deficiency results in a defective peroxisomal β-oxidation of very long chain fatty acids (VLCFA). As a consequence of this metabolic abnormality, VLCFAs accumulate in nervous system (brain white matter and spinal cord), testis and adrenal cortex. All X-ALD affected patients carry a mutation on the ABCD1 gene. Nevertheless, patients with a defect on the ABCD1 gene can have a dramatic difference in the clinical presentation of the disease. In fact, X-ALD can vary from the most severe cerebral paediatric form (CerALD), to adult adrenomyeloneuropathy (AMN), Addison-only and asymptomatic forms. Primary adrenal insufficiency (PAI) is one of the main features of X-ALD, with a prevalence of 70% in ALD/AMN patients and 5% in female carriers. The pathogenesis of X-ALD related PAI is still unclear, even if a few published data suggests a defective adrenal response to ACTH, related to VLCFA accumulation with progressive disruption of adrenal cell membrane function and ACTH receptor activity. The reason why PAI develops only in a proportion of ALD/AMN patients remains incompletely understood. A growing consensus supports VLCFA assessment in all male children presenting with PAI, as early diagnosis and start of therapy may be essential for X-ALD patients. Children and adults with PAI require individualized glucocorticoid replacement therapy, while mineralocorticoid therapy is needed only in a few cases after consideration of hormonal and electrolytes status. Novel approaches, such as prolonged release glucocorticoids, offer potential benefit in optimizing hormonal replacement for X-ALD-related PAI. Although the association between PAI and X-ALD has been observed in clinical practice, the underlying mechanisms remain poorly understood. This paper aims to explore the multifaceted relationship between PAI and X-ALD, shedding light on shared pathophysiology, clinical manifestations, and potential therapeutic interventions.

Diagnosing X-Linked Adrenoleukodystrophy after Implementation of Newborn Screening: A Reference Laboratory Perspective

Adrenoleukodystrophy (ALD) is caused by pathogenic variants in the ABCD1 gene, encoding for the adrenoleukodystrophy protein (ALDP), leading to defective peroxisomal β-oxidation of very long-chain and branched-chain fatty acids (VLCFA). ALD manifests in both sexes with a spectrum of phenotypes, but approximately 35% of affected males develop childhood cerebral adrenoleukodystrophy (CCALD), which is lethal without hematopoietic stem cell transplant performed before symptoms start. Hence, ALD was added to the Recommended Uniform Screening Panel after the successful implementation in New York State (2013-2016). To date, thirty-five states have implemented newborn screening (NBS) for ALD, and a few programs have reported on the successes and challenges experienced. However, the overall impact of NBS on early detection of ALD has yet to be fully determined. Here, we conducted a retrospective analysis of VLCFA testing performed by our reference laboratory (ARUP Laboratories, Salt Lake City, UT, USA) over 10 years. Rate of detection, age at diagnosis, and male-to-female ratio were evaluated in patients with abnormal results before and after NBS implementation. After NBS inclusion, a significant increase in abnormal results was observed (471/6930, 6.8% vs. 384/11,670, 3.3%; p < 0.0001). Patients with ALDP deficiency identified via NBS were significantly younger (median age: 30 days vs. 21 years; p < 0.0001), and males and females were equally represented. ALD inclusion in NBS programs has increased pre-symptomatic detection of this disease, which is critical in preventing adrenal crisis as well as the severe cerebral form.

Gene and Cellular Therapies for Leukodystrophies

Leukodystrophies are a heterogenous group of inherited, degenerative encephalopathies, that if left untreated, are often lethal at an early age. Although some of the leukodystrophies can be treated with allogeneic hematopoietic stem cell transplantation, not all patients have suitable donors, and new treatment strategies, such as gene therapy, are rapidly being developed. Recent developments in the field of gene therapy for severe combined immune deficiencies, Leber's amaurosis, epidermolysis bullosa, Duchenne's muscular dystrophy and spinal muscular atrophy, have paved the way for the treatment of leukodystrophies, revealing some of the pitfalls, but overall showing promising results. Gene therapy offers the possibility for overexpression of secretable enzymes that can be released and through uptake, allow cross-correction of affected cells. Here, we discuss some of the leukodystrophies that have demonstrated strong potential for gene therapy interventions, such as X-linked adrenoleukodystrophy (X-ALD), and metachromatic leukodystrophy (MLD), which have reached clinical application. We further discuss the advantages and disadvantages of ex vivo lentiviral hematopoietic stem cell gene therapy, an approach for targeting microglia-like cells or rendering cross-correction. In addition, we summarize ongoing developments in the field of in vivo administration of recombinant adeno-associated viral (rAAV) vectors, which can be used for direct targeting of affected cells, and other recently developed molecular technologies that may be applicable to treating leukodystrophies in the future.

