Urinary globotriaosylceramide excretion correlates with the genotype in children and adults with Fabry disease

Clinical relevance of globotriaosylceramide accumulation in Fabry disease and the effect of agalsidase beta in affected tissues

Fabry disease (FD) is a rare lysosomal storage disorder, characterized by a reduction in α-galactosidase A enzyme activity and the progressive accumulation of globotriaosylceramide (GL3) and its metabolites in the cells of various organs. Agalsidase beta, an enzyme replacement therapy (ERT), is approved for use in patients with FD in Europe, Canada, Australia, South America, and Asia, and is the only ERT approved for use in the United States. In this review, we discuss the clinical relevance of GL3 accumulation, the effect of agalsidase beta on GL3 in target tissues, and the association between treatment-related tissue GL3 clearance and long-term structure, function, or clinical outcomes. Accumulation of GL3 in the kidney, heart, vasculature, neurons, skin, gastrointestinal tract and auditory system correlates to cellular damage and irreversible organ damage, as a result of sclerosis, fibrosis, apoptosis, inflammation, and endothelial dysfunction. Damage leads to renal dysfunction and end-stage renal disease; myocardial hypertrophy with heart failure and arrhythmias; ischemic stroke; neuropathic pain; skin lesions; intestinal ischemia and dysmotility; and hearing loss. Treatment with agalsidase beta is effective in substantially clearing GL3 in a range of cells from the tissues affected by FD. Agalsidase beta has also been shown to slow renal decline and lower the overall risk of clinical progression, demonstrating an indirect link between treatment-related GL3 clearance and stabilization of FD.

Inhibition of epigenetic reader proteins by apabetalone counters inflammation in activated innate immune cells from Fabry disease patients receiving enzyme replacement therapy

Fabry disease (FD) is a rare X‐linked disorder of lipid metabolism, characterized by the accumulation of globotriaosylceramide (Gb3) due to defective the lysosomal enzyme, α‐galactosidase. Gb3 deposits activate immune‐mediated systemic inflammation, ultimately leading to life‐threatening consequences in multiple organs such as the heart and kidneys. Enzyme replacement therapy (ERT), the standard of care, is less effective with advanced tissue injury and inflammation in patients with FD. Here, we showed that MCP‐1 and TNF‐α cytokine levels were almost doubled in plasma from ERT‐treated FD patients. Chemokine receptor CCR2 surface expression was increased by twofold on monocytes from patients with low eGFR. We also observed an increase in IL12B transcripts in unstimulated peripheral blood mononuclear cells (PBMCs) over a 2‐year period of continuous ERT. Apabetalone is a clinical‐stage oral bromodomain and extra terminal protein inhibitor (BETi), which has beneficial effects on cardiovascular and kidney disease related pathways including inflammation. Here, we demonstrate that apabetalone, a BD2‐selective BETi, dose dependently reduced the production of MCP‐1 and IL‐12 in stimulated PBMCs through transcriptional regulation of their encoding genes. Reactive oxygen species production was diminished by up to 80% in stimulated neutrophils following apabetalone treatment, corresponding with inhibition of NOX2 transcription. This study elucidates that inhibition of BET proteins by BD2‐selective apabetalone alleviates inflammatory processes and oxidative stress in innate immune cells in general and in FD. These results suggest potential benefit of BD2‐selective apabetalone in controlling inflammation and oxidative stress in FD, which will be further investigated in clinical trials.

Methylmalonic acid analysis using urine filter paper samples to screen for metabolic vitamin B12 deficiency in older adults

Aim: Methylmalonic acid (MMA) analysis in urine represents a noninvasive approach to screening for vitamin B₁₂ deficiency in older adults. A method allowing the analysis of MMA/creatinine in fasting urine collected on filter paper was developed/validated. Method: Dry urine specimens were eluted using a solution containing internal standards, filtrated and analyzed by ultra-performance LC-MS/MS. Results: The method allowed the chromatographic separation of MMA from succinic acid. Dried urine samples were stable for 86 days at room temperature. The MMA/creatinine ratios measured in urine collected on filter paper were highly correlated with values derived from the corresponding liquid specimens. Conclusion: This robust filter paper method might greatly improve the accessibility and cost-effectiveness of vitamin B₁₂ deficiency screening in older adults.

Clinical Characteristics, Renal Involvement, and Therapeutic Options of Pediatric Patients With Fabry Disease

Inherited renal diseases represent 20% of the causes of end-stage renal diseases. Fabry disease, an X-linked lysosomal storage disorder, results from α-galactosidase A deficient or absent activity followed by globotriaosylceramide (Gb3) accumulation and multiorgan involvement. In Fabry disease, kidney involvement starts early, during intrauterine life by the Gb3 deposition. Even if chronic kidney disease (CKD) is discovered later in adult life in Fabry disease patients, a decline in glomerular filtration rate (GFR) can occur during adolescence. The first clinical sign of kidney involvement is represented by albuminuria. So, early and close monitoring of kidneys function is required: albuminuria and proteinuria, urinary albumin-to-creatinine ratio, serum creatinine, or cystatin C to estimate GFR, while urinary sediment with phase-contrast microscopy under polarized light may be useful in those cases where leucocyte α-Gal A activity and GLA genotyping are not available. Children with Fabry disease and kidney involvement should receive enzyme replacement therapy and nephroprotective drugs (angiotensin-converting enzyme inhibitors or angiotensin receptor blockers) to prevent or slow the progressive loss of kidney functions. Early diagnosis of Fabry disease is important as enzyme replacement therapy reduces symptoms, improves clinical features and biochemical markers, and the quality of life. More importantly, early treatment could slow or stop progressive organ damage in later life.

