An Overview of Molecular Mechanisms in Fabry Disease

Sex Differences in Circulating Inflammatory, Immune, and Tissue Growth Markers Associated with Fabry Disease-Related Cardiomyopathy

Fabry disease (FD) is a lysosomal disorder due to alpha-galactosidase-A enzyme deficiency, accumulation of globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) which lead to proinflammatory effects. Males develop progressive hypertrophic cardiomyopathy (HCM) followed by fibrosis; females develop nonconcentric hypertrophy and/or early fibrosis. The inflammatory response to Gb3/lyso-Gb-3 accumulation is one of the suggested pathogenic mechanisms in FD cardiomyopathy when the secretion of inflammatory and transforming growth factors with infiltration of lymphocytes and macrophages into tissue promotes cardiofibrosis. This study aims to evaluate inflammation-driving cytokines and cardio-hypertrophic remodeling biomarkers contributing to sex-specific HCM progression. Biomarkers were studied in 20 healthy subjects and 45 FD patients. IL-2, IL-10, TNF-α, and IFN-γ were elevated in all patients, while IL-1α, MCP-1, and TNFR2 showed sex-specific differences. The increased cytokines were associated with the NF-kB pathway in FD males with HCM, revealing a correlation between MCP-1, IFN-γ, VEGF, GM-CSF, IL-10, and IL-2. In female patients, the impaired TNFα/TNFR2/TGFβ cluster with correlations to MCP-1, VEGF, GM-CSF, and IL-1α was observed. The activation of cytokines and the NF-kB pathway indicates significant inflammation during HCM remodeling in FD males. The TNFα/TNFR2/TGFβ signaling cluster may explain early fibrosis in females with FD cardiomyopathy. Sex-specific inflammatory responses in FD influence the severity and progression of HCM.

Fabry Disease and Inflammation: Potential Role of p65 iso5, an Isoform of the NF-κB Complex

Fabry disease (FD) is an X-linked lysosomal storage disease, caused by mutations in the GLA gene on the X chromosome, resulting in a deficiency of the lysosomal enzyme α-GAL. This leads to the progressive accumulation of Gb3 in cells, causing multi-systemic effects. FD has been classified as a subgroup of autoinflammatory diseases. NF-κB is a family of ubiquitous and inducible transcription factors that play critical roles in inflammation, in which the p65/p50 heterodimer is the most abundant. The glucocorticoid receptor (GR) represents the physiological antagonists in the inflammation process. A novel spliced variant of p65, named p65 iso5, which can bind the dexamethasone, enhancing GR activity, has been found. This study investigates the potential role of p65 iso5 in the inflammation of subjects with FD. We evaluated in peripheral blood mononuclear cells (PBMCs), from over 100 FD patients, the p65 iso5 mRNA level, and the protein expression. The results showed significantly lower p65 iso5 mRNA and protein expression levels compared to controls. These findings, along with the ability of p65 iso5 to bind dexamethasone and the regulation of the glucocorticoid response in the opposite way of p65, strongly suggest the involvement of p65 iso5 in the inflammatory response in FD.

In vivo confocal microscopic study of cornea verticillata and limbus deposits in patients with Fabry disease

Purpose

This study was aimed to investigate the microstructure characteristics of cornea verticillata and limbus deposits in patients with Fabry disease (FD) using in vivo confocal microscopy (IVCM).

Methods

A total of 60 eyes from 30 patients diagnosed with FD were examined and compared with 36 eyes from 18 healthy controls in this prospective, cross-sectional, controlled, single-center study. The initial assessment of cornea verticillata (CV) was conducted using slit-lamp microscopy. Subsequently, IVCM was performed to assess deposits in the corneal and limbal epithelium. We compared the differences between the sexes (heterozygous and hemizygous) and phenotypes (classical and non-classical).

Results

The epithelial deposit detection rate with IVCM was statistically higher (52/60, 86.67%) compared to the biomicroscopic evaluation of CV using a silt lamp (46/60, 76.67%) (p = 0.031). A higher prevalence of corneal epithelial deposits was observed in the classical phenotype as compared to the non-classical phenotype (p = 0.023). Surprisingly, cardiac variants previously lacking cornea verticillata show a high prevalence (85.71%) of corneal epithelial deposits under IVCM. The prevalence and severity of deposits, especially in limbal epithelial rete pegs, were higher in FD than in controls (p < 0.001).

