Search Results (58)

X-linked adrenoleukodystrophy (X-ALD) is a monogenic progressive neurodegenerative disorder, being simultaneously a systemic metabolic disease and demonstrating severe neurological manifestations with effects to the brain and spinal cord. The objective of the current review is to provide a detailed approach to adeno-associated virus (AAV)-based gene therapy for neurological manifestations of X-ALD. The development of a successful AAV-mediated gene therapy hinges on its ability to deliver ABCD1 cDNA effectively to the relevant organs and cell types, induce therapeutic levels of protein expression, and ultimately, restore normal very-long chain fatty acids (VLCFA) metabolic function. Thus, several key considerations should be addressed when designing AAV-based gene therapy for X-ALD, including the genetic background of the disease and requisite transgene expression levels, the biochemical function of the adrenoleukodystrophy protein (ALDP), the identification of target cells and their role in pathogenesis, the regulation of expression within the genetic construct, the route of administration, the selection of an AAV serotype with high tropism for the central and peripheral nervous systems, and the development of robust in vitro and in vivo models. Full article

The goal of newborn screening (NBS) has remained the same despite its significant expansion from its inception as a public health initiative. This goal is to identify infants that are at risk for a set list of conditions and to implement a care plan to prevent, delay, or mitigate adverse health outcomes for those affected. The role of genetic counselors (GCs) in the NBS space is currently evolving, and there is limited research on parental experiences with genetic counseling for more recently added conditions on a list approved by the U.S. Secretary of Health and Human Services called the Recommended Uniform Screening Panel (RUSP). This qualitative study interviewed parents who have spoken to a genetic counselor after their child was diagnosed with one of three following conditions in the past five years: Pompe disease, X-linked Adrenoleukodystrophy, and Spinal Muscular Atrophy. A total of 13 interviews were conducted and results were organized into five thematic areas: (1) NBS/Results Disclosure, (2) Diagnostic Process after NBS, (3) Treatment/Follow-Up, (4) Communication, and (5) Holistic Support. The findings of this study highlighted parental preferences for early involvement of genetic counselors, provider, and parent education on NBS, and the provision of family support beyond genetic resources. Full article

Background: Adrenoleukodystrophy is a rare, inherited X-linked disease related to mutations in the ABCD1 gene. Peroxisomal β-oxidation is impaired, underpinning the tissue accumulation of very long-chain fatty acids (VLCFAs), especially in the central nervous system (i.e., the white matter and axons), adrenal glands, and testes. VLCFA accumulation contributes to oxidative stress, neuroinflammation, and progressive demyelination, leading to severe neurological sequelae. Though gene therapies and drug development are advancing, dietary management may still play a crucial role in modulating lipid metabolism and mitigating disease progression. Methods: A narrative review of studies published up to May 2025 in major scientific databases was conducted, focusing on biochemical and clinical outcomes, including VLCFA plasma modulation and nutritional status. Results: VLCFA restriction alone has shown limited efficacy due to the counteractive effect of endogenous synthesis. “Lorenzo’s Oil” inhibits VLCFA elongation, yet with inconsistent clinical benefits. Novel dietary strategies, such as the “Bambino Diet” and innovative dietary supplements similar to Lorenzo’s Oil, composed of glyceryl trioleate, glyceryl trierucate, and antioxidants, provide promising biochemical effects, such as reducing VLCFA plasma levels and improving lipid profiles. Malnutrition risk is also increased in X-ALD patients, underscoring the need for personalized nutritional interventions. Conclusions: Dietary strategies are one of the pillars of X-ALD management, to be further combined with pharmacological, gene therapies, and hematopoietic stem cell transplantation. Future research should refine emerging therapies, assess long-term effects, and develop personalized nutritional strategies. Full article

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder, caused by mutations in the ABCD1 gene. Early diagnosis is critical to manage adrenal insufficiency and cerebral forms of the disease. Since 2021, a pilot newborn screening (NBS) program for X-ALD has been launched in Lombardy, Italy. From September 2021 to June 2025, 138,116 newborns (≥37 weeks’ gestational age) were screened for elevated C26:0-lysophosphatidylcholine (C26:0-LPC) levels using a two-tier algorithm. Genetic testing was performed in non-negative cases. Males found to be ABCD1 variant carriers were enrolled in multidisciplinary follow-up, including neurological, endocrinological, and nutritional assessments. Eleven individuals (six males, five females) carried pathogenic or likely pathogenic ABCD1 variants. Three males were diagnosed with adrenal insufficiency and started hydrocortisone therapy between 1 and 2 years of age. Growth parameters were within normal range overall, but two children showed signs of stunting associated with poor dietary compliance. Additionally, three patients were diagnosed with Zellweger spectrum disorders (ZSDs). No patients affected with Aicardi-Goutières Syndrome were identified. Newborn screening for X-ALD in Italy is feasible and enables early detection and intervention. Biochemical markers and genetic analysis are reliable tools for identifying affected males and female carriers. Multidisciplinary management is essential to address medical and psychosocial challenges during follow-up. Full article