Biomarkers in Anderson-Fabry Disease

Fabry disease is a rare lysosomal storage disorder caused by a deficiency of α-galactosidase A, resulting in multisystemic involvement. Lyso-Gb3 (globotriaosylsphingosine), the deacylated form of Gb3, is currently measured in plasma as a biomarker of classic Fabry disease. Intensive research of biomarkers has been conducted over the years, in order to detect novel markers that may potentially be used in clinical practice as a screening tool, in the context of the diagnostic process and as an indicator of response to treatment. An interesting field of application of such biomarkers is the management of female heterozygotes who present difficulty in predictable clinical progression. This review aims to summarise the current evidence and knowledge about general and specific markers that are actually measured in subjects with confirmed or suspected Fabry disease; moreover, we report potential novel markers such as microRNAs. Recent proteomic or metabolomic studies are in progress bringing out plasma proteome profiles in Fabry patients: this assessment may be useful to characterize molecular pathology of the disease, to improve diagnostic process, and to monitor response to treatment. The management of Fabry disease may be improved by the identification of biomarkers that reflect clinical course, severity, and the progression of the disease.

Globotriaosylsphingosine (lyso-Gb3) and analogues in plasma and urine of patients with Fabry disease and correlations with long-term treatment and genotypes in a nationwide female Danish cohort

INTRODUCTION

Recent studies showed the usefulness of globotriaosylsphingosine (lyso-Gb₃) and related analogues, deacylated forms of globotriaosylceramide (Gb₃), for high-risk screening, treatment monitoring and follow-up for patients with Fabry disease.

METHODS

We evaluated Gb₃, lyso-Gb₃ and analogues using tandem mass spectrometry in 57 women with Fabry disease followed during a period of 15.4 years. Twenty-one women were never treated and 36 received treatment (agalsidase-beta, n=30; agalsidase-alfa, n=5; or migalastat, n=1). Lyso-Gb₃ and analogues at m/z (-28), (-2), (+16), (+34) and (+50) were analysed in plasma and urine. Total Gb₃ and lyso-Gb₃ analogues at m/z (-12) and (+14) were evaluated in urine while the analogue at m/z (+18) was evaluated in plasma.

RESULTS

A strong correlation between plasma and urine lyso-Gb₃ and analogue levels was revealed. Plasma and urine lyso-Gb₃ and analogue levels were not statistically different between patients carrying missense (n=49), nonsense (n=6) or deletion mutations (n=2). Never treated patients had lower plasma lyso-Gb₃ and analogues at m/z (-28), (-2), (+16), (+34) and the seven urinary lyso-Gb₃ analogues compared with pretreatment levels of the treated patients. A significant reduction of plasma lyso-Gb₃ and five analogues, as well as urine Gb₃ and six lyso-Gb₃ analogues, but not lyso-Gb₃ and lyso-Gb₃ at m/z (+50), was observed post-treatment with agalsidase-beta. The same tendency was observed with agalsidase-alfa.

CONCLUSION

Women with Fabry disease who started treatment based on clinical manifestations had higher lyso-Gb₃ and analogue biomarker levels than never treated women. This indicates that a biomarker cut-off could potentially be a decision tool for treatment initiation in women with Fabry disease.

Diurnal Variation of Urinary Fabry Disease Biomarkers during Enzyme Replacement Therapy Cycles

Fabry disease is an X-linked lysosomal storage disorder caused by mutations in the GLA gene encoding the α-galactosidase A enzyme. This enzyme cleaves the last sugar unit of glycosphingolipids, including globotriaosylceramide (Gb₃), globotriaosylsphingosine (lyso-Gb₃), and galabiosylceramide (Ga₂). Enzyme impairment leads to substrate accumulation in different organs, vascular endothelia, and biological fluids. Enzyme replacement therapy (ERT) is a commonly used treatment. Urinary analysis of Gb₃ isoforms (different fatty acid moieties), as well as lyso-Gb₃ and its analogues, is a reliable way to monitor treatment. These analogues correspond to lyso-Gb₃ with chemical modifications on the sphingosine moiety (−C₂H₄, −C₂H₄+O, −H₂, −H₂+O, +O, +H₂O₂, and +H₂O₃). The effects of sample collection time on urinary biomarker levels between ERT cycles were not previously documented. The main objective of this project was to analyze the aforementioned biomarkers in urine samples from seven Fabry disease patients (three treated males, three treated females, and one ERT-naïve male) collected twice a day (morning and evening) for 42 days (three ERT cycles). Except for one participant, our results show that the biomarker levels were generally more elevated in the evening. However, there was less variability in samples collected in the morning. No cyclic variations in biomarker levels were observed between ERT infusions.

Genetic architecture of common non-Alzheimer's disease dementias

Frontotemporal dementia (FTD), dementia with Lewy bodies (DLB) and vascular dementia (VaD) are the most common forms of dementia after Alzheimer's disease (AD). The heterogeneity of these disorders and/or the clinical overlap with other diseases hinder the study of their genetic components. Even though Mendelian dementias are rare, the study of these forms of disease can have a significant impact in the lives of patients and families and have successfully brought to the fore many of the genes currently known to be involved in FTD and VaD, starting to give us a glimpse of the molecular mechanisms underlying these phenotypes. More recently, genome-wide association studies have also pointed to disease risk-associated loci. This has been particularly important for DLB where familial forms of disease are very rarely described. In this review we systematically describe the Mendelian and risk genes involved in these non-AD dementias in an effort to contribute to a better understanding of their genetic architecture, find differences and commonalities between different dementia phenotypes, and uncover areas that would benefit from more intense research endeavors.

