Adrenoleukodystrophy - neuroendocrine pathogenesis and redefinition of natural history

Imbalanced mitochondrial dynamics contributes to the pathogenesis of X-linked adrenoleukodystrophy

The peroxisomal disease adrenoleukodystrophy (X-ALD) is caused by loss of the transporter of very-long-chain fatty acids (VLCFAs), ABCD1. An excess of VLCFAs disrupts essential homeostatic functions crucial for axonal maintenance, including redox metabolism, glycolysis and mitochondrial respiration. As mitochondrial function and morphology are intertwined, we set out to investigate the role of mitochondrial dynamics in X-ALD models. Using quantitative 3D transmission electron microscopy, we revealed mitochondrial fragmentation in corticospinal axons in Abcd1- mice. In patient fibroblasts, an excess of VLCFAs triggers mitochondrial fragmentation through the redox-dependent phosphorylation of DRP1 (DRP1S616). The blockade of DRP1-driven fission by the peptide P110 effectively preserved mitochondrial morphology. Furthermore, mRNA inhibition of DRP1 not only prevented mitochondrial fragmentation but also protected axonal health in a Caenorhabditis elegans model of X-ALD, underscoring DRP1 as a potential therapeutic target. Elevated levels of circulating cell-free mtDNA in patients' CSF align this leukodystrophy with primary mitochondrial disorders. Our findings underscore the intricate interplay between peroxisomal dysfunction, mitochondrial dynamics and axonal integrity in X-ALD, shedding light on potential avenues for therapeutic intervention.

Four-dimensional Lipidomics Profiling in X-linked Adrenoleukodystrophy using Trapped Ion Mobility Mass Spectrometry

Lipids play pivotal roles in an extensive range of metabolic and physiological processes. In recent years, the convergence of trapped ion mobility (TIMS) and mass spectrometry (MS) has enabled 4D-lipidomics, a highly promising technology for comprehensive lipid analysis. 4D-lipidomics assesses lipid annotations across four distinct dimensions-retention time, collisional cross section, m/z (mass-to-charge ratio), and MS/MS spectra-providing a heightened level of confidence in lipid annotation. These advantages prove particularly valuable when investigating complex disorders involving lipid metabolism, such as adrenoleukodystrophy (ALD). ALD is characterized by the accumulation of very-long-chain fatty acids (VLCFA) due to pathogenic variants in the ABCD1 gene. A comprehensive 4D-lipidomics strategy of ALD fibroblasts demonstrated significant elevations of various lipids from multiple classes. This indicates that the changes observed in ALD are not confined to a single lipid class and likely impacts a broad spectrum of lipid-mediated physiological processes. Our findings highlight the incorporation of mainly saturated and monounsaturated VLCFA variants into a range of lipid classes, encompassing phosphatidylcholines, triacylglycerols, and cholesterol esters. These include ultra-long-chain fatty acids with a length of up to thirty carbon atoms. Lipid species containing C26:0, C26:1 were the most frequently detected VLCFA lipids in our study. Furthermore, we report a panel of 121 new candidate biomarkers in fibroblasts, exhibiting significant differentiation between controls and individuals with ALD. In summary, this study demonstrates the capabilities of a 4D-lipid profiling workflow in unraveling novel insights into the intricate lipid modifications associated with metabolic disorders like ALD.

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.

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.

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.

Increased neurotoxicity of high-density lipoprotein secreted from murine reactive astrocytes deficient in a peroxisomal very-long-chain fatty acid transporter Abcd1

X-linked adrenoleukodystrophy (X-ALD) is a genetic neurodegenerative disorder caused by pathogenic variants in ABCD1, resulting in the accumulation of very-long-chain fatty acids (VLCFAs) in tissues. The etiology of X-ALD is unclear. Activated astrocytes play a pathological role in X-ALD. Recently, reactive astrocytes have been shown to induce neuronal cell death via saturated lipids in high-density lipoprotein (HDL), although how HDL from reactive astrocytes exhibits neurotoxic effects has yet to be determined. In this study, we obtained astrocytes from wild-type and Abcd1-deficient mice. HDL was purified from the culture supernatant of astrocytes, and the effect of HDL on neurons was evaluated in vitro. To our knowledge, this study shows for the first time that HDL obtained from Abcd1-deficient reactive astrocytes induces a significantly higher level of lactate dehydrogenase (LDH) release, a marker of cell damage, from mouse primary cortical neurons as compared to HDL from wild-type reactive astrocytes. Notably, HDL from Abcd1-deficient astrocytes contained significantly high amounts of VLCFA-containing phosphatidylcholine (PC) and LysoPC. Activation of Abcd1-deficient astrocytes led to the production of HDL containing decreased amounts of PC with arachidonic acid in sn-2 acyl moieties and increased amounts of LysoPC, presumably through cytosolic phospholipase A2 α upregulation. These results suggest that compositional changes in PC and LysoPC in HDL, due to Abcd1 deficiency and astrocyte activation, may contribute to neuronal damage. Our findings provide novel insights into central nervous system pathology in X-ALD.