The aim of this study was to improve screening efficiency by establishing reasonable interpretation criteria for the use of flow injection analysis tandem mass spectrometry (FIA-MS/MS) in newborn screening (NBS) for X-linked adrenoleukodystrophy (X-ALD). FIA-MS/MS was employed to analyze very-long-chain acylcarnitines (ACs) and lysophosphatidylcholines (LPCs) and their ratios in dried blood spot (DBS) obtained from five X-ALD patients in the neonatal period (0–7 days old) and 7123 healthy neonate controls. By comparing these results and analyzing receiver operating characteristic (ROC) curves, we identified sensitive indicators for X-ALD screening in newborns. To evaluate the performance of different FIA-MS/MS screening indicators, we simultaneously analyzed 7712 neonatal DBS samples obtained for X-ALD screening using FIA-MS/MS and the established liquid chromatography tandem mass spectrometry (LC-MS/MS) method for quantitative detection of C26:0-lysophosphatidylcholine (C26:0-LPC). Furthermore, 84,268 newborn X-ALD screening results were retrospectively analyzed to further evaluate the screening performance of FIA-MS/MS. After the three-step optimization evaluation, the optimized first-tier sensitive screening indicators of FIA-MS/MS were C24:0-AC, C26:0LPC, and C24:0/C22:0-AC. Among the 7712 newborns screened, one case was confirmed to be double-positive. Within separate statistical analyses, based on LC-MS/MS screening alone (positive cutoff > 0.17 µmol/L), only seven cases (0.09%) were initially positive, with a positive predictive value (PPV) of 42.8%, and two additional ABCD1 VUS hemizygous males were detected. Through the retrospective analysis of 84,268 newborns, eight ABCD1 variants (six hemizygous males and two heterozygous females) were ultimately identified. Our study showed that the optimization of first-tier screening performance is particularly important if second-tier screening is not performed. Using LC-MS/MS for second-tier screening for X-ALD can significantly reduce the number of false positives, but the method still misses some false negatives. If it is used as a first-tier assessment, more VUS variant neonates can be detected. Full article

X-linked adrenoleukodystrophy (ALD) is an inherited metabolic disorder that can cause adrenal insufficiency and cerebral ALD (cALD) in childhood. Early detection prevents adverse health outcomes and can be achieved by newborn screening (NBS) followed by monitoring disease progression. However, monitoring is associated with high costs. This study evaluates the cost–effectiveness of NBS for ALD in The Netherlands compared to no screening using a health economic model. A decision tree combined with a Markov model was developed to estimate societal costs, including screening costs, healthcare costs, and productivity losses of parents, and health outcomes over an 18-year time horizon. Model parameters were derived from the literature and expert opinion. A probabilistic sensitivity analysis (PSA) was performed to assess uncertainty. The screening costs of detecting one ALD case by NBS was EUR 40,630. Until the age of 18 years, the total societal cost per ALD case was EUR 120,779 for screening and EUR 62,914 for no screening. Screening gained an average of 1.7 QALYs compared with no screening. This resulted in an incremental cost–effectiveness ratio (ICER) of EUR 34,084 per QALY gained for screening compared to no screening. Although the results are sensitive to uncertainty surrounding costs and effectiveness due to limited data, NBS for ALD is likely to be cost–effective using a willingness-to-pay (WTP) threshold of EUR 50,000– EUR 80,000 per QALY gained. Full article