Early Detection of Adrenal Insufficiency: The Impact of Newborn Screening for Adrenoleukodystrophy

CONTEXT

Males with adrenoleukodystrophy (ALD) have an 80% lifetime risk of developing adrenal insufficiency (AI), which can be life-threatening when undetected. Newborn screening (NBS) for ALD has been implemented in 29 states, yet the impact of NBS upon clinical management has not been reported.

OBJECTIVE

To investigate whether the implementation of NBS has altered the time to diagnosis of AI in children with ALD.

DESIGN

We conducted a retrospective medical chart review of pediatric patients with ALD.

SETTING

All patients were seen in a leukodystrophy clinic in an academic medical center.

PATIENTS

We included all pediatric patients with ALD who were seen between May 2006 and January 2022. We identified 116 patients (94% boys).

MAIN OUTCOME MEASURES

We extracted information about ALD diagnosis in all patients and AI surveillance, diagnosis, and treatment in boys with ALD.

RESULTS

Thirty-one (27%) patients were diagnosed with ALD by NBS, and 85 (73%) were diagnosed outside the newborn period. The prevalence of AI among boys in our patient population was 74%. AI diagnosis was made significantly earlier in boys diagnosed with ALD by NBS than in boys diagnosed outside the newborn period (median [IQR] age of diagnosis = 6.7 [3.9, 12.12] months vs 6.05 [3.74, 8.35] years) (P < .001). When maintenance dose of glucocorticoids were initiated, there were significant differences in ACTH and peak cortisol levels in patients diagnosed by NBS and outside the newborn period.

CONCLUSIONS

Our results suggest that implementing NBS for ALD leads to significantly earlier detection of AI and earlier initiation of glucocorticoid supplementation in boys affected by ALD.

The Physiological and Pathological Role of Acyl-CoA Oxidation

Fatty acid metabolism, including β-oxidation (βOX), plays an important role in human physiology and pathology. βOX is an essential process in the energy metabolism of most human cells. Moreover, βOX is also the source of acetyl-CoA, the substrate for (a) ketone bodies synthesis, (b) cholesterol synthesis, (c) phase II detoxication, (d) protein acetylation, and (d) the synthesis of many other compounds, including N-acetylglutamate-an important regulator of urea synthesis. This review describes the current knowledge on the importance of the mitochondrial and peroxisomal βOX in various organs, including the liver, heart, kidney, lung, gastrointestinal tract, peripheral white blood cells, and other cells. In addition, the diseases associated with a disturbance of fatty acid oxidation (FAO) in the liver, heart, kidney, lung, alimentary tract, and other organs or cells are presented. Special attention was paid to abnormalities of FAO in cancer cells and the diseases caused by mutations in gene-encoding enzymes involved in FAO. Finally, issues related to α- and ω- fatty acid oxidation are discussed.

Interval between contrast administration and T1-weighted MRI for cerebral adrenoleukodystrophy: a single-case observation

In adrenoleukodystrophy (ALD), contrast enhancement (CE) is a disease activity marker, but there is uncertainty about the optimal delay, if any, between contrast injection and magnetic resonance imaging (MRI) acquisition to avoid false-negative results. We acquired axial two-dimensional (2D) and three-dimensional (3D) T1-weighted gradient-echo every 6 min from 0 to 36 min after contrast administration (gadobutrol 0.1 mmol/kg) in an ALD patient with enlarging white matter lesions and progressive neuropsychological symptoms, using a 3-T magnet. The image signal over time was qualitatively assessed and measured in two regions of interest. On 3D sequences, no definite CE was appreciated, whereas on 2D sequences, CE was noticed after 6 min and definitely evident after 12 min, when 73% of the maximum signal intensity was measured. In ALD subjects, contrast-enhanced 2D T1-weighted gradient-echo sequences acquired at least 10 min after contrast injection may be considered to reduce false negative results.Relevance statementOur report is the first attempt to find an optimal delay between contrast administration and T1-weighted acquisition in cALD patients in order to correctly detect disease activity and avoid false negative results.Key points• The optimal time between contrast injection and image acquisition for MRI of adrenoleukodystrophy is unknown.• Contrast enhancement predicts adrenoleukodystrophy progression and could help patient's selection for the therapy.• We acquired two post-contrast T1-GRE-2D/3D sequences several times to find the best injection-time.• T1-weighted 2D GRE resulted more sensitive than T1-weighted 3D GRE even after long intervals from injection.• A delay of about 10 min may minimize false negatives.