Plasma C24:0- and C26:0-lysophosphatidylcholines are reliable biomarkers for the diagnosis of peroxisomal β-oxidation disorders

The gold-standard diagnostic test for peroxisomal disorders (PDs) is plasma concentration analysis of very long-chain fatty acids (VLCFAs). However, this method's time-consuming nature and limitations in cases which present normal VLCFA levels necessitates alternative approaches. The analysis of C26:0-lysophosphatydylcholine (C26:0-LPC) in dried blood spot samples by tandem-mass spectrometry (MS/MS) has successfully been implemented in certain newborn screening programs to diagnose X-linked adrenoleukodystrophy (ALD). However, the diagnostic potential of very long-chain LPCs concentrations in plasma remains poorly understood. This study sought to evaluate the diagnostic performance of C26:0-LPC and other very long-chain LPCs, comparing them to VLCFA analysis in plasma. The study, which included 330 individuals affected by a peroxisomal β-oxidation deficiency and 407 control individuals, revealed that C26:0- and C24:0-LPC concentrations demonstrated the highest diagnostic accuracy (98.8% and 98.4%, respectively), outperforming VLCFA when C26:0/C22:0 and C24:0/C22:0 ratios were combined (98.1%). Combining C24:0- and C26:0-LPC gave the highest sensitivity (99.7%), with ALD females exhibiting notably higher sensitivity compared with the VLCFA ratio combination (98.7% vs. 93.5%, respectively). In contrast, C22:0-LPC exhibited suboptimal performance, primarily due to its low sensitivity (75%), but we identified a potential use to help distinguish between ALD and Zellweger spectrum disorders. In summary, MS/MS analysis of plasma C24:0- and C26:0-LPC concentrations represents a rapid and straightforward approach to diagnose PDs, demonstrating superior diagnostic accuracy, particularly in ALD females, compared with conventional VLCFA biomarkers. We strongly recommend integrating very-long chain LPC plasma analysis in the diagnostic evaluation of individuals suspected of having a PD.

Establishment and validation of a novel peroxisome-related gene prognostic risk model in kidney clear cell carcinoma

BACKGROUND

Kidney clear cell carcinoma (KIRC) is the most common subtype of renal cell carcinoma. Peroxisomes play a role in the regulation of tumorigenesis and cancer progression, yet the prognostic significance of peroxisome-related genes (PRGs) remains rarely studied. The study aimed to establish a novel prognostic risk model and identify potential biomarkers in KIRC.

METHODS

The significant prognostic PRGs were screened through differential and Cox regression analyses, and LASSO Cox regression analysis was performed to establish a prognostic risk model in the training cohort, which was validated internally in the testing and entire cohorts, and further assessed in the GSE22541 cohort. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed to explore the function and pathway differences between the high-risk and low-risk groups. The relationship between risk score and immune cell infiltration levels was evaluated in the CIBERSORT, ESTIMATE and TIMER databases. Finally, potential biomarkers were identified and validated from model genes, using immunohistochemistry.

RESULTS

Fourteen significant prognostic PRGs were identified using multiple analyses, and 9 genes (ABCD1, ACAD11, ACAT1, AGXT, DAO, EPHX2, FNDC5, HAO1, and HNGCLL1) were obtained to establish a prognostic model via LASSO Cox regression analysis. Combining the risk score with clinical factors to construct a nomogram, which provided support for personalized treatment protocols for KIRC patients. GO and KEGG analyses highlighted associations with substance metabolism, transport, and the PPAR signaling pathways. Tumor immune infiltration indicated immune suppression in the high-risk group, accompanied by higher tumor purity and the expression of 9 model genes was positively correlated with the level of immune cell infiltration. ACAT1 has superior prognostic capabilities in predicting the outcomes of KIRC patients.

CONCLUSIONS

The peroxisome-related prognostic risk model could better predict prognosis in KIRC patients.

Implication of Oxysterols and Phytosterols in Aging and Human Diseases

Cholesterol is easily oxidized and can be transformed into numerous oxidation products, among which oxysterols. Phytosterols are plant sterols related to cholesterol. Both oxysterols and phytosterols can have an impact on human health and diseases.Cholesterol is a member of the sterol family that plays essential roles in biological processes, including cell membrane stability and myelin formation. Cholesterol can be metabolized into several molecules including bile acids, hormones, and oxysterols. On the other hand, phytosterols are plant-derived compounds structurally related to cholesterol, which can also have an impact on human health. Here, we review the current knowledge about the role of oxysterols and phytosterols on human health and focus on the impact of their pathways on diseases of the central nervous system (CNS), autoimmune diseases, including inflammatory bowel diseases (IBD), vascular diseases, and cancer in both experimental models and human studies. We will first discuss the implications of oxysterols and then of phytosterols in different human diseases.

Immune response of BV-2 microglial cells is impacted by peroxisomal beta-oxidation

Microglia are crucial for brain homeostasis, and dysfunction of these cells is a key driver in most neurodegenerative diseases, including peroxisomal leukodystrophies. In X-linked adrenoleukodystrophy (X-ALD), a neuroinflammatory disorder, very long-chain fatty acid (VLCFA) accumulation due to impaired degradation within peroxisomes results in microglial defects, but the underlying mechanisms remain unclear. Using CRISPR/Cas9 gene editing of key genes in peroxisomal VLCFA breakdown (Abcd1, Abcd2, and Acox1), we recently established easily accessible microglial BV-2 cell models to study the impact of dysfunctional peroxisomal β-oxidation and revealed a disease-associated microglial-like signature in these cell lines. Transcriptomic analysis suggested consequences on the immune response. To clarify how impaired lipid degradation impacts the immune function of microglia, we here used RNA-sequencing and functional assays related to the immune response to compare wild-type and mutant BV-2 cell lines under basal conditions and upon pro-inflammatory lipopolysaccharide (LPS) activation. A majority of genes encoding proinflammatory cytokines, as well as genes involved in phagocytosis, antigen presentation, and co-stimulation of T lymphocytes, were found differentially overexpressed. The transcriptomic alterations were reflected by altered phagocytic capacity, inflammasome activation, increased release of inflammatory cytokines, including TNF, and upregulated response of T lymphocytes primed by mutant BV-2 cells presenting peptides. Together, the present study shows that peroxisomal β-oxidation defects resulting in lipid alterations, including VLCFA accumulation, directly reprogram the main cellular functions of microglia. The elucidation of this link between lipid metabolism and the immune response of microglia will help to better understand the pathogenesis of peroxisomal leukodystrophies.