Therapeutic challenges in two adolescent male patients with Fabry disease and high antibody titres

Enzyme replacement therapy (ERT) has been shown to stabilize certain aspects of Fabry disease (FD). However, in some patients on ERT, high antibody titres have been documented, with limited clinical improvement in systemic manifestations and often with significant adverse drug reactions. We present two related adolescent males with a 4.5 kb GLA deletion, not amenable to chaperone therapy, leading to profound reduction in α-galactosidase A (α-gal A) enzyme activity. Over a 3-year period of ERT, increasing IgG antibody titres against α-gal A were noted. After starting ERT serial urine globotriaosylceramide (Gb₃) measurements showed an upward trend from 333 to 2260 μg/mmol creatinine for patient 1 and 1165 to 2260 μg/mmol creatinine for patient 2. Markedly increased levels of urine and plasma globotriaosylsphingosine (Lyso-Gb₃₎ analogues were also found. The patients experienced recurrent infusion-associated reactions necessitating premedication and prolonged infusion times. Over the 3-year period of ERT, the patients experienced continued malaise, gastrointestinal symptoms and neuropathic pain. In addition, they had increasing anxiety related to their disease and apparent lack of response to ERT which led to a decision to ultimately stop ERT. No other approved treatment options are currently available for these patients. It is possible that the rapid development of the high antidrug neutralizing antibody (ADA) titres is related to the large GLA deletion leading to virtually absent enzyme activity. It remains unclear if their symptomatology during the period of receiving ERT is related to lack of its efficacy, the rising ADA titres, or both. These two patients highlight the need for further research into the management of antidrug antibodies and additional therapeutic approaches for FD.

Synopsis

The development of very high antidrug antibody titres in response to ERT in two related adolescent males with FD highlight the need for other therapeutic options for patients in whom ERT or other currently approved therapies does not meet their treatment needs.

Tandem mass spectrometry analysis of urinary podocalyxin and podocin in the investigation of podocyturia in women with preeclampsia and Fabry disease patients

BACKGROUND

Podocytes are highly differentiated visceral cells, and several related specific proteins, such as podocalyxin and podocin are potential tools for the evaluation of podocyturia. However, precise quantitation of podocyturia-related proteins is complex and often unreliable.

METHOD

A reversed-phase ultra-performance liquid chromatography coupled to tandem mass spectrometry method was developed and validated to quantify podocalyxin and podocin levels in urine supernatant by using specific cleavable peptides and standards. Urine samples from women with normotensive or hypertensive pregnancies, gestational diabetes and preeclampsia, as well as treated and untreated Fabry patients, and gender-matched controls were investigated.

RESULTS

The multiplex analysis shows that podocalyxin levels were higher than podocin levels in patients, the former being particularly higher in pregnant women. Women with preeclampsia had abnormal urine levels of both proteins with a higher sensitivity for podocalyxin. Slightly increased levels of podocin were also observed in Fabry males, while both proteins were increased in untreated Fabry females. Correlations were established between podocalyxin and podocin levels and clinical parameters associated with Fabry disease and preeclampsia.

CONCLUSIONS

This methodology makes possible the precise, simultaneous and reliable analysis of podocalyxin and podocin levels, and offers a valuable tool for the evaluation of podocyturia.

Multiple phenotypic domains of Fabry disease and their relevance for establishing genotype- phenotype correlations

Fabry disease (FD) is a rare X-linked glycosphingolipidosis resulting from deficient α-galactosidase A (AGAL) activity, caused by pathogenic mutations in the GLA gene. In males, the multisystemic involvement and the severity of tissue injury are critically dependent on the level of AGAL residual enzyme activity (REA) and on the metabolic load of the disease, but organ susceptibility to damage varies widely, with heart appearing as the most vulnerable to storage pathology, even with relatively high REA. The expression of FD can be conceived as a multidomain phenotype, where each of the component domains is the laboratory or clinical expression of the causative GLA mutation along a complex pathophysiologic cascade pathway. The AGAL enzyme activity is the most clinically useful marker of the protein phenotype. The metabolic phenotype and the pathologic phenotype are diverse expressions of the storage pathology, respectively, assessed by biochemical and histological/ultrastructural methods. The storage phenotypes are the direct consequences of enzyme deficiency and hence, together with the enzymatic phenotype, constitute the more specific diagnostic markers of FD. In the pathophysiology cascade, the clinical phenotypes are most distantly linked to the underlying genetic causation, being critically influenced by the patients’ gender and age, and modulated by the effects of variation in other genetic loci, of polygenic inheritance and of environmental risk factors. A major challenge in the clinical phenotyping of patients with FD is the differential diagnosis between its nonspecific, later-onset complications, particularly the cerebrovascular, cardiac and renal, and similar chronic illnesses that are common in the general population. Comprehensive phenotyping, whenever possible performed in hemizygous males, is therefore crucial for grading the severity of pathogenic GLA variants, to clarify the phenotypic correlations of hypomorphic alleles, to define benign polymorphisms, as well as to establish the pathogenicity of variants of uncertain significance.

UPLC–MS/MS analysis of keratan sulfate from urine samples collected on filter paper for monitoring & follow-up of Morquio A patients

Aim: Since 2014, enzyme replacement therapy (ERT) has been available for treatment of Morquio A syndrome. During clinical trials, urinary keratan sulfate (KS) has been a useful biomarker and showed a marked decrease in patients on ERT, demonstrating therapy efficacy. Unfortunately, quantitative urinary KS testing is not widely available in biochemical genetics laboratories for efficient monitoring and follow-up of treated patients. Materials & methods: A tandem mass spectrometry methodology was devised to analyze KS disaccharides and creatinine in urine specimens collected on filter paper. Results: All Morquio A patients presented abnormal results pretreatment compared with reference values. Conclusion: This collection procedure can be performed by patients at home and filter papers sent by regular mail to a specialized laboratory, facilitating follow-up of patients.