Conclusion

Compared with slit-lamp microscopy, IVCM provides a more effective tool for examining the epithelial deposits in patients with FD. Patients with FD demonstrated a profound bilateral increase in corneal epithelial deposits and limbal hyperreflective cells compared to controls, with more prominent pathological changes observed in classical phenotype individuals. The high prevalence of epithelial deposits observed through IVCM in the cardiac variant highlights the essential ability of IVCM as an effective diagnostic tool.

Gut-Heart Axis: Microbiome Involvement in Restrictive Cardiomyopathies

An intriguing aspect of restrictive cardiomyopathies (RCM) is the microbiome role in the natural history of the disease. These cardiomyopathies are often difficult to diagnose and so result in significant morbidity and mortality. The human microbiome, composed of billions of microorganisms, influences various physiological and pathological processes, including cardiovascular health. Studies have shown that gut dysbiosis, an imbalance in the composition of intestinal bacteria, can contribute to systemic inflammation, a key factor in many cardiovascular conditions. An increase in gut permeability, frequently caused by dysbiosis, allows bacterial endotoxins to enter the bloodstream, activating inflammatory pathways that exacerbate cardiac dysfunction. Recent reports highlight the potential role of microbiome in amyloidogenesis, as certain bacteria produce proteins that accelerate the formation of amyloid fibrils. Concurrently, advancements in amyloidosis treatments have sparked renewed hopes, marking a promising era for managing these kinds of diseases. These findings suggest that the gut-heart axis may be a potential factor in the development and progression of cardiovascular disease like RCM, opening new paths for therapeutic intervention. The aim of this review is to provide a detailed overview of the gut-heart axis, focusing on RCM.

The Identification of a Novel Pathogenic Variant of the GLA Gene Associated with a Classic Phenotype of Anderson-Fabry Disease: A Clinical and Molecular Study

Anderson-Fabry (or Fabry) disease is a rare lysosomal storage disorder caused by a functional deficiency of the enzyme alpha-galactosidase A. The partial or total defect of this lysosomal enzyme, which is caused by variants in the GLA gene, leads to the accumulation of glycosphingolipids, mainly globotriaosylceramide in the lysosomes of different cell types. The clinical presentation of Fabry disease is multisystemic and can vary depending on the specific genetic variants associated with the disease. To date, more than 1000 different variants have been identified in the human GLA gene, including missense and nonsense variants, as well as small and large insertions or deletions. The identification of novel variants in individuals exhibiting symptoms indicative of Fabry disease, expands the molecular comprehension of the GLA gene, providing invaluable insights to physicians in the diagnosis of the disease. In this article, we present the case of two members of the same family, mother and son, in whom a new pathogenic variant was identified. This variant has not been previously described in the literature and is not present in databases. The two family members presented with a number of typical clinical manifestations of the disease, including cornea verticillata, neuropathic pain, left ventricular hypertrophy, angiokeratomas and abdominal pain. The son, but not his mother, showed reduced alpha-galactosidase A activity, while high levels of Lyso-Gb3 in the blood, a specific substrate accumulation biomarker, were found in both. Sequencing of the GLA gene revealed the presence of a variant, c.484delT, which is characterised by the deletion of a single nucleotide, a thymine, in exon 3 of the gene. This results in a frameshift variant, which introduces a premature stop codon, thereby generating a truncated and consequently non-functional protein. Therefore, the clinical and laboratory data indicate that the novel p.W162Gfs*3 variant described herein is associated with the classical form of Fabry disease.