Generation and characterization of induced pluripotent stem cell lines derived from skin fibroblasts of patients with adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is a rare peroxisome disease with phenotypic heterogeneity. There is a lack of suitable in vitro models to study its pathogenesis. We established two strains of iPSCs from skin fibroblasts of patients with childhood cerebral ALD and Addison's disease, respectively. CytoTune™2.0 Sendai reprogramming kit was used. The iPSC lines showed typical stem cell morphology, normal karyotype, and carrying ABCD1 variation. The iPSC lines express pluripotency markers, and have the capacity to differentiate into three germ layers. iPSCs can be used as an alternative cell source for ALD in vitro model to study its pathogenesis and therapeutic strategies.

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.

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.

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.

Inborn Errors of Metabolism with Ataxia: Current and Future Treatment Options

A number of hereditary ataxias are caused by inborn errors of metabolism (IEM), most of which are highly heterogeneous in their clinical presentation. Prompt diagnosis is important because disease-specific therapies may be available. In this review, we offer a comprehensive overview of metabolic ataxias summarized by disease, highlighting novel clinical trials and emerging therapies with a particular emphasis on first-in-human gene therapies. We present disease-specific treatments if they exist and review the current evidence for symptomatic treatments of these highly heterogeneous diseases (where cerebellar ataxia is part of their phenotype) that aim to improve the disease burden and enhance quality of life. In general, a multimodal and holistic approach to the treatment of cerebellar ataxia, irrespective of etiology, is necessary to offer the best medical care. Physical therapy and speech and occupational therapy are obligatory. Genetic counseling is essential for making informed decisions about family planning.

VUS: Variant of uncertain significance or very unclear situation?

The advancements in population screening, including newborn screening, enables the identification of disease-causing variants and timely initiation of treatment. However, screening may also identify mild variants, non-disease variants, and variants of uncertain significance (VUS). The identification of a VUS poses a challenge in terms of diagnostic uncertainty and confusion. X-linked adrenoleukodystrophy (ALD) serves as an illustrative example of this complex issue. ALD is a monogenic neurometabolic disease with a complex clinical presentation and a lack of predictive tests for clinical severity. Despite the success of ALD newborn screening, a significant proportion (62%) of missense variants identified through newborn screening exhibit uncertainty regarding their pathogenicity. Resolving this issue requires ongoing efforts to accurately classify variants and refine screening protocols. While it is undisputable that ALD newborn screening greatly benefits boys with the disease, the identification of VUS underscores the need for continuous research and collaboration in improving screening practices.

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.

Acute Mania and Psychosis in the Context of Primary Adrenal Insufficiency: A Systematic Review of the Literature

BACKGROUND

Given the sparse nature of acute mania or psychosis in primary adrenal insufficiency (PAI), physicians may not be aware of the association of these two entities.

OBJECTIVE

To conduct a systematic review of the literature for the purpose of identifying all studies reporting mania and/or psychosis in individuals with PAI.

METHOD

We conducted a systematic review according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the PubMed, Embase, and Web of Science databases from June 22, 1970 to June 22, 2021, for the purpose of identifying all studies reporting instances of mania or psychosis associated with PAI.

RESULTS

We identified nine case reports featuring nine patients (M age = 43.3 years, male = 44.4%) over eight countries that fit our inclusion/exclusion criteria. Eight (89%) of the patients had experienced psychosis. Manic and/or psychotic symptom resolution was achieved in 100% of the cases, of which steroid replacement therapy was efficacious in seven (78%) cases and was sufficient in six (67%).

CONCLUSION

Acute mania and psychosis in the context of PAI is a very rare presentation of an already uncommon disease. Resolution of acute psychiatric change is reliably achieved with the correction of underlying adrenal insufficiency.

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.

Growth alterations in rare forms of primary adrenal insufficiency: a neglected issue in paediatric endocrinology

Primary adrenal insufficiency (PAI) is an endocrine disorder characterized by direct adrenal failure^, with consequent glucocorticoid, and eventually mineralocorticoid, deficiency. In children, the main cause of PAI is congenital adrenal hyperplasia (CAH), due to a loss of function of adrenal steroidogenic enzymes, but also rarer forms, including autoimmune polyglandular syndrome, adrenoleucodistrophy, adrenal hypoplasia congenita, familial glucocorticoid deficiency, and Allgrove's Syndrome, may be observed. In PAI children, growth alterations represent a major issue, as both inadequate and excessive glucocorticoid replacement treatment may lead to reduced growth rate and adult height impairment. However, growth abnormalities are poorly studied in rare forms of paediatric PAI, and specific studies on growth rate in these children are currently lacking. In the present review, the currently available evidence on growth alterations in children with rare PAI forms will be summarized, with a major focus on comorbidities with a potential impact on patients' growth rate.

Self-reported quality of life in symptomatic and asymptomatic women with X-linked adrenoleukodystrophy

BACKGROUND

Up to 80% of women with X-linked adrenoleukodystrophy (X-ALD) develop symptoms of myelopathy and peripheral neuropathy during their lifetime. The study's objective was to compare symptomatic versus asymptomatic women with X-ALD regarding their physical and mental well-being and quality of life.

METHODS

Data were obtained from a prospective, international, cross-sectional cohort study of women with X-ALD recruited both clinically and population based. Symptoms, quality of life, and physical and mental co-morbidities were assessed by questionnaires. Women were considered symptomatic if they reported any sign of myelopathy or peripheral neuropathy. Group differences between symptomatic versus asymptomatic women and between age groups were examined using χ² tests for categorical and independent sample t tests or analysis of variance for continuous variables.