Urine-derived cells: a promising diagnostic tool in Fabry disease patients

Fabry disease is a lysosomal storage disorder resulting from impaired alpha-galactosidase A (α-Gal A) enzyme activity due to mutations in the GLA gene. Currently, powerful diagnostic tools and in vivo research models to study Fabry disease are missing, which is a major obstacle for further improvements in diagnosis and therapy. Here, we explore the utility of urine-derived primary cells of Fabry disease patients. Viable cells were isolated and cultured from fresh urine void. The obtained cell culture, modeling the renal epithelium, is characterized by patient-specific information. We demonstrate that this non-invasive source of patient cells provides an adequate cellular in vivo model as cells exhibit decreased α-Gal A enzyme activity and concomitant globotriaosylceramide accumulation. Subsequent quantitative proteomic analyses revealed dysregulation of endosomal and lysosomal proteins indicating an involvement of the Coordinated Lysosomal Expression and Regulation (CLEAR) network in the disease pathology. This proteomic pattern resembled data from our previously described human podocyte model of Fabry disease. Taken together, the employment of urine-derived primary cells of Fabry disease patients might have diagnostic and prognostic implications in the future. Our findings pave the way towards a more detailed understanding of pathophysiological mechanisms and may allow the development of future tailored therapeutic strategies.

A Liquid Chromatography-Quadrupole-Time-of-Flight Mass Spectrometric Assay for the Quantification of Fabry Disease Biomarker Globotriaosylceramide (GB3) in Fabry Model Mouse

Fabry disease is a rare lysosomal storage disorder resulting from the lack of α-Gal A gene activity. Globotriaosylceramide (GB3, ceramide trihexoside) is a novel endogenous biomarker which predicts the incidence of Fabry disease. At the early stage efficacy/biomarker study, a rapid method to determine this biomarker in plasma and in all relevant tissues related to this disease simultaneously is required. However, the limited sample volume, as well as the various levels of GB3 in different matrices makes the GB3 quantitation very challenging. Hereby we developed a rapid method to identify GB3 in mouse plasma and various tissues. Preliminary stability tests were also performed in three different conditions: short-term, freeze-thaw, long-term. The calibration curve was well fitted over the concentration range of 0.042–10 μg/mL for GB3 in plasma and 0.082–20 μg/g for GB3 in various tissues. This method was successfully applied for the comparison of GB3 levels in Fabry model mice (B6;129-Gla^tm1Kul/J), which has not been performed previously to the best of our knowledge.

Investigation of correlation of urinary globotriaosylceramide (Gb3) levels with markers of renal function in patients with Fabry disease

Fabry disease (FD) is a disorder that results from mutations of hydrolase α-galactosidase A. The enzymatic defect leads to accumulation of globotriaosylceramide (Gb3) in the kidney. Substrate deposition is related to tissue damage in FD, but the relation of urinary Gb3 levels in patients and the renal function markers remain not completely understood. Once nephropathy is one of the main features of FD and is marked by an insidious development, we investigated a possible correlation of Gb3 with biochemical markers of nephropathy including albuminuria, estimated glomerular filtration rate (eGFR), serum creatinine and urea, and proteinuria in male and female patients under or not enzyme replacement therapy (ERT).Gb3, proteinuria and albuminuria were increased in male and female FD patients. We found no correlation between urinary Gb3 levels and all renal function parameters evaluated in Fabry patients (in both sexes and using or not ERT). On the other hand, albuminuria showed negative correlation with eGFR only in male under or not ERT, demonstrating that albuminuria seems to be an early marker of renal function alteration. In conclusion, the results suggest that urinary Gb3 level does not reflect the renal function and that albuminuria is an important biomarker in male FD patients.

Low frequency of Fabry disease in patients with common heart disease

PURPOSE

To test the hypothesis that undiagnosed patients with Fabry disease exist among patients affected by common heart disease.

METHODS

Globotriaosylceramide in random whole urine using tandem mass spectroscopy, α-galactosidase A activity in dried blood spots, and next-generation sequencing of pooled or individual genomic DNA samples supplemented by Sanger sequencing.

RESULTS

We tested 2,256 consecutive patients: 852 women (median age 65 years (19-95)) and 1,404 men (median age 65 years (21-92)). The primary diagnoses were coronary artery disease (n = 994), arrhythmia (n = 607), cardiomyopathy (n = 138), and valvular disease (n = 568). Urinary globotriaosylceramide was elevated in 15% of patients and 15 males had low α-galactosidase A activity. GLA variants found included R118C (n = 2), D83N, and D313Y (n = 7); IVS6-22 C>T, IVS4-16 A>G, IVS2+990C>A, 5'UTR-10 C>T (n = 4), IVS1-581 C>T, IVS1-1238 G>A, 5'UTR-30 G>A, IVS2+590C>T, IVS0-12 G>A, IVS4+68A>G, IVS0-10 C>T, IVS2-81-77delCAGCC, IVS2-77delC. Although the pathogenicity of several of these missense mutations and complex intronic haplotypes has been controversial, none of the patients screened in this study were diagnosed definitively with Fabry disease.

CONCLUSION

This population of patients with common heart disease did not contain a substantial number of patients with undiagnosed Fabry disease. GLA gene sequencing is superior to urinary globotriaosylceramide or α-galactosidase A activity in the screening for Fabry disease.

High-Risk Screening for Fabry Disease: Analysis by Tandem Mass Spectrometry of Globotriaosylceramide (Gb3 ) in Urine Collected on Filter Paper

Fabry disease is a complex, panethnic lysosomal storage disorder. It is characterized by the accumulation of glycosphingolipids in tissues, organs, the vascular endothelium, and biological fluids. The reported incidence in different populations is quite variable, ranging from 1:1400 to 1:117,000. Its complexity lies in the marked genotypic and phenotypic heterogeneity. Despite the fact that it is an X-linked disease, more than 600 mutations affect both males and females. In fact, some females may be affected as severely as males. The purpose of this protocol is to focus on the high-risk screening of patients who might have Fabry disease using a simple, rapid, non-invasive high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for urinary globotriaosylceramide (Gb₃ ) analysis. Urine filter paper samples are easily collected at home by patients and sent by regular mail. This method has been successfully used for high-risk screening of patients with ophthalmologic manifestations and in an on-going study for high-risk screening of Fabry disease in patients with chronic kidney diseases. © 2017 by John Wiley & Sons, Inc.

