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

Disorders of fatty acid homeostasis

Humans derive fatty acids (FA) from exogenous dietary sources and/or endogenous synthesis from acetyl-CoA, although some FA are solely derived from exogenous sources ("essential FA"). Once inside cells, FA may undergo a wide variety of different modifications, which include their activation to their corresponding CoA ester, the introduction of double bonds, the 2- and ω-hydroxylation and chain elongation, thereby generating a cellular FA pool which can be used for the synthesis of more complex lipids. The biological properties of complex lipids are very much determined by their molecular composition in terms of the FA incorporated into these lipid species. This immediately explains the existence of a range of genetic diseases in man, often with severe clinical consequences caused by variants in one of the many genes coding for enzymes responsible for these FA modifications. It is the purpose of this review to describe the current state of knowledge about FA homeostasis and the genetic diseases involved. This includes the disorders of FA activation, desaturation, 2- and ω-hydroxylation, and chain elongation, but also the disorders of FA breakdown, including disorders of peroxisomal and mitochondrial α- and β-oxidation.

Hematopoietic Stem Cell Transplantation for Storage Disorders: Present Status

Storage disorders are a group of inborn errors of metabolism caused by the defective activity of lysosomal enzymes or transporters. All of these disorders have multisystem involvement with variable degrees of neurological features. Neurological manifestations are one of the most difficult aspects of treatment concerning these diseases. The available treatment modalities for some of these disorders include enzyme replacement therapy, substrate reduction therapy, hematopoietic stem cell transplantation (HSCT) and the upcoming gene therapies. As a one-time intervention, the economic feasibility of HSCT makes it an attractive option for treating these disorders, especially in lower and middle-income countries. Further, improvements in peri-transplantation medical care, better conditioning regimens and better supportive care have improved the outcomes of patients undergoing HSCT. In this review, we discuss the current evidence for HSCT in various storage disorders and its suitability as a mode of therapy for the developing world.

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.

Differential diagnosis between multiple sclerosis and leukodystrophies - A scoping review

Multiple Sclerosis (MS) is an autoimmune demyelinating disease of the central nervous system (CNS) characterized by damage to the myelin sheaths of oligodendrocytes. Currently, there is no specific biomarker to identify the disease; however, a diagnostic criterion has been established based on patient's clinical, laboratory, and imaging characteristics, which assists in identifying this condition. The primary method for diagnosing MS is the McDonald criteria, first described in 2001 and revised in the years 2005, 2012, and 2017. These criteria have been continuously reviewed to enhance specificity and sensitivity in the diagnosis of MS, thereby reducing errors in its differential diagnosis. An important differential diagnosis that shares overlapping features with MS, mainly the progressive forms, are leukodystrophies with demyelination as underlying pathology. Leukodystrophies comprise a rare group of genetically determined disorders that lead to either demyelination or hypomyelination of the central nervous system that can result neuroimaging changes as well as clinical findings similar to those observed in MS. Thus, systematic evaluation encompassing clinical presentation, neuroimaging findings, and laboratory metrics proves indispensable for a differential diagnosis. As such, this study aimed to establish, clearly and objectively, the similarities and differences between MS and the main demyelinating leukodystrophies. The study analyzed the parameters of the McDonald criteria, including clinical, laboratory, and magnetic resonance imaging aspects, as found in patients with leukodystrophies through scoping literature review. The data were compared with the determinations of the revised 2017 McDonald criteria to facilitate the differential diagnosis of these diseases in clinical practice.

What can pediatricians learn from adult inherited metabolic diseases?