RESULTS

Complete data were available from N = 180 women (mean age: 51.2 ± 13.6 years, range: 18-85), of whom 71.7% were classified as symptomatic, with prevalence increasing with age. Symptomatic versus asymptomatic women reported poorer physical and mental health, with 26.4% meeting the criteria for a clinical depression, 73.6% reporting chronic pain, 80.6% sleeping disturbances, 38.2% sexual dysfunction, and 47.3% restless legs syndrome. Large group differences were found on the physical health, but not on the mental health component of quality of life, where symptomatic women only differed when controlling for having a boy affected by X-ALD (small effect) and treatment frequency (medium effect).

CONCLUSIONS

Symptomatic women with X-ALD present with physical and psychological co-morbidities significantly reducing individuals' quality of life. The findings emphasize the need to develop new multi-disciplinary treatment options tailored to women's specific needs.

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.

Peroxisomes attenuate cytotoxicity of very long-chain fatty acids

One of the major functions of peroxisomes in mammals is oxidation of very long-chain fatty acids (VLCFAs). Genetic defects in peroxisomal β-oxidation result in the accumulation of VLCFAs and lead to a variety of health problems, such as demyelination of nervous tissues. However, the mechanisms by which VLCFAs cause tissue degeneration have not been fully elucidated. Recently, we found that the addition of small amounts of isopropanol can enhance the solubility of saturated VLCFAs in an aqueous medium. In this study, we characterized the biological effect of extracellular VLCFAs in peroxisome-deficient Chinese hamster ovary (CHO) cells, neural crest-derived pheochromocytoma cells (PC12), and immortalized adult Fischer rat Schwann cells (IFRS1) using this solubilizing technique. C20:0 FA was the most toxic of the C16-C26 FAs tested in all cells. The basis of the toxicity of C20:0 FA was apoptosis and was observed at 5 μM and 30 μM in peroxisome-deficient and wild-type CHO cells, respectively. The sensitivity of wild-type CHO cells to cytotoxic C20:0 FA was enhanced in the presence of a peroxisomal β-oxidation inhibitor. Further, a positive correlation was evident between cell toxicity and the extent of intracellular accumulation of toxic FA. These results suggest that peroxisomes are pivotal in the detoxification of apoptotic VLCFAs by preventing their accumulation.

Sex-specific newborn screening for X-linked adrenoleukodystrophy

Males with X-linked adrenoleukodystrophy (ALD) are at high risk for developing adrenal insufficiency and/or progressive leukodystrophy (cerebral ALD) at an early age. Pathogenic variants in ABCD1 result in elevated levels of very long-chain fatty acids (VLCFA), including C26:0-lysophosphatidylcholine (C26:0-LPC). Newborn screening for ALD enables prospective monitoring and timely therapeutic intervention, thereby preventing irreversible damage and saving lives. The Dutch Health Council recommended to screen only male newborns for ALD without identifying untreatable conditions associated with elevated C26:0-LPC, like Zellweger spectrum disorders and single peroxisomal enzyme defects. Here, we present the results of the SCAN (Screening for ALD in the Netherlands) study which is the first sex-specific newborn screening program worldwide. Males with ALD are identified based on elevated C26:0-LPC levels, the presence of one X-chromosome and a variant in ABCD1, in heel prick dried bloodspots. Screening of 71 208 newborns resulted in the identification of four boys with ALD who, following referral to the pediatric neurologist and confirmation of the diagnosis, enrolled in a long-term follow-up program. The results of this pilot show the feasibility of employing a boys-only screening algorithm that identifies males with ALD without identifying untreatable conditions. This approach will be of interest to countries that are considering ALD newborn screening but are reluctant to identify girls with ALD because for girls there is no direct health benefit. We also analyzed whether gestational age, sex, birth weight and age at heel prick blood sampling affect C26:0-LPC concentrations and demonstrate that these covariates have a minimal effect.

Peroxisomal defects in microglial cells induce a disease-associated microglial signature

Microglial cells ensure essential roles in brain homeostasis. In pathological condition, microglia adopt a common signature, called disease-associated microglial (DAM) signature, characterized by the loss of homeostatic genes and the induction of disease-associated genes. In X-linked adrenoleukodystrophy (X-ALD), the most common peroxisomal disease, microglial defect has been shown to precede myelin degradation and may actively contribute to the neurodegenerative process. We previously established BV-2 microglial cell models bearing mutations in peroxisomal genes that recapitulate some of the hallmarks of the peroxisomal β-oxidation defects such as very long-chain fatty acid (VLCFA) accumulation. In these cell lines, we used RNA-sequencing and identified large-scale reprogramming for genes involved in lipid metabolism, immune response, cell signaling, lysosome and autophagy, as well as a DAM-like signature. We highlighted cholesterol accumulation in plasma membranes and observed autophagy patterns in the cell mutants. We confirmed the upregulation or downregulation at the protein level for a few selected genes that mostly corroborated our observations and clearly demonstrated increased expression and secretion of DAM proteins in the BV-2 mutant cells. In conclusion, the peroxisomal defects in microglial cells not only impact on VLCFA metabolism but also force microglial cells to adopt a pathological phenotype likely representing a key contributor to the pathogenesis of peroxisomal disorders.