Biomarkers associated with clinical manifestations in Fabry disease patients with a late-onset cardiac variant mutation

BACKGROUND

Fabry disease is a lysosomal storage disorder with an incidence of 1:1600 for the late-onset IVS4+919G>A cardiac variant mutation in Taiwan. Signs and symptoms of this cardiac variant include left ventricular hypertrophy, mitral insufficiency and/or arrhythmias. The search for biomarkers that might predict the clinical outcomes and guide treatment options is important. We thus investigated relationships between Fabry disease biomarkers (such as globotriaosylceramide (Gb₃), globotriaosylsphingosine (lyso-Gb₃)/related analogues) and age, gender, enzyme activity, clinical manifestations and severity of the disease in these patients.

METHOD

Urine and plasma biomarkers were analyzed using tandem mass spectrometry. A large cohort of 191 adult and pediatric Fabry patients carrying the IVS4+919G>A mutation was studied. Some patients were members of the same family.

RESULTS

Our results show that the plasma lyso-Gb₃ level, and urinary analogue levels of lyso-Gb₃ at m/z (+16), (+34), and (+50) adjusted for gender and age had a positive association with the left ventricular mass index, and/or the Mainz Severity Score Index.

CONCLUSIONS

It might thus be of particular interest to monitor children with high levels of these biomarkers, as part of a longitudinal study in order to determine if the excretion profile at a young age is predictive of the outcomes of disease severity in adulthood.

The Large Phenotypic Spectrum of Fabry Disease Requires Graduated Diagnosis and Personalized Therapy: A Meta-Analysis Can Help to Differentiate Missense Mutations

Fabry disease is caused by mutations in the GLA gene and is characterized by a large genotypic and phenotypic spectrum. Missense mutations pose a special problem for graduating diagnosis and choosing a cost-effective therapy. Some mutants retain enzymatic activity, but are less stable than the wild type protein. These mutants can be stabilized by small molecules which are defined as pharmacological chaperones. The first chaperone to reach clinical trial is 1-deoxygalactonojirimycin, but others have been tested in vitro. Residual activity of GLA mutants has been measured in the presence or absence of pharmacological chaperones by several authors. Data obtained from transfected cells correlate with those obtained in cells derived from patients, regardless of whether 1-deoxygalactonojirimycin was present or not. The extent to which missense mutations respond to 1-deoxygalactonojirimycin is variable and a reference table of the results obtained by independent groups that is provided with this paper can facilitate the choice of eligible patients. A review of other pharmacological chaperones is provided as well. Frequent mutations can have residual activity as low as one-fourth of normal enzyme in vitro. The reference table with residual activity of the mutants facilitates the identification of non-pathological variants.

Fabry Disease: A Disorder of Childhood Onset

BACKGROUND

Fabry disease, an X-linked disorder of glycosphingolipids, markedly increases the risk of systemic vasculopathy, ischemic stroke, small-fiber peripheral neuropathy, cardiac dysfunction, and chronic kidney disease.

METHODS

We performed an extensive PubMed search on the topic of Fabry disease and drew from our cumulative 43 years of experience.

RESULTS

Most of these complications are nonspecific in nature and clinically indistinguishable from similar abnormalities that occur in the context of more common disorders in the general population. This disease is caused by variants of the GLA gene, and its incidence may have been underestimated. However, one must also guard against overdiagnosis of Fabry disease and unjustified enzyme replacement therapy, because some of the gene variants are benign. Specific therapy for Fabry disease has been developed in the last few years, but its clinical effect has been modest. Novel therapeutic agents are being developed. Standard "nonspecific" medical and surgical therapy is necessary and effective in slowing deterioration or compensating for organ failure in patients with Fabry disease.

CONCLUSIONS

Fabry disease is a treatable and modifiable genetic risk factor for a myriad of clinical organ complications. Fabry disease may be frequently overlooked but on occasion overdiagnosed.

Tandem Mass Spectrometry of Sphingolipids: Applications for Diagnosis of Sphingolipidoses

In recent years, mass spectrometry (MS) has become the dominant technology in lipidomic analysis. It is widely used in diagnosis and research of lipid metabolism disorders including those characterized by impairment of lysosomal functions and storage of nondegraded-degraded substrates. These rare diseases, which include sphingolipidoses, have severe and often fatal clinical consequences. Modern MS methods have contributed significantly to achieve a definitive diagnosis, which is essential in clinical practice to begin properly targeted patient care. Here we summarize MS and tandem MS methods used for qualitative and quantitative analysis of sphingolipids (SL) relative to the diagnostic process for sphingolipidoses and studies focusing on alterations in cell functions due to these disorders. This review covers the following topics: Tandem MS is sensitive and robust in determining the composition of sphingolipid classes in various biological materials. Its ability to establish SL metabolomic profiles using MS bench-top analyzers, significantly benefits the first stages of a diagnosis as well as metabolic studies of these disorders. It can thus contribute to a better understanding of the biological significance of SL.

Relative distribution of Gb3 isoforms/analogs in NOD/SCID/Fabry mice tissues determined by tandem mass spectrometry

AIM

Fabry disease is a lysosomal storage disorder leading to glycosphingolipid accumulation in different organs, tissues and biological fluids. The development of a Fabry disease gene therapy trial is underway in Canada. A tool to determine the distribution of Gb3 biomarkers in tissues of Fabry mice might be applicable to monitor the effect of gene therapy. Results & methodology: An ultra-performance LC-MS/MS (UPLC-MS/MS) method for the analysis of 22 Gb3 isoform/analogs in various Fabry mice tissues was developed and validated. Marked variation in biomarker organ distribution was found with higher levels in the spleen, followed by the small intestine, kidneys, lungs, heart, liver and brain.

CONCLUSION

The devised method is sensitive and useful for the evaluation of biomarker profiles in Fabry mice.