Attitudes of Patients with Adrenoleukodystrophy towards Sex-Specific Newborn Screening

Newborn screening (NBS) for X-linked adrenoleukodystrophy (ALD) can identify affected individuals before the onset of life-threatening manifestations. Some countries have decided to only screen boys (sex-specific screening). This study investigates the attitudes of individuals with ALD towards sex-specific NBS for ALD. A questionnaire was sent to all patients in the Dutch ALD cohort. Invitees were asked who they thought should be screened for ALD: only boys, both boys and girls or neither. The motives and background characteristics of respondents were compared between screening preferences. Out of 108 invitees, 66 participants (61%), 38 men and 28 women, participated in this study. The majority (n = 53, 80%) favored screening both newborn boys and girls for ALD, while 20% preferred boys only. None of the respondents felt that newborns should not be screened for ALD. There were no differences in the background characteristics of the respondents between screening preferences. Our study revealed a diverse range of motivations underlying respondents' screening preferences. This study is one of the first to investigate the attitudes of patients towards sex-specific screening for ALD. The outcomes of this study can offer insights to stakeholders engaged in the implementation of NBS programs. ALD patients are important stakeholders who can provide valuable input in this process.

ABCD1 Transporter Deficiency Results in Altered Cholesterol Homeostasis

X-linked adrenoleukodystrophy (X-ALD), the most common peroxisomal disorder, is caused by mutations in the peroxisomal transporter ABCD1, resulting in the accumulation of very long-chain fatty acids (VLCFA). Strongly affected cell types, such as oligodendrocytes, adrenocortical cells and macrophages, exhibit high cholesterol turnover. Here, we investigated how ABCD1 deficiency affects cholesterol metabolism in human X-ALD patient-derived fibroblasts and CNS tissues of Abcd1-deficient mice. Lipidome analyses revealed increased levels of cholesterol esters (CE), containing both saturated VLCFA and mono/polyunsaturated (V)LCFA. The elevated CE(26:0) and CE(26:1) levels remained unchanged in LXR agonist-treated Abcd1 KO mice despite reduced total C26:0. Under high-cholesterol loading, gene expression of SOAT1, converting cholesterol to CE and lipid droplet formation were increased in human X-ALD fibroblasts versus healthy control fibroblasts. However, the expression of NCEH1, catalysing CE hydrolysis and the cholesterol transporter ABCA1 and cholesterol efflux were also upregulated. Elevated Soat1 and Abca1 expression and lipid droplet content were confirmed in the spinal cord of X-ALD mice, where expression of the CNS cholesterol transporter Apoe was also elevated. The extent of peroxisome-lipid droplet co-localisation appeared low and was not impaired by ABCD1-deficiency in cholesterol-loaded primary fibroblasts. Finally, addressing steroidogenesis, progesterone-induced cortisol release was amplified in X-ALD fibroblasts. These results link VLCFA to cholesterol homeostasis and justify further consideration of therapeutic approaches towards reducing VLCFA and cholesterol levels in X-ALD.

Childhood cerebral adrenoleukodystrophy (CCALD) in France: epidemiology, natural history, and burden of disease - A population-based study

BACKGROUND

X-linked adrenoleukodystrophy (ALD) is a rare metabolic and neurodegenerative disorder belonging to the group of leukodystrophies, with an estimated incidence around 1:25 000 newborns worldwide, mostly among men. Childhood Cerebral ALD (CCALD) is the most severe form with a poor prognosis if not properly treated during the first years of life. Currently, only allogeneic hematopoietic stem cell transplantation (allo-HSCT) is widely available for CCALD treatment. To date, there is a lack of data regarding CCALD epidemiology, natural history, and current management in France. This knowledge is crucial for the development of new therapies such as gene therapies. In this context, the French National Health Data System (SNDS) is a particularly indicated database to collect information meeting these needs. A non-interventional, national, real-life, retrospective study was performed using secondary data from the national ALD registry (LEUKOFRANCE) and SNDS. CCALD patients detected between 2009 and 2018 and successfully matched between LEUKOFRANCE and SNDS were included in this study. Index date was defined as the first CCALD event detected during study period. Subgroups of patients with sufficient follow-up (6 months) and history (1 year) available around index date were analyzed to assess CCALD burden and natural history.