The physiological functions of human peroxisomes

Peroxisomes are subcellular organelles that play a central role in human physiology by catalyzing a range of unique metabolic functions. The importance of peroxisomes for human health is exemplified by the existence of a group of usually severe diseases caused by an impairment in one or more peroxisomal functions. Among others these include the Zellweger spectrum disorders, X-linked adrenoleukodystrophy, and Refsum disease. To fulfill their role in metabolism, peroxisomes require continued interaction with other subcellular organelles including lipid droplets, lysosomes, the endoplasmic reticulum, and mitochondria. In recent years it has become clear that the metabolic alliance between peroxisomes and other organelles requires the active participation of tethering proteins to bring the organelles physically closer together, thereby achieving efficient transfer of metabolites. This review intends to describe the current state of knowledge about the metabolic role of peroxisomes in humans, with particular emphasis on the metabolic partnership between peroxisomes and other organelles and the consequences of genetic defects in these processes. We also describe the biogenesis of peroxisomes and the consequences of the multiple genetic defects therein. In addition, we discuss the functional role of peroxisomes in different organs and tissues and include relevant information derived from model systems, notably peroxisomal mouse models. Finally, we pay particular attention to a hitherto underrated role of peroxisomes in viral infections.

Antioxidant Response in Human X-Linked Adrenoleukodystrophy Fibroblasts

Redox imbalance, mitochondrial dysfunction, and inflammation play a major role in the pathophysiology of X-linked adrenoleukodystrophy (X-ALD), an inherited neurodegenerative disease caused by mutations in the ABCD1 gene, encoding the protein responsible for peroxisomal import and degradation of very long chain fatty acids (VLCFAs). Therefore, VLCFAs accumulate in tissues and plasma, constituting a pathognomonic biomarker for diagnosis. However, the precise role of VLCFA accumulation on the diverse clinical phenotypes of X-ALD and the pathogenic link between VLCFAs and oxidative stress remain currently unclear. This study proposes ferroptosis as a crucial contributor to the disease development and progression. The expression profiles of "GPX4-glutathione" and "NQO1-CoQ₁₀" ferroptosis pathways have been analyzed in fibroblasts of one patient with AMN, the late onset and slowly progressive form of X-ALD, and in two patients with cALD, the cerebral inflammatory demyelinating form of early childhood. Furthermore, as no effective treatments are currently available, especially for the rapidly progressing form of X-ALD (cALD), the efficacy of NAC treatment has also been evaluated to open the way toward novel combined therapies. Our findings demonstrate that lipid peroxides accumulate in X-ALD fibroblasts and ferroptosis-counteracting enzymes are dysregulated, highlighting a different antioxidant response in patients with AMN and cALD.

Hypogonadism in Males With Genetic Neurodevelopmental Syndromes

Genetic syndromes that affect the nervous system may also disrupt testicular function, and the mechanisms for these effects may be interrelated. Most often neurological signs and symptoms predominate and hypogonadism remains undetected and untreated, while in other cases, a thorough evaluation of a hypogonadal male reveals previously unrecognized ataxia, movement disorder, muscle weakness, tremor, or seizures, leading to a syndromic diagnosis. Androgen deficiency in patients with neurological diseases may aggravate muscle weakness and fatigue and predispose patients to osteoporosis and obesity. The purpose of this mini review is to provide a current understanding of the clinical, biochemical, histologic, and genetic features of syndromes in which male hypogonadism and neurological dysfunction may coexist and may be encountered by the clinical endocrinologist.

Identifying transdiagnostic biological subtypes across schizophrenia, bipolar disorder, and major depressive disorder based on lipidomics profiles

Emerging evidence has demonstrated overlapping biological abnormalities underlying schizophrenia (SCZ), bipolar disorder (BP), and major depressive disorder (MDD); these overlapping abnormalities help explain the high heterogeneity and the similarity of patients within and among diagnostic categories. This study aimed to identify transdiagnostic subtypes of these psychiatric disorders based on lipidomics abnormalities. We performed discriminant analysis to identify lipids that classified patients (N = 349, 112 with SCZ, 132 with BP, and 105 with MDD) and healthy controls (N = 198). Ten lipids that mainly regulate energy metabolism, inflammation, oxidative stress, and fatty acylation of proteins were identified. We found two subtypes (named Cluster 1 and Cluster 2 subtypes) across patients with SCZ, BP, and MDD by consensus clustering analysis based on the above 10 lipids. The distribution of clinical diagnosis, functional impairment measured by Global Assessment of Functioning (GAF) scales, and brain white matter abnormalities measured by fractional anisotropy (FA) and radial diffusivity (RD) differed in the two subtypes. Patients within the Cluster 2 subtype were mainly SCZ and BP patients and featured significantly elevated RD along the genu of corpus callosum (GCC) region and lower GAF scores than patients within the Cluster 1 subtype. The SCZ and BP patients within the Cluster 2 subtype shared similar biological patterns; that is, these patients had comparable brain white matter abnormalities and functional impairment, which is consistent with previous studies. Our findings indicate that peripheral lipid abnormalities might help identify homogeneous transdiagnostic subtypes across psychiatric disorders.

Parents’ views on accepting, declining, and expanding newborn bloodspot screening

Introduction

The goal of newborn bloodspot screening (NBS) is the early detection of treatable disorders in newborns to offer early intervention. Worldwide, the number of conditions screened for is expanding, which might affect public acceptance. In the Netherlands, participation is high (>99%), but little is known about how parents perceive NBS. This study assessed parents’ views on accepting, declining and expanding NBS.

Methods

A total of 804 of 6051 (13%) invited parents who participated in NBS in the Netherlands during the last two weeks of December 2019, and 48 of 1162 (4%) invited parents who declined participation in NBS in 2019 and 2020, completed a questionnaire.