Preclinical efficacy and safety of adeno-associated virus 5 alpha-galactosidase: A gene therapy for Fabry disease

We developed a novel adeno-associated virus 5 gene therapy (AAV5-GLA) expressing human alpha-galactosidase A (GLA) under the control of a novel, small and strong, liver-restricted promoter. We assessed the preclinical potential of AAV5-GLA for treating Fabry disease, an X-linked hereditary metabolic disorder resulting from mutations in the gene encoding GLA that lead to accumulation of the substrates globotriaosylceramide and globotriaosylsphingosine, causing heart, kidney, and central nervous system dysfunction. Effects of intravenously administered AAV5-GLA were evaluated in (1) GLA-knockout mice aged 7-8 weeks (early in disease) and 20 weeks (nociception phenotype manifestation) and (2) cynomolgus macaques during an 8-week period. In both species, AAV5-GLA was observed as safe, generated detectable vector DNA and mRNA levels in liver, and produced stable enzyme activity in liver and plasma. In mice, dose-dependent transgene enzyme activity, cross-correction (substrate reduction) in kidney and heart, and improved nociception lasted over 6 months. Moreover, after delayed administration when animals displayed the nociception phenotype, target organ enzyme activity was present, and accumulated substrates were reduced. Given the strong, durable expression of active GLA with this promoter and favorable profile of adeno-associated virus 5-based gene therapy in humans, AAV5-GLA warrants further investigation in clinical trials for Fabry disease.

Overcoming Resistance in Anderson-Fabry Disease: Current Therapeutic Challenges and Future Perspectives

Anderson-Fabry disease (AFD) remains a therapeutic challenge despite advances in early diagnosis and the availability of enzyme replacement therapies (ERTs). While early initiation of therapy can mitigate disease progression, resistance mechanisms-such as the development of anti-drug antibodies-limit the efficacy of current treatments, particularly in patients with severe genetic variants. Chaperone therapy provides a targeted option for a subset of patients, yet significant gaps remain in treating those with complete enzyme deficiency. This perspective article explores the existing therapeutic landscape and reflects on emerging treatments, such as mRNA and gene therapies, which hold promise for overcoming the resistance mechanisms. By addressing the limitations of current pharmacological options and considering future innovations, this article aims to outline the path forward for more effective and personalized treatment strategies in Anderson-Fabry disease.

Screening for Fabry Disease-Related Mutations Among 829 Kidney Transplant Recipients

Background/Objectives: Fabry disease (FD) is a genetic lysosomal storage disease caused by a pathogenic variant in GLA gene coding for a functional alpha-galactosidase A enzyme whose disfunction leads to globotriaosylceramide (Gb3) accumulation in cells, which results in multiple organ disorders. The aim of this study was to identify mutations associated with Fabry disease among 829 kidney transplant recipients and to investigate the correlation between the factors such as age, dialysis vintage, eGFR, proteinuria and corticosteroid dose and the deviations in alpha-galactosidase A and lyso-Gb3 levels. Methods: Dry blood spot samples were collected for genetic analysis. The GLA genetic variants were analysed by an amplicon-based next-generation sequencing approach in all female patients and in male patients with reduced alpha-galactosidase A levels. Alpha-galactosidase A and Lyso-Gb3 were not determined in female patients. Pearson's correlation coefficient was used to assess the relationship between the above-mentioned factors with the activity of alpha-galactosidase A and Lyso-Gb3. Results: Genetic testing was performed in 476 patients, all female patients (334), 69 male patients with decreased level of alpha-galactosidase A activity, one male patient with alpha-galactosidase A levels above the quantification limit and 72 male patients with no interpretable results of alpha-galactosidase A activity due to preanalytical error. In 3 (0.4%) male patients, hemizygous mutations associated with Fabry disease were found, and those were c.427G>A p.(Ala143Thr), c.1181T>C p.(Leu394Pro), and c.352C>T p.(Arg118Cys). The dose of corticosteroid therapy seemed to be positively correlated to alpha-galactosidase A activity and negatively to Lyso-Gb3 levels in blood. Conclusions: Genetic testing of individuals with chronic kidney disease and reporting of genetic variants associated with the Fabry phenotype are important to improve the overall knowledge of the disease. Further research is needed to define factors influencing levels of alpha-galactosidase A and Lyso-Gb3.