The field of inherited metabolic diseases (IMD) has initially emerged and developed over decades in pediatric departments. Still, today, about 50% of patients with IMD are adults, and adult metabolic medicine (AMM) is getting more structured at national and international levels. There are several domains in which pediatricians can learn from AMM. First, long-term evolution of IMD patients, especially those treated since childhood, is critical to determine nutritional and neuropsychiatric outcomes in adults so that these outcomes can be better monitored, and patient care adjusted as much as possible from childhood. Conversely, the observation of attenuated phenotypes in adults of IMD known to present with severe phenotypes in children calls for caution in the development of newborn screening programs and, more largely, in the interpretation of next-generation sequencing data. Third, it is important for pediatricians to be familiar with adult-onset IMD as they expand our understanding of metabolism, including in children, such as oxysterols and glycogen metabolism. Last, the identification of common molecular and cellular mechanisms in neurodevelopment and neurodegeneration opens the way to synergistic therapeutic developments that will benefit both fields of pediatric and adult medicine. Overall, these observations underline the need of strong interdisciplinarity between pediatricians and adult specialists for the diagnosis and the treatment of IMD well beyond the issues of patient transition from pediatric to adult medicine.

Whole exome sequencing in Serbian patients with hereditary spastic paraplegia

Hereditary spastic paraplegia (HSP) is a group of neurodegenerative diseases with a high genetic and clinical heterogeneity. Numerous HSP patients remain genetically undiagnosed despite screening for known genetic causes of HSP. Therefore, identification of novel variants and genes is needed. Our previous study analyzed 74 adult Serbian HSP patients from 65 families using panel of the 13 most common HSP genes in combination with a copy number variation analysis. Conclusive genetic findings were established in 23 patients from 19 families (29%). In the present study, nine patients from nine families previously negative on the HSP gene panel were selected for the whole exome sequencing (WES). Further, 44 newly diagnosed adult HSP patients from 44 families were sent to WES directly, since many studies showed WES may be used as the first step in HSP diagnosis. WES analysis of cohort 1 revealed a likely genetic cause in five (56%) of nine HSP families, including variants in the ETHE1, ZFYVE26, RNF170, CAPN1, and WASHC5 genes. In cohort 2, possible causative variants were found in seven (16%) of 44 patients (later updated to 27% when other diagnosis were excluded), comprising six different genes: SPAST, SPG11, WASCH5, KIF1A, KIF5A, and ABCD1. These results expand the genetic spectrum of HSP patients in Serbia and the region with implications for molecular genetic diagnosis and future causative therapies. Wide HSP panel can be the first step in diagnosis, alongside with the copy number variation (CNV) analysis, while WES should be performed after.

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.

Adaptive behavior assessed by Vineland-3 as comprehensive outcome measure in vanishing white matter

OBJECTIVES

Investigate the results and usability of the Vineland-3 as an outcome measure in vanishing white matter patients.

METHODS

A cross-sectional investigation of the Vineland-3 based on interviews with caregivers, the Health Utilities Index, and the modified Rankin Scale in 64 vanishing white matter patients.

RESULTS

Adaptive behavior measured with the Vineland-3 is impaired in the vast majority of vanishing white matter patients and significantly impacts daily life. Typically, the daily living skills domain is most severely affected and the socialization domain is the least affected. Based on the metric properties and the clinical relevance, the standard scores for the daily living skills domain and Adaptive Behavior Composite have the best properties to be used as an outcome measure.

INTERPRETATION

The Vineland-3 appears to be a useful outcome measure to explore and quantify complex cognitive, behavioral, and psychiatric impairments affecting daily functioning in vanishing white matter. Further research should address the longitudinal evaluation of this tool and its additional value to standard neuropsychological and clinical examination.

Genetic Myelopathies

OBJECTIVE

This article provides an overview of genetic myelopathies, a diverse group of inherited, degenerative conditions that may be broadly categorized as motor neuron disorders, disorders of spinocerebellar degeneration, leukodystrophies, and hereditary spastic paraplegia. Clinical examples from each category are provided to illustrate the spectrum of genetic myelopathies and their distinguishing features that aid in differentiating genetic myelopathies from potentially treatable acquired causes of myelopathy.

LATEST DEVELOPMENTS

Advances in genetic testing have vastly enhanced current knowledge of genetic myelopathies and the ability to diagnose and provide appropriate counseling to patients and their families. However, potential health care disparities in access to genetic testing is a topic that must be further explored. Although treatment for most of these conditions is typically supportive, there have been recent therapeutic breakthroughs in treatments for amyotrophic lateral sclerosis, spinal muscular atrophy, and Friedreich ataxia.