Results

The most important reason for parents to participate in NBS was to prevent health complaints, whereas the most important reason to decline NBS was parents’ viewpoint on life and the belief that the heel prick would be painful for the child. Compared to NBS participants, respondents who declined NBS were more actively religious, considered alternative medicine or lifestyle more important, were less inclined to vaccinate their child for infectious diseases, and reported more doubt about NBS participation (all differences p < .001). Informed choice was lower among respondents who declined NBS (44%) compared to participants in NBS (83%, p < .001), mostly due to insufficient knowledge. Of the NBS participants, 95% were positive about NBS expansion. Most NBS participants agreed to include conditions that could unintentionally reveal a diagnosis in the mother instead of the child (86%) or a condition that may not cause symptoms until later in the child’s life (84%).

Conclusion

Most participants made an informed decision to participate in NBS and are positive about screening for more conditions. Insights into parents’ views on (non-)participation and expansion of NBS can help to ensure that NBS suits the population needs while safeguarding ethical principles for screening.

ABCD1 Gene Mutations: Mechanisms and Management of Adrenomyeloneuropathy

Pathogenic variants in the ABCD1 gene on the X chromosome may result in widely heterogenous phenotypes, including adrenomyeloneuropathy (AMN). Affected males typically present in their third or fourth decade of life with progressive lower limb weakness and spasticity, and may develop signs and symptoms of adrenal insufficiency and/or cerebral demyelination. Heterozygous females may be asymptomatic, but may develop a later-onset and more slowly progressive spastic paraparesis. In this review, we describe the clinical presentation of AMN, as well as its diagnosis and management. The role of rehabilitative therapies and options for management of spasticity are highlighted.

Beneficial Effects of the Direct AMP-Kinase Activator PXL770 in In Vitro and In Vivo Models of X-Linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (ALD) is a severe orphan disease caused by mutations in the peroxisomal ABCD1 transporter gene, leading to toxic accumulation of Very Long-Chain Fatty Acids (VLCFA - in particular C26:0) resulting in inflammation, mitochondrial dysfunction and demyelination. AMP-activated protein kinase (AMPK) is downregulated in ALD, and its activation is implicated as a therapeutic target. PXL770 is the first direct allosteric AMPK activator with established clinical efficacy and tolerability. Methods: We investigated its effects in ALD patient-derived fibroblasts/lymphocytes and Abcd1 KO mouse glial cells. Readouts included VLCFA levels, mitochondrial function and mRNA levels of proinflammatory genes and compensatory transporters (ABCD2-3). After PXL770 treatment in Abcd1 KO mice, we assessed VLCFA levels in tissues, sciatic nerve axonal morphology by electronic microscopy and locomotor function by open-field/balance-beam tests. Results: In patients' cells and Abcd1 KO glial cells, PXL770 substantially decreased C26:0 levels (by ∼90%), improved mitochondrial respiration, reduced expression of multiple inflammatory genes and induced expression of ABCD2-3 In Abcd1 KO mice, PXL770 treatment normalized VLCFA in plasma and significantly reduced elevated levels in brain (-25%) and spinal cord (-32%) versus untreated (P < 0.001). Abnormal sciatic nerve axonal morphology was also improved along with amelioration of locomotor function. Conclusion: Direct AMPK activation exerts beneficial effects on several hallmarks of pathology in multiple ALD models in vitro and in vivo, supporting clinical development of PXL770 for this disease. Further studies would be needed to overcome limitations including small sample size for some parameters, lack of additional in vivo biomarkers and incomplete pharmacokinetic characterization. SIGNIFICANCE STATEMENT: Adrenoleukodystrophy is a rare and debilitating condition with no approved therapies, caused by accumulation of very long-chain fatty acids. AMPK is downregulated in the disease and has been implicated as a potential therapeutic target. PXL770 is a novel clinical stage direct AMPK activator. In these studies, we used PXL770 to achieve preclinical validation of direct AMPK activation for this disease - based on correction of key biochemical and functional readouts in vitro and in vivo, thus supporting clinical development.

Activating cannabinoid receptor 2 preserves axonal health through GSK-3β/NRF2 axis in adrenoleukodystrophy

Aberrant endocannabinoid signaling accompanies several neurodegenerative disorders, including multiple sclerosis. Here, we report altered endocannabinoid signaling in X-linked adrenoleukodystrophy (X-ALD), a rare neurometabolic demyelinating syndrome caused by malfunction of the peroxisomal ABCD1 transporter, resulting in the accumulation of very long-chain fatty acids (VLCFAs). We found abnormal levels of cannabinoid receptor 2 (CB2r) and related endocannabinoid enzymes in the brain and peripheral blood mononuclear cells (PBMCs) of X-ALD patients and in the spinal cord of a murine model of X-ALD. Preclinical treatment with a selective agonist of CB2r (JWH133) halted axonal degeneration and associated locomotor deficits, along with normalization of microgliosis. Moreover, the drug improved the main metabolic disturbances underlying this model, particularly in redox and lipid homeostatic pathways, including increased lipid droplets in motor neurons, through the modulation of the GSK-3β/NRF2 axis. JWH133 inhibited Reactive Oxygen Species elicited by excess VLCFAs in primary microglial cultures of Abcd1-null mice. Furthermore, we uncovered intertwined redox and CB2r signaling in the murine spinal cords and in patient PBMC samples obtained from a phase II clinical trial with antioxidants (NCT01495260). These findings highlight CB2r signaling as a potential therapeutic target for X-ALD and perhaps other neurodegenerative disorders that present with dysregulated redox and lipid homeostasis.