Ventricular arrhythmias and primary prevention of sudden cardiac death in Anderson-Fabry disease

The Anderson-Fabry disease (AFD) is a X-linked lysosomal storage disorder due to the deficiency in the α-galactosidase A enzyme. Cardiovascular mortality is a major cause of death in patients with AFD and sudden cardiac death (SCD) is one of the main causes of death. The storage of glycosphingolipid along with ionic channel impairment, inflammation and fibrosis are involved in the arrhythmogenesis. Some risk factors have been associated with ventricular tachycardia (VT)/ventricular fibrillation (VF) and SCD. Left ventricular hypertrophy (LVH), cardiac fibrosis, non-sustained VTs seem to be the most important. Older age and male gender might be associated with higher risk of ventricular arrhythmias and SCD. Currently, the implantable cardioverter-defibrillator (ICD) is recommended in patients with AFD who have survived a cardiac arrest secondary to VT/VF or who experienced sustained VT causing syncope or hemodynamic compromise, and have a life expectancy >1 year. ICD implantation is also recommended in patients considered to be at high risk (e.g., patients with severe LVH or fibrosis). The present review sought to summarize the risk of ventricular arrythmias in AFD, the indications for ICD, focusing on pathophysiology and analyzing the role of possible predictors of arrhythmias in preventing SCD, especially as primary prevention.

The Italian Fabry Disease Cardiovascular Registry (IFDCR)

AIMS

The Italian Fabry Disease Cardiovascular Registry (IFDCR) comprises 50 Italian centres with specific expertise in managing cardiovascular manifestations and complications of patients with Fabry disease (FD). The primary aim of the IFDCR is to examine and improve the clinical care and outcomes of patients with FD by addressing several knowledge gaps in the epidemiology, natural history, genotype-phenotype correlations, diagnosis, and management of this condition, with particular focus on cardiovascular manifestations and complications.

METHODS AND RESULTS

The IFDCR is an international, longitudinal, multicentre, non-interventional, observational study. Consecutive patients aged ≥2 years with a diagnosis of FD will be included in the study. The recruitment period consists of two parts: the retrospective enrolment period, from January 1981 to December 2023, and the prospective enrolment period, spanning from January 2024 to December 2031. The registry collects baseline and follow-up data, including the enrolment setting, patient demographics, family history, symptoms, clinical manifestations, electrocardiogram, cardiovascular imaging, laboratory assessment, medical therapy, genetic testing results, and outcomes.

CONCLUSIONS

The IFDCR is a national, multicentre, registry that includes patients with FD. It holds detailed and multiparametric data across the patient pathway and clinical manifestations, acting as a powerful tool for improving the quality of care and conducting high-impact research.

Experts' Opinion in Fabry Disease Management and the Unmet Medical Need: The Saudi Perspective

Fabry disease (FD) is an X-linked lysosomal storage disorder caused by α-galactosidase A gene mutations. Its global incidence ranges from 1:40,000 to 1:170,000. This expert review evaluates the available guidelines, the status of diagnosed but untreated patients with FD, and the challenges in diagnosing and managing FD in the Kingdom of Saudi Arabia (KSA). An advisory board meeting (ABM) was conducted in two phases, with a survey that aimed to receive insights on the current unmet needs in the management of patients with FD in November 2022, and a second, offline meeting in February 2023. The goal of this ABM was to discuss current unmet needs in the management of Fabry patients in the Kingdom of Saudi Arabia. In the first ABM, experts opined on the best practices in the diagnosis, screening, and management of FD for healthcare professionals. These opinions on the management of FD relied on data from research and expert clinical judgments. In the second ABM, the same panel discussed different aspects of FD diagnosis, treatment, and management in the member countries of the Gulf Cooperation Council. The experts discussed the stigma associated with FD, patient awareness and knowledge, genetic screening, biomarkers, and home infusion therapy. They reviewed international guidelines and clinical criteria for enzyme replacement therapy (ERT). Furthermore, they also discussed the diagnosis of FD in men and women, the current guidelines followed for monitoring patients with FD, monitoring untreated patients with FD, Fabry Stabilization IndeX (FASTEX) as an assessment tool for the diagnosis of FD, FD management in KSA, challenges encountered while prescribing ERT in patients with FD, and the clinical criteria for starting ERT. The discussions led to the conclusion that currently, ERT is the only available therapy to manage FD and research should be focused on the early diagnosis and management of FD.