Enhancement of human plasma glucosylceramide assay sensitivity using delipidized plasma

Glucosylceramide (GL-1) level in human has been considered as a surrogate biomarker for enzyme replacement and substrate reduction therapies (ERT and SRT) for Gaucher and Fabry patients. Due to the high endogenous level of GL-1 in human plasma, it is difficult to achieve the analytical sensitivity of plasma GL-1 below the normal endogenous level (1.7 μg/mL to 6.6 μg/mL) when using the standard addition method and regular plasma matrix for standard curve. A high sensitivity plasma GL-1 assay with LLOQ at 0.1 μg/mL was developed and validated using delipidized plasma so that patient plasma concentrations that are below normal reference range can be measured accurately. The normal reference range was established from 120 healthy donors using this developed new method. Twenty-three Fabry patient plasma samples including baseline and post-investigation drug treatment samples were measured. All post-treatment samples showed GL-1 concentration below 2.0 μg/mL, indicating the utility of the reported high sensitivity assay using delipidized plasma for monitoring the plasma GL-1 biomarker level in patients.

Fabry's disease: an example of cardiorenal syndrome type 5

Cardiorenal syndrome type 5 (CRS-5) includes conditions where there is a simultaneous involvement of the heart and kidney from a systemic disorder. This is a bilateral organ cross talk. Fabry's disease (FD) is a devastating progressive inborn error of metabolism with lysosomal glycosphingolipid deposition in variety of cell types, capillary endothelial cells, renal, cardiac and nerve cells. Basic effect is absent or deficient activity of lysosomal exoglycohydrolase a-galactosidase A. Renal involvement consists of proteinuria, isosthenuria, altered tubular function, presenting in second or third decade leading to azotemia and end-stage renal disease in third to fifth decade mainly due to irreversible changes to glomerular, tubular and vascular structures, especially highlighted by podocytes foot process effacement. Cardiac involvement consists of left ventricular hypertrophy, right ventricular hypertrophy, arrhythmias (sinus node and conduction system impairment), diastolic dysfunction, myocardial ischemia, infarction, transmural replacement fibrosis, congestive heart failure and cardiac death. Management of FD is based on enzymatic replacement therapy and control of renal (with anti-proteinuric agents such as angiotensin-converting enzyme inhibitors-and/or angiotensin II receptor blockers), brain (coated aspirin, clopidogrel and statin to prevent strokes) and heart complications (calcium channel blockers for ischemic cardiomyopathy, warfarin and amiodarone or cardioverter device for arrhythmias).

Fabry Disease Biomarkers: Analysis of Urinary Lyso-Gb3 and Seven Related Analogs Using Tandem Mass Spectrometry

Fabry disease is an X-linked lysosomal storage disorder caused by the absence or reduction of the enzyme α-galactosidase A activity. Currently, globotriaosylsphingosine (lyso-Gb3 ) and globotriaosylceramide (Gb3 ) are used as biomarkers to diagnose and monitor Fabry patients. However, recent metabolomic studies have shown that several glycosphingolipids are also elevated in biological fluids of affected patients and may be related to disease manifestations. This unit describes a multiplex methodology targeting the analysis of urinary lyso-Gb3 and seven structurally related analogs. A solid-phase extraction process is performed, then lyso-Gb3 and its analogs are analyzed simultaneously with an internal standard by ultra-performance liquid chromatography (UPLC) coupled to a tandem mass spectrometry (MS/MS) system. This methodology can be useful for the diagnosis of Fabry patients, including patients with cardiac variant mutations, but also to monitor the efficacy of therapeutic interventions, considering that lyso-Gb3 analogs are more elevated than lyso-Gb3 itself in urine. © 2016 by John Wiley & Sons, Inc.

Maternal inhaled fluticasone propionate intake during pregnancy is detected in neonatal cord blood

BACKGROUND

Despite recommendations to use inhaled corticosteroids as treatment to control asthma during pregnancy, it is unknown whether inhaled fluticasone propionate (FP) reaches the fetus. Results & methodology: We collected maternal blood on the morning following delivery. FP was detected by ultra-performance LC-MS/MS (UPLC-MS/MS) in 9/17 asthmatic women using FP. Delay between last FP inhalation and maternal blood sampling ranged between 3 and 33 h and FP was detected in a range of 1.572-46.440 pg/ml. Among the nine offspring of these FP users, FP was detected in five cord blood samples. Delay between last predelivery FP inhalation and cord blood sampling ranged from 4 to 20 h and FP was detected in a range of 0.423-4.510 pg/ml.

CONCLUSION

Our findings demonstrate placental passage of inhaled FP.

A Novel Rapid MALDI-TOF-MS-Based Method for Measuring Urinary Globotriaosylceramide in Fabry Patients

Fabry disease is an X-linked lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in the accumulation of glycosphingolipids in various organs. Globotriaosylceramide (Gb3) and its isoforms and analogues have been identified and quantified as biomarkers of disease severity and treatment efficacy. The current study aimed to establish rapid methods for urinary Gb3 extraction and quantitation. Urine samples from 15 Fabry patients and 21 healthy control subjects were processed to extract Gb3 by mixing equal volumes of urine, methanol containing an internal standard, and chloroform followed by sonication and centrifugation. Thereafter, the lower phase was analyzed by MALDI-TOF MS and the relative peak areas of the internal standard and four major species of Gb3 determined. The results showed high reproducibility with intra- and inter-assay coefficients variation of 9.9% and 13.7%, respectively. The limit of detection was 0.15 ng/μL and the limit of quantitation was 0.30 ng/μL. Total urinary Gb3 levels in both genders of classic Fabry patients were significantly higher than in healthy controls (p < 0.0001). Gb3 levels in Fabry males were higher than in Fabry females (p = 0.08). We have established a novel assay for urinary total Gb3 that takes less than 15 min from start to finish. Graphical Abstract ᅟ.