RESULTS

52 patients were included into the matched cohort. Median annual incidence of CCALD was estimated at 4 patients. Median age at CCALD diagnosis was 7.0 years. Among patients without allo-HSCT, five-year overall survival was 66.6%, with 93.3% of them presenting at least one CCALD symptom and 62.1% presenting a least one major functional disability (MFD). Among patients with allo-HSCT, five-year overall survival was 94.4%, with only 11.1% of patients presenting CCALD symptoms, and 16.7% of presenting a MFD. Mean annualized costs were almost twice as important among patients without allo-HSCT, with 49,211€, 23,117€, respectively. Costs were almost exclusively represented by hospitalizations.

CONCLUSIONS

To the best of our knowledge, this is the most up to date study analyzing CCALD epidemiology, clinical and economic burden in France. The necessity of a precocious management with HSCT highlight the potential benefits of including an expanded screening program among newborns, coupled with family screenings when a mutation is detected.

Lysosomal cholesterol accumulation is commonly found in most peroxisomal disorders and reversed by 2-hydroxypropyl-β-cyclodextrin

Peroxisomal disorders (PDs) are a heterogenous group of diseases caused by defects in peroxisome biogenesis or functions. X-linked adrenoleukodystrophy is the most prevalent form of PDs and results from mutations in the ABCD1 gene, which encodes a transporter mediating the uptake of very long-chain fatty acids (VLCFAs). The curative approaches for PDs are very limited. Here, we investigated whether cholesterol accumulation in the lysosomes is a biochemical feature shared by a broad spectrum of PDs. We individually knocked down fifteen PD-associated genes in cultured cells and found ten induced cholesterol accumulation in the lysosome. 2-Hydroxypropyl-β-cyclodextrin (HPCD) effectively alleviated the cholesterol accumulation phenotype in PD-mimicking cells through reducing intracellular cholesterol content as well as promoting cholesterol redistribution to other cellular membranes. In ABCD1 knockdown cells, HPCD treatment lowered reactive oxygen species and VLCFA to normal levels. In Abcd1 knockout mice, HPCD injections reduced cholesterol and VLCFA sequestration in the brain and adrenal cortex. The plasma levels of adrenocortical hormones were increased and the behavioral abnormalities were greatly ameliorated upon HPCD administration. Together, our results suggest that defective cholesterol transport underlies most, if not all, PDs, and that HPCD can serve as a novel and effective strategy for the treatment of PDs.

Adult-onset leukodystrophies: a practical guide, recent treatment updates, and future directions

Adult-onset leukodystrophies though individually rare are not uncommon. This group includes several disorders with isolated adult presentations, as well as several childhood leukodystrophies with attenuated phenotypes that present at a later age. Misdiagnoses often occur due to the clinical and radiological overlap with common acquired disorders such as infectious, immune, inflammatory, vascular, metabolic, and toxic etiologies. Increased prevalence of non-specific white matter changes in adult population poses challenges during diagnostic considerations. Clinico-radiological spectrum and molecular landscape of adult-onset leukodystrophies have not been completely elucidated at this time. Diagnostic approach is less well-standardized when compared to the childhood counterpart. Absence of family history and reduced penetrance in certain disorders frequently create a dilemma. Comprehensive evaluation and molecular confirmation when available helps in prognostication, early initiation of treatment in certain disorders, enrollment in clinical trials, and provides valuable information for the family for reproductive counseling. In this review article, we aimed to formulate an approach to adult-onset leukodystrophies that will be useful in routine practice, discuss common adult-onset leukodystrophies with usual and unusual presentations, neuroimaging findings, recent advances in treatment, acquired mimics, and provide an algorithm for comprehensive clinical, radiological, and genetic evaluation that will facilitate early diagnosis and consider active treatment options when available. A high index of suspicion, awareness of the clinico-radiological presentations, and comprehensive genetic evaluation are paramount because treatment options are available for several disorders when diagnosed early in the disease course.

Effect of vitamin D supplementation on cerebral blood flow in male patients with adrenoleukodystrophy

One-third of boys with X-linked adrenoleukodystrophy (ALD) develop inflammatory demyelinating lesions, typically at the splenium. These lesions share similarities with multiple sclerosis, including cerebral hypoperfusion and links to vitamin D insufficiency. We hypothesized that increasing vitamin D levels would increase cerebral blood flow (CBF) in ALD boys. We conducted an exploratory analysis of vitamin D supplementation and CBF using all available data from participants enrolled in a recent single-arm interventional study of vitamin D supplementation in boys with ALD. We measured whole brain and splenium CBF using arterial spin labeling (ASL) from three study time points (baseline, 6 months, and 12 months). We used linear generalized estimating equations to evaluate CBF changes between time points and to test for an association between CBF and vitamin D. ASL data were available for 16 participants, aged 2-22 years. Mean vitamin D levels increased by 72.7% (p < .001) after 6 months and 88.6% (p < .01) after 12 months. Relative to baseline measures, mean CBF of the whole brain (6 months: +2.5%, p = .57; 12 months: +6.1%, p = .18) and splenium (6 months: +1.2%, p = .80; 12 months: +7.4%, p = .058) were not significantly changed. Vitamin D levels were positively correlated with CBF in the splenium (slope = .59, p < .001). In this exploratory analysis, we observed a correlation between vitamin D levels and splenial CBF in ALD boys. We confirm the feasibility of measuring CBF in this brain region and population, but further work is needed to establish a causal role for vitamin D in modulating CBF.