CRISPR/Cas9-based GLA knockout to generate the female Fabry disease human induced pluripotent stem cell line MHHi001-A-15

The X-linked lysosomal storage disorder Fabry disease originates from GLA gene mutations causing α-galactosidase A enzyme deficiency. Here we generated the GLA knockout hiPSC line MHHi001-A-15 (GLA-KOhiPSC) as an in vitro Fabry disease model by targeting exon 2 of the GLA gene by CRISPR/Cas9 in the established control hiPSC line MHHi001-A. GLA-KOhiPSCs retained the expression of pluripotency markers, trilineage differentiation potential, as well as normal karyotype and stem cell morphology but lacked α-galactosidase A enzyme activity. The GLA-KOhiPSCs represent a potent resource to not only study the Fabry disease manifestation but also screen for novel treatment options.

Expanding the Neurological Phenotype of Anderson-Fabry Disease: Proof of Concept for an Extrapyramidal Neurodegenerative Pattern and Comparison with Monogenic Vascular Parkinsonism

Anderson-Fabry disease (AFD) is a genetic sphingolipidosis involving virtually the entire body. Among its manifestation, the involvement of the central and peripheral nervous system is frequent. In recent decades, it has become evident that, besides cerebrovascular damage, a pure neuronal phenotype of AFD exists in the central nervous system, which is supported by clinical, pathological, and neuroimaging data. This neurodegenerative phenotype is often clinically characterized by an extrapyramidal component similar to the one seen in prodromal Parkinson's disease (PD). We analyzed the biological, clinical pathological, and neuroimaging data supporting this phenotype recently proposed in the literature. Moreover, we compared the neurodegenerative PD phenotype of AFD with a classical monogenic vascular disease responsible for vascular parkinsonism and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). A substantial difference in the clinical and neuroimaging features of neurodegenerative and vascular parkinsonism phenotypes emerged, with AFD being potentially responsible for both forms of the extrapyramidal involvement, and CADASIL mainly associated with the vascular subtype. The available studies share some limitations regarding both patients' information and neurological and genetic investigations. Further studies are needed to clarify the potential association between AFD and extrapyramidal manifestations.

Newborn genetic screening for Fabry disease: Insights from a retrospective analysis in Nanjing, China

Fabry disease (FD), an X-linked disorder resulting from dysfunction of α-galactosidase A, can result in significant complications. Early intervention yields better outcomes, but misdiagnosis or delayed diagnosis is common, impacting prognosis. Thus, early detection is crucial in the clinical diagnosis and treatment of FD. While newborn screening for FD has been implemented in certain regions, challenges persist in enzyme activity detection techniques, particularly for female and late-onset patients. Further exploration of improved screening strategies is warranted. This study retrospectively analyzed genetic screening results for pathogenic GLA variants in 17,171 newborns. The results indicated an estimated incidence of FD in the Nanjing region of China of approximately 1 in 1321. The most prevalent pathogenic variant among potential FD patients was c.640-801G > A (46.15 %). Furthermore, the residual enzyme activity of the pathogenic variant c.911G > C was marginally higher than that of other variants, and suggesting that genetic screening may be more effective in identifying potential female and late-onset patients compared to enzyme activity testing. This research offers initial insights into the effectiveness of GLA genetic screening and serves as a reference for early diagnosis, treatment, and genetic counseling in FD.

Prevalence of Fabry disease and GLA variants in young patients with acute stroke: The challenge to widen the screening. The Fabry-Stroke Italian Registry

BACKGROUND

Fabry disease (FD) is a treatable X-linked lysosomal storage disorder caused by GLA gene variants leading to alpha-galactosidase A deficiency. FD is a rare cause of stroke, and it is still controversial whether in stroke patients FD should be searched from the beginning or at the end of the diagnostic workup (in cryptogenic strokes).

METHODS

Fabry-Stroke Italian Registry is a prospective, multicentric screening involving 33 stroke units. FD was sought by measuring α-galactosidase A activity (males) and by genetic tests (males with reduced enzyme activity and females) in patients aged 18-60 years hospitalized for TIA, ischemic stroke, or intracerebral hemorrhage. We diagnosed FD in patients with 1) already known pathogenic GLA variants; 2) novel GLA variants if additional clinical, laboratory, or family-derived criteria were present.