Tandem mass spectrometry multiplex analysis of methylated and non-methylated urinary Gb3 isoforms in Fabry disease patients

BACKGROUND

Fabry disease is a lysosomal storage disorder leading to the accumulation of glycosphingolipids in biological fluids and tissues. Globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3) are currently used for Fabry screening and diagnosis. However, these biomarkers are not always increased in Fabry patients with residual enzyme activity. We recently identified 7 urinary methylated Gb3-related isoforms. The aims of this study were (1) to develop and validate a novel LC-MS/MS method for the relative quantification of methylated and non-methylated Gb3 isoforms normalized to creatinine, (2) to evaluate these biomarkers in Fabry patients and healthy controls, and (3) to assess correlations between biomarker urinary excretion with age, gender, treatment and genotype of patients.

METHODS

Urine samples from 150 Fabry patients and 95 healthy controls were analyzed. Samples were purified and injected in the tandem mass spectrometer working in positive electrospray ionization. Relative quantification was performed for 15 methylated and non-methylated Gb3 isoforms.

RESULTS

Significant correlations (p<0.001) were established between Gb3 isoform concentrations, gender and treatment. Five patients with the late-onset cardiac mutation p.N215S showed abnormal concentrations of methylated Gb3 isoforms compared to their non-methylated homologues.

CONCLUSIONS

Methylated Gb3 isoforms might be helpful urinary biomarkers for Fabry patients with late-onset cardiac variant mutations.

Variations in the GLA gene correlate with globotriaosylceramide and globotriaosylsphingosine analog levels in urine and plasma

Recent data have shown that lyso-Gb3, the deacylated derivative of globotriaosylceramide (Gb3), is possibly involved in the pathogenesis of Fabry disease (FD) and might be a clinically useful biomarker of its metabolic load. To test this hypothesis, we assayed Gb3 and lyso-Gb3 and related analogs in plasma and/or urine samples of 12 clinically well-characterized subjects carrying several different GLA variant alleles associated with a wide range of residual α-galactosidase A activities. Urinary Gb3 was measured by HPLC-MS/MS; plasma and urinary lyso-Gb3 and related analogs were measured by UPLC-MS/MS. Individual profiles of Gb3 and lyso-Gb3 and related analogs closely correlated with the phenotypic data for each subject, discerning the classical FD patient from the two patients carrying cardiac variants as well as those from all the others without FD. The lyso-Gb3 analog at m/z 836 was found at increased levels only in patients manifesting clinically severe heart disease, irrespective of the pathogenicity of the GLA variant they carried. This finding suggests that this lyso-Gb3 analog might be an earlier biomarker of progressive heart disease, non-specific of the FD cardiomyopathy. The possibility that urinary Gb3 is a specific marker of kidney involvement in FD deserves further study.

Metabolomic discovery of novel urinary galabiosylceramide analogs as Fabry disease biomarkers

Fabry disease is an X-linked, complex, multisystemic lysosomal storage disorder presenting marked phenotypic and genotypic variability among affected male and female patients. Glycosphingolipids, mainly globotriaosylceramide (Gb(3)) isoforms/analogs, globotriaosylsphingosine (lyso-Gb(3)) and analogs, as well as galabiosylceramide (Ga(2)) isoforms/analogs accumulate in the vascular endothelium, nerves, cardiomyocytes, renal glomerular and tubular epithelial cells, and biological fluids. The search for biomarkers reflecting disease severity and progression is still on-going. A metabolomic study using quadrupole time-of-flight mass spectrometry has revealed 22 galabiosylceramide isoforms/analogs in urine of untreated Fabry patients classified in seven groups according to their chemical structure: (1) Saturated fatty acid; (2) one extra double bond; (3) two extra double bonds; (4) hydroxylated saturated fatty acid; (5) hydroxylated fatty acid and one extra double bond; (6) hydrated sphingosine and hydroxylated fatty acid; (7) methylated amide linkage. Relative quantification of both Ga(2) and Gb(3) isoforms/analogs was performed. All these biomarkers are significantly more abundant in urine samples from untreated Fabry males compared with healthy male controls. A significant amount of Ga(2) isoforms/analogs, accounting for 18% of all glycosphingolipids analyzed (Ga(2) + Gb(3) and respective isoforms/analogs), were present in urine of Fabry patients. Gb(3) isoforms containing saturated fatty acids are the most abundant (60.9%) compared with 26.3% for Ga(2). A comparison between Ga(2) isoforms/analogs and their Gb(3) counterparts also showed that the proportion of analogs with hydroxylated fatty acids is significantly greater for Ga(2) (35.8%) compared with Gb(3) (1.9%). These results suggest different biological pathways involved in the synthesis and/or degradation of Gb(3) and Ga(2) metabolites.

Depletion of globosides and isoglobosides fully reverts the morphologic phenotype of Fabry disease

Fabry disease is a monogenic X-linked lysosomal storage disease caused by α-galactosidase A (αGalA) deficiency. Enzyme replacement therapy through administration of the missing αGalA is currently the only accepted therapeutic option. However, this treatment is connected to high costs, has ill-defined indication criteria and its efficacy is controversially discussed. Our aim was to explore the possibility of a novel targeted substrate reduction therapy for Fabry disease. Owing to the fact that αGalA-deficient humans and mice accumulate the same glycosphingolipids (i.e. globosides, galabiosylceramide and isoglobosides), αGalA-deficient mice were crossed with mice deficient in enzymes synthesizing these classes of glycosphingolipids (i.e. globotrihexosylceramide and isoglobotrihexosylceramide synthase, respectively). Functional heart and kidney tests were performed together with an extensive biochemical analysis of urine and serum in aged mice. Lysosomal storage was assessed by thin layer chromatography and electron microscopy. We showed that depletion of globosides was sufficient to fully abolish the storage of glycosphingolipids in heart, kidney and liver and was paralleled by a complete restoration of lysosomal morphology in these organs. In contrast, in dorsal root ganglia, a depletion of both globosides and isoglobosides was necessary to fully counteract the lysosomal storage. The deficiency in globosides and/or isoglobosides did not cause any adverse effects. We conclude that substrate reduction therapy through inhibition of the synthesis of globosides and isoglobosides represents a valuable therapeutic option for Fabry disease, all the more as globosides and isoglobosides seem to be dispensable.