Exploratory study of autophagy inducer sirolimus for childhood cerebral adrenoleukodystrophy

Objectives

X-linked adrenoleukodystrophy (ALD) is a peroxisomal disease caused by mutations in the ABCD1 gene. Childhood cerebral ALD (CCALD) is characterized by inflammatory demyelination, rapidly progressing, often fatal. Hematopoietic stem cell transplant only delays disease progression in patients with early-stage cerebral ALD. Based on emergency humanitarianism, this study aims to investigate the safety and efficacy of sirolimus in the treatment of patients with CCALD.

Methods

This was a prospective, single-center, one-arm clinical trial. We enrolled patients with CCALD, and all enrolled patients received sirolimus treatment for three months. Adverse events were monitored and recorded to evaluate the safety. The efficacy was evaluated using the neurologic function scale (NFS), Loes score, and white matter hyperintensities.

Results

A total of 12 patients were included and all presented with CCALD. Four patients dropped out and a total of eight patients in the advanced stage completed a 3-month follow-up. There were no serious adverse events, and the common adverse events were hypertonia and oral ulcers. After sirolimus treatment, three of the four patients with an initial NFS > 10 showed improvements in their clinical symptoms. Loes scores decreased by 0.5-1 point in two of eight patients and remained unchanged in one patient. Analysis of white matter hyperintensities revealed a significant decrease in signal intensity (n = 7, p = 0.0156).

Conclusions

Our study suggested that autophagy inducer sirolimus is safe for CCALD. Sirolimus did not improve clinical symptoms of patients with advanced CCALD significantly. Further study with larger sample size and longer follow-up is needed to confirm the drug efficacy.Clinical Trial registration: https://www.chictr.org.cn/historyversionpuben.aspx, identifier ChiCTR1900021288.

Clinical course and endocrine dysfunction in X-linked adrenoleukodystrophy: A case series

BACKGROUND AND PURPOSE

X-linked adrenoleukodystrophy (X-ALD) is a peroxisomal disorder affecting particularly the nervous tissue and adrenal cortex. Adrenomyeloneuropathy (AMN) is the most frequent phenotype, although adrenal insufficiency is usually the first manifestation in male patients. We set out to describe the clinical and biochemical features, together with the clinical course of X-ALD patients, focusing particularly on endocrine dysfunction.

PATIENTS AND METHODS

A retrospective study of 10 male X-ALD patients followed up at the Endocrinology Department. Epidemiologic data, phenotype evolution, endocrine and neurological findings and family history were analysed.

RESULTS

All the patients presented with adrenal insufficiency, 4 of them during adulthood, with a mean age of 19.6±17.1 years (6-64 years). Six patients had mineralocorticoid deficiency. At diagnosis, 8 patients had Addison-only phenotype and 2 AMN phenotype. In the course of follow-up (24.9±16.1 years), 4 patients developed AMN about 25.0±7.4 years after the initial diagnosis and 2 patients presented the cerebral adult form 11 and 17 years after the initial diagnosis. Testosterone levels were within the normal range in all patients. There were 7 families, and age of onset and clinical course were similar in 3 of them.

CONCLUSIONS

The presentation of X-ALD varied widely, 40% of the patients presented with adrenal insufficiency in adulthood, 60% had mineralocorticoid deficiency, and the onset and progression of neurological manifestations showed no pattern. Nevertheless, some similarities in the clinical course were found in some families. Our findings reinforce the need for screening for X-ALD at any age when approaching adrenal insufficiency and the importance of a multidisciplinary approach between endocrinologists and neurologists.