Background: X-ALD is a white matter (WM) disease caused by mutations in the ABCD1 gene encoding the transporter of very-long-chain fatty acids (VLCFAs) into peroxisomes. Strikingly, the same ABCD1 mutation causes either devastating brain inflammatory demyelination during childhood or, more often, progressive spinal cord axonopathy starting in middle-aged adults. The accumulation of undegraded VLCFA in glial cell membranes and myelin has long been thought to be the central mechanism of X-ALD. Methods: This review discusses studies in mouse and drosophila models that have modified our views of X-ALD pathogenesis. Results: In the Abcd1 knockout (KO) mouse that mimics the spinal cord disease, the late manifestations of axonopathy are rapidly reversed by ABCD1 gene transfer into spinal cord oligodendrocytes (OLs). In a peroxin-5 KO mouse model, the selective impairment of peroxisomal biogenesis in OLs achieves an almost perfect phenocopy of cerebral ALD. A drosophila knockout model revealed that VLCFA accumulation in glial myelinating cells causes the production of a toxic lipid able to poison axons and activate inflammatory cells. Other mouse models showed the critical role of OLs in providing energy substrates to axons. In addition, studies on microglial changing substates have improved our understanding of neuroinflammation. Conclusions: Animal models supporting a primary role of OLs and axonal pathology and a secondary role of microglia allow us to revisit of X-ALD mechanisms. Beyond ABCD1 mutations, pathogenesis depends on unidentified contributors, such as genetic background, cell-specific epigenomics, potential environmental triggers, and stochasticity of crosstalk between multiple cell types among billions of glial cells and neurons. Full article

X-adrenoleukodystrophy (X-ALD) is a peroxisomal metabolic disorder caused by mutations in the ABCD1 gene encoding the peroxisomal ABC transporter adrenoleukodystrophy protein (ALDP). Similar mutations in ABCD1 may result in a spectrum of phenotypes in males with slow progressing adrenomyeloneuropathy (AMN) and fatal cerebral adrenoleukodystrophy (cALD) dominating most cases. Mouse models of X-ALD do not capture the phenotype differences and an appropriate model to investigate the mechanism of disease onset and progress remains a critical need. Here, we generated induced pluripotent stem cell (iPSC) lines from skin fibroblasts of two each of apparently healthy control, AMN, and cALD patients with non-integrating mRNA-based reprogramming. iPSC lines expanded normally and expressed pluripotency markers Oct4, SOX2, NANOG, SSEA, and TRA-1–60. Expression of markers SOX17, Brachyury, Desmin, OXT2, and beta tubulin III demonstrated the ability of the iPSCs to differentiate into all three germ layers. iPSC-derived lines from CTL, AMN, and cALD male patients were differentiated into astrocytes. Differentiated AMN and cALD astrocytes lacked ABCD1 expression and accumulated saturated very long chain fatty acids (VLCFAs), a hallmark of X-ALD, and demonstrated differential mitochondrial bioenergetics, cytokine gene expression, and differences in STAT3 and AMPK signaling between AMN and cALD astrocytes. These patient astrocytes provide disease-relevant tools to investigate the mechanism of differential neuroinflammatory response in X-ALD and will be valuable cell models for testing new therapeutics. Full article

Peroxisomes are ubiquitous, dynamic, oxidative organelles with key functions in cellular lipid metabolism and redox homeostasis. They have been linked to healthy ageing, neurodegeneration, cancer, the combat of pathogens and viruses, and infection and immune responses. Their biogenesis relies on several peroxins (encoded by PEX genes), which mediate matrix protein import, membrane assembly, and peroxisome multiplication. Defects in peroxins or peroxisomal enzymes can result in severe disorders, including developmental and neurological abnormalities. The drive to understand the role of peroxisomes in human health and disease, as well as their functions in tissues and organs or during development, has led to the establishment of vertebrate models. The zebrafish (Danio rerio) has become an attractive vertebrate model organism to investigate peroxisomal functions. Here, we provide an overview of the visualisation of peroxisomes in zebrafish, as well as the peroxisomal metabolic functions and peroxisomal protein inventory in comparison to human peroxisomes. We then present zebrafish models which have been established to investigate peroxisomal disorders. These include model zebrafish for peroxisome biogenesis disorders/Zellweger Spectrum disorders, and single enzyme deficiencies, particularly adrenoleukodystrophy and fatty acid beta-oxidation abnormalities. Finally, we highlight zebrafish models for deficiencies of dually targeted peroxisomal/mitochondrial proteins. Advantages for the investigation of peroxisomes during development and approaches to the application of zebrafish models for drug screening are discussed. Full article