Ocular findings and genomics of X-linked recessive disorders: A review

Advent of new sequencing technologies and modern diagnostic procedures has opened the door for a deeper understanding of disorders about which little was known previously. Discovery of novel genes, new genetic variants in previously known genes and better techniques of functional validation has immensely contributed to unraveling the molecular basis of genetic disorders. Availability of knockout animal models like the zebrafish and gene editing tools like CRISPR-Cas9 has elucidated the function of many new genes and helped us to better understand the functional consequences of various gene defects. This has also led to better diagnosis and therapeutic interventions. In this context, a good body of research work has been done on X-linked recessive disorders with ocular findings. This review will focus on ocular and genetic findings of these rare disorders. To our knowledge, this is the first comprehensive review encompassing ocular and genomic spectrum of X-linked recessive disorders.

Glial Cells and Brain Diseases: Inflammasomes as Relevant Pathological Entities

Inflammation mediated by the innate immune system is a physiopathological response to diverse detrimental circumstances such as microbe infections or tissular damage. The molecular events that underlie this response involve the assembly of multiprotein complexes known as inflammasomes. These assemblages are essentially formed by a stressor-sensing protein, an adapter protein and a non-apoptotic caspase (1 or 11). The coordinated aggregation of these components mediates the processing and release of pro-inflammatory interleukins (IL-β and IL-18) and cellular death by pyroptosis induction. The inflammatory response is essential for the defense of the organism; for example, it triggers tissue repair and the destruction of pathogen microbe infections. However, when inflammation is activated chronically, it promotes diverse pathologies in the lung, liver, brain and other organs. The nervous system is one of the main tissues where the inflammatory process has been characterized, and its implications in health and disease are starting to be understood. Thus, the regulation of inflammasomes in specific cellular types of the central nervous system needs to be thoroughly understood to innovate treatments for diverse pathologies. In this review, the presence and participation of inflammasomes in pathological conditions in different types of glial cells will be discussed.

Peroxisome Metabolism Contributes to PIEZO2-Mediated Mechanical Allodynia

Mutations in the peroxisomal half-transporter ABCD1 cause X-linked adrenoleukodystrophy, resulting in elevated very long-chain fatty acids (VLCFA), progressive neurodegeneration and an associated pain syndrome that is poorly understood. In the nervous system of mice, we found ABCD1 expression to be highest in dorsal root ganglia (DRG), with satellite glial cells (SGCs) displaying higher expression than neurons. We subsequently examined sensory behavior and DRG pathophysiology in mice deficient in ABCD1 compared to wild-type mice. Beginning at 8 months of age, Abcd1-/y mice developed persistent mechanical allodynia. DRG had a greater number of IB4-positive nociceptive neurons expressing PIEZO2, the mechanosensitive ion channel. Blocking PIEZO2 partially rescued the mechanical allodynia. Beyond affecting neurons, ABCD1 deficiency impacted SGCs, as demonstrated by high levels of VLCFA, increased glial fibrillary acidic protein (GFAP), as well as genes disrupting neuron-SGC connectivity. These findings suggest that lack of the peroxisomal half-transporter ABCD1 leads to PIEZO2-mediated mechanical allodynia as well as SGC dysfunction. Given the known supportive role of SGCs to neurons, this elucidates a novel mechanism underlying pain in X-linked adrenoleukodystrophy.

Primary Adrenal Insufficiency in a Boy with Type I Diabetes: The Importance of Considering X-linked Adrenoleukodystrophy

Primary adrenal insufficiency (PAI) is often the first clinical sign of X-linked adrenoleukodystrophy (X-ALD), a rare genetic disorder that can present with various clinical phenotypes. A subset of boys with X-ALD develop cerebral ALD (cALD), characterized by progressive central demyelination, neurocognitive decline, and ultimately death. Timely intervention with hematopoietic cell transplant (HCT) can be a life-saving therapy by stopping progression of cerebral disease. We report the case of an 11-year-old boy with type 1 diabetes mellitus who presented with PAI, growth delay, and symptoms of attention deficit hyperactivity disorder. Given his history of T1DM, his PAI was presumed to be autoimmune and he was started on hydrocortisone and fludrocortisone. Eleven months later brain magnetic resonance imaging revealed white matter hyperintensity consistent with advanced cALD. The degree of disease progression at the time of diagnosis rendered the patient ineligible for transplant and he has continued to experience progressive neurologic decline. Initial symptoms of cALD are often subtle but should not be overlooked, as early identification of X-ALD is critical to allow early intervention with lifesaving HCT. PAI typically presents prior to the onset of neurologic symptoms. All boys who present with PAI should undergo workup for X-ALD with plasma very long chain fatty acid testing, even in the setting of underlying autoimmune disease.

The Role of Oxidative Stress and Inflammation in X-Link Adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is an inherited disease caused by a mutation in the ABCD1 gene encoding a peroxisomal transmembrane protein. It is characterized by the accumulation of very-long-chain fatty acids (VLCFAs) in body fluids and tissues, leading to progressive demyelination and adrenal insufficiency. ALD has various phenotypes, among which the most common and severe is childhood cerebral adrenoleukodystrophy (CCALD). The pathophysiological mechanisms of ALD remain unclear, but some in vitro/in vivo research showed that VLCFA could induce oxidative stress and inflammation, leading to damage. In addition, the evidence that oxidative stress and inflammation are increased in patients with X-ALD also proves that it is a potential mechanism of brain and adrenal damage. Therefore, normalizing the redox balance becomes a critical therapeutic target. This study focuses on the possible predictors of the severity and progression of X-ALD, the potential mechanisms of pathogenesis, and the promising targeted drugs involved in oxidative stress and inflammation.

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.