The genetic and phenotypic spectra of adult genetic leukoencephalopathies in a cohort of 309 patients

Genetic leukoencephalopathies (gLEs) are a highly heterogeneous group of rare genetic disorders. The spectrum of gLEs varies among patients of different ages. Distinct from the relatively more abundant studies of gLEs in children, only a few studies that explore the spectrum of adult gLEs have been published, and it should be noted that the majority of these excluded certain gLEs. Thus, to date, no large study has been designed and conducted to characterize the genetic and phenotypic spectra of gLEs in adult patients. We recruited a consecutive series of 309 adult patients clinically suspected of gLEs from Beijing Tiantan Hospital between January 2014 and December 2021. Whole-exome sequencing, mitochondrial DNA sequencing and repeat analysis of NOTCH2NLC, FMR1, DMPK and ZNF9 were performed for patients. We describe the genetic and phenotypic spectra of the set of patients with a genetically confirmed diagnosis and summarize their clinical and radiological characteristics. A total of 201 patients (65%) were genetically diagnosed, while 108 patients (35%) remained undiagnosed. The most frequent diseases were leukoencephalopathies related to NOTCH3 (25%), NOTCH2NLC (19%), ABCD1 (9%), CSF1R (7%) and HTRA1 (5%). Based on a previously proposed pathological classification, the gLEs in our cohort were divided into leukovasculopathies (35%), leuko-axonopathies (31%), myelin disorders (21%), microgliopathies (7%) and astrocytopathies (6%). Patients with NOTCH3 mutations accounted for 70% of the leukovasculopathies, followed by HTRA1 (13%) and COL4A1/2 (9%). The leuko-axonopathies contained the richest variety of associated genes, of which NOTCH2NLC comprised 62%. Among myelin disorders, demyelinating leukoencephalopathies (61%)-mainly adrenoleukodystrophy and Krabbe disease-accounted for the majority, while hypomyelinating leukoencephalopathies (2%) were rare. CSF1R was the only mutated gene detected in microgliopathy patients. Leukoencephalopathy with vanishing white matter disease due to mutations in EIF2B2-5 accounted for half of the astrocytopathies. We characterized the genetic and phenotypic spectra of adult gLEs in a large Chinese cohort. The most frequently mutated genes were NOTCH3, NOTCH2NLC, ABCD1, CSF1R and HTRA1.

Novel Therapeutic Approaches in Inherited Neuropathies: A Systematic Review

The management of inherited neuropathies relies mostly on the treatment of symptoms. In recent years, a better understanding of the pathogenic mechanisms that underlie neuropathies has allowed for the development of disease-modifying therapies. Here, we systematically review the therapies that have emerged in this field over the last five years. An updated list of diseases with peripheral neuropathy as a clinical feature was created based on panels of genes used clinically to diagnose inherited neuropathy. This list was extended by an analysis of published data by the authors and verified by two experts. A comprehensive search for studies of human patients suffering from one of the diseases in our list yielded 28 studies that assessed neuropathy as a primary or secondary outcome. Although the use of various scales and scoring systems made comparisons difficult, this analysis identified diseases associated with neuropathy for which approved therapies exist. An important finding is that the symptoms and/or biomarkers of neuropathies were assessed only in a minority of cases. Therefore, further investigation of treatment efficacy on neuropathies in future trials must employ objective, consistent methods such as wearable technologies, motor unit indexes, MRI or sonography imaging, or the use of blood biomarkers associated with consistent nerve conduction studies.

Structure and Mechanism of Human ABC Transporters

ABC transporters are essential for cellular physiology. Humans have 48 ABC genes organized into seven distinct families. Of these genes, 44 (in five distinct families) encode for membrane transporters, of which several are involved in drug resistance and disease pathways resulting from transporter dysfunction. Over the last decade, advances in structural biology have vastly expanded our mechanistic understanding of human ABC transporter function, revealing details of their molecular arrangement, regulation, and interactions, facilitated in large part by advances in cryo-EM that have rendered hitherto inaccessible targets amenable to high-resolution structural analysis. As a result, experimentally determined structures of multiple members of each of the five families of ABC transporters in humans are now available. Here we review this recent progress, highlighting the physiological relevance of human ABC transporters and mechanistic insights gleaned from their direct structure determination. We also discuss the impact and limitations of model systems and structure prediction methods in understanding human ABC transporters and discuss current challenges and future research directions.

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.