Leukodystrophies represent a heterogeneous group of disorders characterized by specific genetic mutations, metabolic abnormalities, and degeneration of white matter in the central nervous system. These disorders are classified into several categories, with X-linked adrenoleukodystrophy (X-ALD), metachromatic leukodystrophy (MLD), and globoid cell leukodystrophy (GLD) being the most prevalent demyelinating leukodystrophies in pediatric populations. Maintaining proteostasis, which is critical for normal cellular function, relies fundamentally on the ubiquitin–proteasome system (UPS) and autophagy for the degradation of misfolded and damaged proteins. Compelling evidence has highlighted the critical roles of UPS and autophagy dysfunction in the pathogenesis of neurodegenerative diseases. Given the complex and poorly understood pathomechanisms underlying demyelinating leukodystrophies, coupled with the pressing need for effective therapeutic strategies, this review aims to systemically analyze the molecular and pathological evidence linking UPS and autophagy dysfunction to demyelinating leukodystrophies, specifically X-ALD and GLD. Furthermore, we will assess the therapeutic potential of autophagy modulators in the management of X-ALD and GLD, with the objective to inspire further research into therapeutic approaches that target autophagy and UPS pathways. Novel therapies that enhance autophagy and UPS function hold promise as complementary regimens in combination therapies aimed at achieving comprehensive correction of the pathogenic mechanisms in demyelinating leukodystrophies. Full article

X-linked adrenoleukodystrophy (ALD) is a rare metabolic disorder. Symptoms range from cerebral demyelination (cALD) to adrenal insufficiency and slowly progressive myeloneuropathy. cALD is fatal if not treated with hematopoietic cell transplantation in the early stages of the disease course. This can be achieved through cascade testing or newborn screening (NBS). Due to the lack of predictive measures of disease trajectory, patients are monitored with frequent MRI scans and hormone testing to ensure timely intervention. With this study, we wanted to explore how the diagnosis of ALD, before the development of cALD, and the follow-up program affected patients and their parents. Using semi-structured interviews, we interviewed seven parents of children with ALD aged 3–11 and four patients with ALD aged 18–25. Because NBS for ALD has not been implemented in Denmark, the patients were identified through either cascade testing or after having presented with adrenal insufficiency. We generated five themes: (I) ALD patients maintained mental resilience despite diagnosis and surveillance; (II) patients’ concerns matured with age and centered around situations that confronted them with their patient status; (III) parents of children with ALD had both short-term and long-term worries for their children’s health; (IV) parents took on a huge psychological burden; and (V) due to its rarity, the diagnosis of ALD evoked a sense of isolation and disease-related loneliness. Overall, we found a large discrepancy in the experiences reported by parents and patients. Despite the small sample size, we identified patterns that suggest that while the early diagnosis took a significant psychological toll on the parents, patients lived relatively carefree lives despite their ALD diagnosis. Full article

“Bubblegum” acyl-CoA synthetase (ACSBG1) is a pivotal player in lipid metabolism during mouse brain development, facilitating the activation of long-chain fatty acids (LCFA) and their incorporation into lipid species that are crucial for brain function. ACSBG1 converts LCFA into acyl-CoA derivatives, supporting vital metabolic processes. Fruit fly mutants lacking ACSBG1 exhibited neurodegeneration and had elevated levels of very long-chain fatty acids (VLCFA), characteristics of human X-linked adrenoleukodystrophy (XALD). To explore ACSBG1’s function and potential as a therapeutic target in XALD, we created an ACSBG1 knockout (Acsbg1^−/−) mouse and examined the effects on brain FA metabolism during development. Phenotypically, Acsbg1^−/− mice resembled wild type (w.t.) mice. ACSBG1 expression was found mainly in tissue affected pathologically in XALD, namely the brain, adrenal gland and testis. ACSBG1 depletion did not significantly reduce the total ACS enzyme activity in these tissue types. In adult mouse brain, ACSBG1 expression was highest in the cerebellum; the low levels detected during the first week of life dramatically increased thereafter. Unexpectedly, lower, rather than higher, saturated VLCFA levels were found in cerebella from Acsbg1^−/− vs. w.t. mice, especially after one week of age. Developmental changes in monounsaturated ω9 FA and polyunsaturated ω3 FA levels also differed between w.t. and Acsbg1^−/− mice. ACSBG1 deficiency impacted the developmental expression of several cerebellar FA metabolism enzymes, including those required for the synthesis of ω3 polyunsaturated FA, precursors of bioactive signaling molecules like eicosanoids and docosanoids. These changes in membrane lipid FA composition likely affect membrane fluidity and may thus influence the body’s response to inflammation. We conclude that, despite compelling circumstantial evidence, it is unlikely that ACSBG1 directly contributes to the pathology of XALD, decreasing its potential as a therapeutic target. Instead, the effects of ACSBG1 knockout on processes regulated by eicosanoids and/or docosanoids should be further investigated. Full article