ESSENTIAL POINTS

Genetic myelopathies may present with chronic and progressive symptoms, a family history of similar symptoms, and involvement of other structures outside of the spinal cord. Imaging often shows spinal cord atrophy, but cord signal change is rare. Exclusion of reversible causes of myelopathy is a key step in the diagnosis. There are many different causes of genetic myelopathies, and in some cases, symptoms may overlap, which underscores the utility of genetic testing in confirming the precise underlying neurologic condition.

Newborn screening for adrenoleukodystrophy: International experiences and challenges

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

X-linked adrenoleukodystrophy and primary adrenal insufficiency

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

Abnormal activation of MAPKs pathways and inhibition of autophagy in a group of patients with Zellweger spectrum disorders and X-linked adrenoleukodystrophy

BACKGROUND

Zellweger spectrum disorders (ZSD) and X-linked adrenoleukodystrophy (X-ALD) are inherited metabolic diseases characterized by dysfunction of peroxisomes, that are essential for lipid metabolism and redox balance. Oxidative stress has been reported to have a significant role in the pathogenesis of neurodegenerative diseases such as peroxisomal disorders, but little is known on the intracellular activation of Mitogen-activated protein kinases (MAPKs). Strictly related to oxidative stress, a correct autophagic machinery is essential to eliminated oxidized proteins and damaged organelles. The aims of the current study are to investigate a possible implication of MAPK pathways and autophagy impairment as markers and putative therapeutic targets in X-ALD and ZSDs.

METHODS

Three patients with ZSD (2 M, 1 F; age range 8-17 years) and five patients with X-ALD (5 M; age range 5- 22 years) were enrolled. A control group included 6 healthy volunteers. To evaluate MAPKs pathway, p-p38 and p-JNK were assessed by western blot analysis on peripheral blood mononuclear cells. LC3II/LC3I ratio was evaluated ad marker of autophagy.

RESULTS

X-ALD and ZSD patients showed elevated p-p38 values on average 2- fold (range 1.21- 2.84) and 3.30-fold (range 1.56- 4.26) higher when compared with controls, respectively. p-JNK expression was on average 12-fold (range 2.20-19.92) and 2.90-fold (range 1.43-4.24) higher in ZSD and X-ALD patients than in controls. All patients had altered autophagic flux as concluded from the reduced LC3II/I ratio.

CONCLUSIONS

In our study X-ALD and ZSD patients present an overactivation of MAPK pathways and an inhibition of autophagy. Considering the absence of successful therapies and the growing interest towards new therapies with antioxidants and autophagy inducers, the identification and validation of biomarkers to monitor optimal dosing and biological efficacy of the treatments is of prime interest.

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

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

Biomarker-based risk prediction for the onset of neuroinflammation in X-linked adrenoleukodystrophy

BACKGROUND

X-linked adrenoleukodystrophy (X-ALD) is highly variable, ranging from slowly progressive adrenomyeloneuropathy to severe brain demyelination and inflammation (cerebral ALD, CALD) affecting males with childhood peak onset. Risk models integrating blood-based biomarkers to indicate CALD onset, enabling timely interventions, are lacking. Therefore, we evaluated the prognostic value of blood biomarkers in addition to current neuroimaging predictors for early detection of CALD.

METHODS

We measured blood biomarkers in a retrospective, male CALD risk-assessment cohort consisting of 134 X-ALD patients and 66 controls and in a phenotype-blinded validation set (25 X-ALD boys, 4-13 years) using Simoa®and Luminex® technologies.

FINDINGS

Among 25 biomarkers indicating axonal damage, astrocye/microglia activation, or immune-cell recruitment, neurofilament light chain (NfL) had the highest prognostic value for early indication of childhood/adolescent CALD. A plasma NfL cut-off level of 8.33 pg/mL, determined in the assessment cohort, correctly discriminated CALD with an accuracy of 96% [95% CI: 80-100] in the validation group. Multivariable logistic regression models revealed that combining NfL with GFAP or cytokines/chemokines (IL-15, IL-12p40, CXCL8, CCL11, CCL22, and IL-4) that were significantly elevated in CALD vs healthy controls had no additional benefit for detecting neuroinflammation. Some cytokines/chemokines were elevated only in childhood/adolescent CALD and already upregulated in asymptomatic X-ALD children (IL-15, IL-12p40, and CCL7). In adults, NfL levels distinguished CALD but were lower than in childhood/adolescent CALD patients with similar (MRI) lesion severity. Blood GFAP did not differentiate CALD from non-inflammatory X-ALD.