Cerebral X-linked Adrenoleukodystrophy Presenting As Enlarging Cavum Vergae Cyst: A Case Report

The cavum vergae cyst (CVC) is an uncommon brain malformation. Most patients with CVC are asymptomatic and do not require neurosurgical intervention. Separately, cerebral X-linked adrenoleukodystrophy (X-ALD) is one of the phenotypes of a genetic peroxisomal disorder that is seldom managed by neurosurgeons. We report an unusual case of cerebral X-ALD presenting as an enlarging CVC in a child, and discuss its nuances in corroboration with the literature. A previously well six-year-old male presented with confusion and fever. Urgent neuroimaging demonstrated a large CVC with resultant hydrocephalus. Of note, there were symmetrical areas of signal changes in the periventricular white matter bilaterally involving the corpus callosum, thalami, cerebral peduncles, midbrain, and pons in his MRI. Further investigations performed as part of his medical workup reported high plasma concentrations of very long-chain fatty acids (VLCFA). Put together, a diagnosis of cerebral X-ALD was confirmed. Initially, an external ventricular drain was inserted directly into the CVC under stereotaxy to decompress it. Subsequently, endoscopic fenestration of the CVC was performed as the definitive treatment. He recovered uneventfully from the neurosurgical interventions and proceeded for the treatment of his cerebral X-ALD. To our knowledge, this is the first report of cerebral X-ALD presenting as a CVC in a patient. This case adds to the limited literature for both rare conditions and highlights the importance of a multidisciplinary approach to management.

Severe Pressure Ulcers in Two Patients With Adrenoleukodystrophy

Adrenoleukodystrophy (ALD) is a rare X-linked disease that affects the metabolism of very long-chain fatty acids (VLCFAs), leading to cognitive deterioration, progressive spastic paraplegia, sensory disturbance, adrenocortical insufficiency, and bladder and bowel abnormalities. Although the symptoms of ALD correspond to the risk of developing pressure ulcers, a pressure ulcer has never been listed as a complication of ALD. We present two cases of ALD with severe pressure ulcers in the pelvic region and feet. The first case was a 27-year-old male patient with adolescent cerebral-type ALD who had pressure ulcers with bone exposure on the sacral and bilateral greater trochanter region. The second case was a 64-year-old male patient with adrenomyeloneuropathy (AMN) phenotype who had pressure ulcers on the sacral region and both feet. Both patients had VLCFA accumulation and a likely pathogenic variant in the ABCD1 gene, the causative gene of ALD. These cases indicate that ALD patients with immobility and incontinence have a higher risk of developing severe pressure ulcers, which requires the proactive identification of ALD patients and early multidisciplinary intervention for patients and their families to prevent the development of pressure ulcers.

Two Single Nucleotide Deletions in the ABCD1 Gene Causing Distinct Phenotypes of X-Linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is a rare inborn error of the peroxisomal metabolism caused by pathologic variants in the ATP-binding cassette transporter type D, member 1 (ABCD1) gene located on the X-chromosome. ABCD1 protein, also known as adrenoleukodystrophy protein, is responsible for transport of the very long chain fatty acids (VLCFA) from cytoplasm into the peroxisomes. Therefore, altered function or lack of the ABCD1 protein leads to accumulation of VLCFA in various tissues and blood plasma leading to either rapidly progressive leukodystrophy (cerebral ALD), progressive adrenomyeloneuropathy (AMN), or isolated primary adrenal insufficiency (Addison's disease). We report two distinct single nucleotide deletions in the ABCD1 gene, c.253delC [p.Arg85Glyfs*18] in exon 1, leading to both cerebral ALD and to AMN phenotype in one family, and c.1275delA [p.Phe426Leufs*15] in exon 4, leading to AMN and primary adrenal insufficiency in a second family. For the latter variant, we demonstrate reduced mRNA expression and a complete absence of the ABCD1 protein in PBMC. Distinct mRNA and protein expression in the index patient and heterozygous carriers does not associate with VLCFA concentration in plasma, which is in line with the absence of genotype-phenotype correlation in X-ALD.

Therapeutic Role of ELOVL in Neurological Diseases

Fatty acids play an important role in controlling the energy balance of mammals. De novo lipogenesis also generates a significant amount of lipids that are endogenously produced in addition to their ingestion. Fatty acid elongation beyond 16 carbons (palmitic acid), which can lead to the production of very long chain fatty acids (VLCFA), can be caused by the rate-limiting condensation process. Seven elongases, ELOVL1-7, have been identified in mammals and each has a unique substrate specificity. Researchers have recently developed a keen interest in the elongation of very long chain fatty acids protein 1 (ELOVL1) enzyme as a potential treatment for a variety of diseases. A number of neurological disorders directly or indirectly related to ELOVL1 involve the elongation of monounsaturated (C20:1 and C22:1) and saturated (C18:0-C26:0) acyl-CoAs. VLCFAs and ELOVL1 have a direct impact on the neurological disease. Other neurological symptoms such as ichthyotic keratoderma, spasticity, and hypomyelination have also been linked to the major enzyme (ELOVL1). Recently, ELOVL1 has also been heavily used to treat a number of diseases. The current review focuses on in-depth unique insights regarding the role of ELOVL1 as a therapeutic target and associated neurological disorders.