Background/Objectives: Adrenoleukodystrophy (X-ALD) is a metabolic disorder caused by dysfunctional peroxisomal beta-oxidation of very-long-chain fatty acids (VLCFAs). A VLCFA-restricted Mediterranean diet has been proposed for patients and carriers to reduce daily VLCFA intake. Methods: We retrospectively evaluated plasma VLCFAs in a cohort of 36 patients and 20 carriers at baseline and after 1 year of restricted diet. Results: At T1, compliant adult patients had significantly lower C26:0 levels [1.7 (1.2) vs. 2.5 µmol/L (1.7), p < 0.05], C26:0/C22:0 ratio [0.04 (0.02) vs. 0.06 (0.03), p < 0.05], and triglycerides [93 (56.5) vs. 128 mg/dL (109.5), p < 0.05] than non-compliant ones. C26:0 [2.4 (1.7) vs. 1.7 (1.2) µmol/L, p < 0.05], the C26:0/C22:0 ratio [0.06 (0.04) vs. 0.04 (0.02), p < 0.05], and cholesterol [173.5 (68.3) mg/dL vs. 157 (54) mg/dL, p < 0.05] were significantly reduced in compliant adult patients at T1 vs. baseline. As for carriers, the C26:0/C22:0 ratio was lower [0.02 (0.01) vs. 0.04 (0.009), p < 0.05] at T1 in compliant carriers, as compared to non-compliant ones. The C26:0/C22:0 [0.03 (0.02) vs. 0.02 (0.01) p < 0.05] and C24:0/C22:0 [1.0 (0.2) vs. 0.9 (0.3), p < 0.05] ratios were significantly decreased at T1 vs. T0. Conclusions: A VLCFA-restricted diet is effective in reducing plasma VLCFA levels and their ratios and must be strongly encouraged as support to therapy. Full article

The state of California (CA) added X-linked adrenoleukodystrophy (X-ALD) to newborn screening (NBS) in 2016 via the measurement of C26:0-lysophosphatidylcholine (C26:0-LPC) in a two-tier fashion, followed by sequencing of the ABCD1 gene. This has resulted in the identification of individuals with genetic conditions beyond X-ALD that can also result in elevated C26:0-LPC by NBS. We describe the biochemical, molecular, and clinical characteristics of nine patients from two metabolic centers in California who screened positive by NBS for elevated C26:0-LPC between 2016 and 2022 and were ultimately diagnosed with a genetic condition other than X-ALD. Seven individuals were diagnosed with Zellweger spectrum disorder (ZSD) due to biallelic variants in PEX genes. One male was diagnosed with Klinefelter syndrome and one female was found to have an X chromosome contiguous gene deletion syndrome after the identification of a heterozygous VUS and hemizygous VUS variant in ABCD1, respectively. Patients with ZSD had significantly higher first- and second-tier C26:0-LPC levels compared to the two non-ZSD cases. Identification of children with ZSD and atypical patterns of ABCD1 variants is a secondary benefit of NBS for X-ALD, leading to earlier diagnosis, prompt therapeutic initiation, and more accurate genetic counseling. As screening for X-ALD continues via the measurement of C26:0-LPC, our knowledge of additional genetic conditions associated with elevated C26:0-LPC will continue to advance, allowing for increased recognition of other genetic disorders for which early intervention is warranted. Full article

Since its discovery in 2012, the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) system has supposed a promising panorama for developing novel and highly precise genome editing-based gene therapy (GT) alternatives, leading to overcoming the challenges associated with classical GT. Classical GT aims to deliver transgenes to the cells via their random integration in the genome or episomal persistence into the nucleus through lentivirus (LV) or adeno-associated virus (AAV), respectively. Although high transgene expression efficiency is achieved by using either LV or AAV, their nature can result in severe side effects in humans. For instance, an LV (NCT03852498)- and AAV9 (NCT05514249)-based GT clinical trials for treating X-linked adrenoleukodystrophy and Duchenne Muscular Dystrophy showed the development of myelodysplastic syndrome and patient’s death, respectively. In contrast with classical GT, the CRISPR/Cas9-based genome editing requires the homologous direct repair (HDR) machinery of the cells for inserting the transgene in specific regions of the genome. This sophisticated and well-regulated process is limited in the cell cycle of mammalian cells, and in turn, the nonhomologous end-joining (NHEJ) predominates. Consequently, seeking approaches to increase HDR efficiency over NHEJ is crucial. This manuscript comprehensively reviews the current alternatives for improving the HDR for CRISPR/Cas9-based GTs. Full article