INTERPRETATION

Biomarker-based risk prediction with a plasma NfL cut-off value of 8.33 pg/mL, determined by ROC analysis, indicates CALD onset with high sensitivity and specificity in childhood X-ALD patients. A specific pro-inflammatory cytokine/chemokine profile in asymptomatic X-ALD boys may indicate a primed, immanent inflammatory state aligning with peak onset of CALD. Age-related differences in biomarker levels in adult vs childhood CALD patients warrants caution in predicting onset and progression of CALD in adults. Further evaluations are needed to assess clinical utility of the NfL cut-off for risk prognosis of CALD onset.

FUNDING

Austrian Science Fund, European Leukodystrophy Association.

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

BACKGROUND

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

RESULTS

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

CONCLUSIONS

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

Addison's Disease: Diagnosis and Management Strategies

We aim to overview Addison's disease (AD) with regard to current diagnosis and management. This is a narrative review of full-length articles published in English between January 2022 and December 2022 (including online ahead of print versions) in PubMed-indexed journals. We included original studies in living humans regardless of the level of statistical significance starting from the key search terms "Addison's disease" or "primary adrenal insufficiency" in title or abstract. We excluded articles with secondary adrenal insufficiency. Briefly, 199 and 355 papers, respectively were identified; we manually checked each of them, excluded the duplicates, and then selected 129 based on their clinical relevance in order to address our 1-year analysis. We organized the data in different subsections covering all published aspects on the subject of AD. To our knowledge, this is the largest AD retrospective from 2022 on published data. A massive role of genetic diagnosis especially in pediatric cases is highlighted; the importance of both pediatric and adult awareness remains since unusual presentations continue to be described. COVID-19 infection is a strong player amid this third year of pandemic although we still not do have large cohorts in this particular matter as seen, for instance, in thyroid anomalies. In our opinion, the most important topic for research is immune checkpoint inhibitors, which cause a large panel of endocrine side effects, AD being one of them.

Newborn screening for X-linked adrenoleukodystrophy in Italy: Diagnostic algorithm and disease monitoring

Introduction

X-linked adrenoleukodystrophy (X-ALD) is the most common inherited peroxisomal disorder caused by variants in the ABCD1 gene. The main phenotypes observed in men with X-ALD are primary adrenal insufficiency, adrenomyeloneuropathy, and cerebral ALD (cALD). Cerebral ALD consists of a demyelinating progressive cerebral white matter (WM) disease associated with rapid clinical decline and is fatal if left untreated. Hematopoietic stem cell transplantation is the standard treatment for cALD as it stabilizes WM degeneration when performed early in the disease. For this reason, early diagnosis is crucial, and several countries have already implemented their newborn screening programs (NBS) with the assessment of C26:0-lysophosphatidylcholine (C26:0-LPC) values as screening for X-ALD.

Methods

In June 2021, an Italian group in Lombardy launched a pilot study for the implementation of X-ALD in the Italian NBS program. A three-tiered approach was adopted, and it involved quantifying the values of C26:0-LPC and other metabolites in dried blood spots with FIA-MS/MS first, followed by the more specific ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) technique and, finally, the genetic confirmation via focused NGS.

Discussion

Genetically confirmed patients are set to undergo a follow-up protocol and are periodically evaluated to promptly start a specific treatment if and when the first signs of brain damage appear, as suggested by international guidelines. A specific disease monitoring protocol has been created based on literature data and personal direct experience.

Conclusion

The primary aim of this study was to develop a model able to improve the early diagnosis and subsequent follow-up and timely treatment of X-ALD.

Ethics

The study was approved by the local ethics committee. The research was conducted in the absence of any commercial or financial relationship that could be construed as a potential conflict of interest.