Computational insight into structural basis of human ELOVL1 inhibition

Very long-chain fatty acids (VLCFAs) play a direct role in the development of a neurological disorder, X-linked adrenoleukodystrophy (X-ALD). Since ELOVL1 catalyzes the rate-limiting step of the synthesis of VLCFAs, it has emerged as an attractive target for the treatment of X-ALD. Recently two potent inhibitors, compound 22 (C22) and compound 27 (C27) have been reported to specifically inhibit human ELOVL1 but their structural basis of inhibition has not been explored. In the present study, we have used a homology model of human ELOVL1 to deduce the binding site and binding modes of C22 and C27. We have employed computational approaches to characterize the binding of C22 and C27. Initially, binding of hexacosanoyl-CoA (C26:0-CoA) to ELOVL1 was modelled and further validated by molecular dynamics (MD) simulation. We observed that the fatty acid tail of C26: CoA protrudes from a unique opening located at the occluded end of ELOVL1. Structural comparison of ELOVL1 with the crystal structure of ELOVL7 revealed that the unique opening was not present in human ELOVL7. Combined blind and focused molecular docking approaches revealed that C22 and C27 exhibit favourable binding in the same unique opening. Further, MD simulations and free binding energy calculations confirmed that C22 and C27 maintain the favourable binding in the unique opening of ELOVL1. Overall, our findings suggest that selective human ELOVL1 inhibitors block the binding of long tails of VLCFAs near the occluded end of ELOVL1. Present study will be helpful in the discovery and design of novel, selective and potent inhibitors of human ELOVL1.

Clinical and biochemical footprints of inherited metabolic disorders. XI. Gastrointestinal symptoms

Inherited metabolic disorders presenting with gastrointestinal (GI) symptoms are characterized by the dysfunction of the esophagus, stomach, small and large intestines, and pancreas. We have summarized associations of signs and symptoms in 339 inherited metabolic diseases presenting with GI symptoms. Feeding difficulties represent the most common abnormality reported for IMDs with GI involvement (37%) followed by intestinal problems (30%), vomiting (22%), stomach and pancreas involvement (8% each), and esophagus involvement (4%). This represents the eleventh of a series of articles attempting to create and maintain a comprehensive list of clinical and metabolic differential diagnoses according to system involvement.

A case series of adrenoleukodystrophy in children conceived through in vitro fertilization with an egg donor

Objective

To report 3 cases of adrenoleukodystrophy (ALD) in children conceived by in vitro fertilization (IVF) and egg donation.

Design

A case report.

Patients

Patients aged 4-5 years old, evaluated by the University of Minnesota Leukodystrophy Center, who were diagnosed with ALD after being conceived by IVF with oocytes provided by the same donor.

Interventions

One patient received a hematopoietic stem cell transplant from a human leukocyte antigen-matched donor, and 1 patient received autologous lentiviral corrected hematopoietic cells. The disease state in 1 patient was unfortunately too advanced for effective treatment to be administered.

Main Outcome Measures

Progression of disease after diagnosis or treatment was observed by cerebral magnetic resonance imaging and monitoring the development or advancement of any cognitive, adaptive, and motor deficits.

Results

Patients who received a transplant for ALD successfully experienced little to no disease progression at least 6 months to 1 year after treatment.

Conclusions

These 3 cases of transmission of ALD through oocyte donation and IVF highlight the potential need to implement more comprehensive genetic screening of gamete donors to prevent the transfer of rare but severe genetic diseases through IVF. Further, these cases highlight limitations in carrier screening guidelines that limit reportable variants to pathogenic and likely pathogenic variants.

Neurocognitive and mental health impact of adrenoleukodystrophy across the lifespan: Insights for the era of newborn screening

X-linked adrenoleukodystrophy (ALD) is a rare inherited neurological disorder that poses considerable challenges for clinical management throughout the lifespan. Although males are generally more severely affected than females, the time course and presentation of clinical symptoms are otherwise difficult to predict. Opportunities to improve outcomes for individuals with ALD are rapidly expanding due to the introduction of newborn screening programs for this condition and an evolving treatment landscape. The aim of this comprehensive review is to synthesize current knowledge regarding the neurocognitive and mental health effects of ALD. This review provides investigators and clinicians with context to improve case conceptualization, inform prognostic counseling, and optimize neuropsychological and mental health care for patients and their families. Results highlight key predictive factors and brain-behavior relationships associated with the diverse manifestations of ALD. The review also discusses considerations for endpoints within clinical trials and identifies gaps to address in future research.