RESULTS

Out of 1906 patients, we found a GLA variant in 15 (0.79%; 95%CI 0.44-1.29) with a certain FD diagnosis in 3 (0.16%; 95%CI 0.03-0.46) patients, none of whom had hemorrhage. We identified 1 novel pathogenic GLA variant. Ischemic stroke etiologies in carriers of GLA variants were: cardioaortic embolism (33%), small artery occlusion (27%), other causes (20%), and undetermined (20%). Mild severity, recurrence, previous TIA, acroparesthesias, hearing loss, and small artery occlusion were predictors of GLA variant.

CONCLUSION

In this large multicenter cohort the frequency of FD and GLA variants was consistent with previous reports. Limiting the screening for GLA variants to patients with cryptogenic stroke may miss up to 80% of diagnoses. Some easily recognizable clinical features could help select patients for FD screening.

Fabry Disease in Women: Genetic Basis, Available Biomarkers, and Clinical Manifestations

Fabry Disease (FD) is a rare lysosomal storage disorder caused by mutations in the GLA gene on the X chromosome, leading to a deficiency in α-galactosidase A (AGAL) enzyme activity. This leads to the accumulation of glycosphingolipids, primarily globotriaosylceramide (Gb3), in vital organs such as the kidneys, heart, and nervous system. While FD was initially considered predominantly affecting males, recent studies have uncovered that heterozygous Fabry women, carrying a single mutated GLA gene, can manifest a wide array of clinical symptoms, challenging the notion of asymptomatic carriers. The mechanisms underlying the diverse clinical manifestations in females remain not fully understood due to X-chromosome inactivation (XCI). XCI also known as "lyonization", involves the random inactivation of one of the two X chromosomes. This process is considered a potential factor influencing phenotypic variation. This review delves into the complex landscape of FD in women, discussing its genetic basis, the available biomarkers, clinical manifestations, and the potential impact of XCI on disease severity. Additionally, it highlights the challenges faced by heterozygous Fabry women, both in terms of their disease burden and interactions with healthcare professionals. Current treatment options, including enzyme replacement therapy, are discussed, along with the need for healthcare providers to be well-informed about FD in women, ultimately contributing to improved patient care and quality of life.

Case report of progressive renal dysfunction as a consequence of amiodarone-induced phospholipidosis

Background

Amiodarone is associated with a range of unwanted effects on pulmonary, thyroid, and liver function. However, the nephrotoxic side effect caused by renal phospholipidosis has hardly received any attention up to now.

Case summary

This is a case of an 86-year-old Caucasian male with an acute on chronic kidney disease 4 months after the initiation of amiodarone. A renal biopsy demonstrated the intracellular accumulation of phospholipids that have previously been demonstrated in association with organ dysfunction because of amiodarone use. Serum creatinine levels subsequently improved from 388 to 314 µmol/L after stopping amiodarone over the course of 2 months.

Discussion

In this case, a diagnosis of partially reversible acute on chronic kidney disease caused by lysosomal phospholipidosis due to amiodarone use was deemed highly likely. Lysosomal dysfunction leads to the accumulation of intra-lysosomal phospholipids (phospholipidosis). This accumulation is accompanied by progressive organ damage and dysfunction, including renal dysfunction, in rare instances. Guidelines advise regular surveillance for liver, lung, and thyroid toxicity during amiodarone treatment but do not mention the potential for renal toxicity. This case suggests that it might be prudent to include screening for renal toxicity in this surveillance.

Cardiovascular Involvement in Fabry's Disease: New Advances in Diagnostic Strategies, Outcome Prediction and Management

Cardiovascular involvement is common in Fabry's disease and is the leading cause of morbidity and mortality. The research is focused on identifying diagnostic clues suggestive of cardiovascular involvement in the preclinical stage of the disease through clinical and imaging markers. Different pathophysiologically driven therapies are currently or will soon be available for the treatment of Fabry's disease, with the most significant benefit observed in the early stages of the disease. Thus, early diagnosis and risk stratification for adverse outcomes are crucial to determine when to start an aetiological treatment. This review describes the cardiovascular involvement in Fabry's disease, focusing on the advances in diagnostic strategies, outcome prediction and disease management.