The clinical spectrum of X-linked adrenoleukodystrophy: from Addison's-only in men to middle-age neurologic manifestations in women

X-linked adrenoleukodystrophy (X-ALD) is caused by a mutation in the ABCD1 gene which encodes for a peroxisomal very long-chain fatty acid (VLCFA) transporter. Clinically, X-ALD can present a wide range of phenotypes, from slowly progressive myelopathy to rapid demyelination of brain white matter (cerebral X-ALD-CALD). Adrenocortical insufficiency (AI) occurs mainly in the pediatric age group, and it can be the first manifestation of the disease. Female carriers may also develop manifestations of myelopathy, but later in life. We present two cases of patients who show the heterogeneous clinical manifestations of X-ALD. Case 1 was a man with AI diagnosed at 6 years old and with the first manifestations of myelopathy at 44 years old, which led to the diagnosis of X-ALD. At 47 years, he developed rapidly progressive CALD. Case 2 was a woman with progressive spastic gait disturbance that started at 49 years old. The diagnosis of X-ALD was confirmed at 54 years old after the discovery of a family history of the disease. Mild progression of the neurologic manifestations was noted, but with no signs of AI nor CALD. She is currently 60 years old and under surveillance. We review the current knowledge on X-ALD as concerns its genetic and pathophysiological mechanisms, clinical presentations, diagnosis, treatment, and follow-up. This condition is a real diagnostic challenge. The early detection of AI and CALD, potentially life-threatening complications in men, is very difficult. The surveillance of these complications in female patients still raises controversy.

Structure and Function of the ABCD1 Variant Database: 20 Years, 940 Pathogenic Variants, and 3400 Cases of Adrenoleukodystrophy

The progressive neurometabolic disorder X-linked adrenoleukodystrophy (ALD) is caused by pathogenic variants in the ABCD1 gene, which encodes the peroxisomal ATP-binding transporter for very-long-chain fatty acids. The clinical spectrum of ALD includes adrenal insufficiency, myelopathy, and/or leukodystrophy. A complicating factor in disease management is the absence of a genotype–phenotype correlation in ALD. Since 1999, most ABCD1 (likely) pathogenic and benign variants have been reported in the ABCD1 Variant Database. In 2017, following the expansion of ALD newborn screening, the database was rebuilt. To add an additional level of confidence with respect to pathogenicity, for each variant, it now also reports the number of cases identified and, where available, experimental data supporting the pathogenicity of the variant. The website also provides information on a number of ALD-related topics in several languages. Here, we provide an updated analysis of the known variants in ABCD1. The order of pathogenic variant frequency, overall clustering of disease-causing variants in exons 1–2 (transmembrane domain spanning region) and 6–9 (ATP-binding domain), and the most commonly reported pathogenic variant p.Gln472Argfs*83 in exon 5 are consistent with the initial reports of the mutation database. Novel insights include nonrandom clustering of high-density missense variant hotspots within exons 1, 2, 6, 8, and 9. Perhaps more importantly, we illustrate the importance of collaboration and utility of the database as a scientific, clinical, and ALD-community-wide resource.

In vivo gene editing via homology-independent targeted integration for adrenoleukodystrophy treatment

Adrenoleukodystrophy (ALD) is caused by various pathogenic mutations in the X-linked ABCD1 gene, which lead to metabolically abnormal accumulations of very long-chain fatty acids in many organs. However, curative treatment of ALD has not yet been achieved. To treat ALD, we applied two different gene-editing strategies, base editing and homology-independent targeted integration (HITI), in ALD patient-derived fibroblasts. Next, we performed in vivo HITI-mediated gene editing using AAV9 vectors delivered via intravenous administration in the ALD model mice. We found that the ABCD1 mRNA level was significantly increased in HITI-treated mice, and the plasma levels of C24:0-LysoPC (lysophosphatidylcholine) and C26:0-LysoPC, sensitive diagnostic markers for ALD, were significantly reduced. These results suggest that HITI-mediated mutant gene rescue could be a promising therapeutic strategy for human ALD treatment.

Identification of Two Novel Mutations of ABCD1 Gene in Pedigrees with X-Linked Adrenoleukodystrophy and Review of the Literature

BACKGROUND

X-linked adrenoleukodystrophy (ALD) is an inherited peroxisomal metabolism disorder, resulting from the loss-of-function mutation of ATP-binding cassette protein subfamily D1 (ABCD1) gene. The dysfunction of ALD protein, a peroxisomal ATP-binding cassette transporter, results in the excessive saturated very long-chain fatty acids (VLCFAs) accumulation in organs including the brain, spine, and adrenal cortex. X-ALD is characterized as the childhood, adolescent, adult cerebral ALD, adrenomyeloneuropathy (AMN), adrenal insufficiency, and asymptomatic phenotypes, exhibiting a high variety of clinical neurological manifestations with or without adrenocortical insufficiency.

RESULTS

In this study, we reported two cases of X-ALD, which were first diagnosed as adrenal insufficiency (Addison's disease) and treated with adrenocortical supplement. However, both of the cases progressed as neurological symptoms and signs after decades. Elevated VLCFAs level, brain MRI scan, and genetic analysis confirmed final diagnosis. In addition, we identified two novel mutations of ABCD1 gene, NM_000033.3 (ABCD1): c.874_876delGAG (p.Glu292del) and NM_000033.3 (ABCD1): c.96_97delCT (p.Tyr33Profs∗161), in exon 1 of ABCD1 gene. Sanger sequencing confirmed that the proband's mother of the first case was heterozygous carrying the same variant. Adrenal insufficiency-only type is very rare; however, it may be the starting performance of X-ALD. In addition, we summarized reported mutation sites and clinical manifestations to investigate the correlationship of phenotype-genotype of X-ALD.

CONCLUSIONS

The early warning manifestations should be noticed, and the probability of X-ALD should be considered. This report could be beneficial for the early diagnosis and genetic counseling for patients with X-ALD.