The kidney in Fabry's disease

Fabry disease (FD) is an X-linked disease in which mutations of the GLA gene result in a deficiency of the enzyme α-galactosidase A and subsequent progressive, intralysosomal deposition of undegraded glycosphingolipid products, primarily globotriaosylceramide, in multiple organs. Progressive nephropathy is one of the main features of FD and is marked by an insidious development, with an overall rate of progression of chronic kidney disease (CKD) very similar to diabetic nephropathy. Untreated patients usually develop end stage renal disease in their 50s. The decline in renal function in FD is adversely affected by male gender, advanced CKD, hypertension and, in particular, severe proteinuria. Enzyme replacement therapy (ERT) has been shown to slow the progression of Fabry nephropathy. The current consensus is that ERT should be started in all men and women with signs of renal involvement.

Hemolytic uremic syndrome

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy defined by thrombocytopenia, nonimmune microangiopathic hemolytic anemia, and acute renal failure. The most frequent form is associated with infections by Shiga-like toxin-producing bacteria (STEC-HUS). Rarer cases are triggered by neuraminidase-producing Streptococcus pneumoniae (pneumococcal-HUS). The designation of aHUS is used to refer to those cases in which an infection by Shiga-like toxin-producing bacteria or S. pneumoniae can be excluded. Studies performed in the last two decades have documented that hyperactivation of the complement system is the pathogenetic effector mechanism leading to the endothelial damage and the microvascular thrombosis in aHUS. Recent data suggested the involvement of the complement system in the pathogenesis of STEC-HUS and pneumococcal-HUS as well. Clinical signs and symptoms may overlap among the different forms of HUS; however, pneumococcal-HUS and aHUS have a worse prognosis compared with STEC-HUS. Early diagnosis and identification of underlying pathogenetic mechanism allows instating specific support measures and therapies. In clinical trials in patients with aHUS, complement inhibition by eculizumab administration leads to a rapid and sustained normalization of hematological parameters with improvement in long-term renal function. This review summarizes current concepts about the epidemiological findings, the pathological and clinical aspects of STEC-HUS, pneumococcal-HUS, and aHUS, and their diagnosis and management.

Risk of death in heart disease is associated with elevated urinary globotriaosylceramide

Background

Elevated urinary globotriaosylceramide (Gb₃) has been considered a hallmark of Fabry disease, an X‐linked lysosomal disorder that is a risk factor for most types of heart disease.

Methods and Results

We screened 1421 consecutive patients with common forms of heart disease for Fabry disease by measuring urinary Gb₃ in whole urine using tandem mass spectrometry, α‐galactosidase A activity in dried blood spots, and we looked for GLA mutations by parallel sequencing of the whole gene (exons and introns) in pooled genomic DNA samples followed by Sanger sequencing verification. GLA variants were found in 13 patients. In the 1408 patients without GLA mutations, urinary Gb₃ levels were significantly higher in heart disease patients compared to 116 apparently healthy controls (median difference=10.0 ng/mL and P<0.001). Urinary lipid profiling showed that levels of 5 other lipids significantly distinguished between urine of patients with Fabry disease (n=7) and heart disease patients with elevated urinary Gb₃ (n=6). Sphingomyelin and Gb₃ levels were abnormal in the left ventricular wall of patients with ischemic heart failure. Elevated levels of urinary Gb₃ were independently associated with increased risk of death in the average follow‐up of 17 months (hazard ratio=1.59 for increase in Gb₃ of 200, 95% CI=1.36 and 1.87, and P<0.0001).

Conclusions

In heart disease patients who do not have Fabry disease or GLA gene mutations, a higher level of urinary Gb₃ is positively associated with near‐term mortality. The elevation of urinary Gb₃ and that of other lipids suggests that heart disease is associated with multiorgan lipid abnormalities.

Clinical Trial Registration

URL: clinicaltrials.gov. Unique Identifier: NCT01019629.

A metabolomic study to identify new globotriaosylceramide-related biomarkers in the plasma of Fabry disease patients

Fabry disease is an X-linked lysosomal storage disorder caused by a deficiency of the enzyme α-galactosidase A, which results in the progressive accumulation of glycosphingolipids. In addition to the two biomarkers, globotriaosylceramide (Gb3) and globotriaosylsphingosine (lyso-Gb3), which are routinely used for detection and high-risk screening of Fabry disease patients, novel urinary Gb3-related isoforms/analogues as well as newly defined lyso-Gb3 analogues in plasma and urine from Fabry patients have recently been described by our group. The aim of this study was to extend our recent analyses to identify and evaluate new potential Gb3-related biomarkers in the plasma of untreated male Fabry disease patients using a mass spectrometry metabolomic approach. A multivariate statistical analysis revealed five Gb3-related novel biomarkers in the plasma of male Fabry patients. Three of these new biomarkers correspond to Gb3, which has an extra double bond on the sphingosine with C16:0, C18:0, and C22:1 fatty acid chains. The fourth biomarker corresponds to a mixture of two structural isomers, the first with a d16:1 sphingosine and a C16:0 fatty acid and the second with a d18:1 sphingosine and a C14:0 fatty acid. To our knowledge, it is the first time that a Gb3 analogue with a d16:1 sphingosine moiety has been reported. In addition, this Gb3 analogue was also present in its methylated form. These biomarkers are part of a metabolic profile that may provide insight into the pathophysiology of Fabry disease.

Migalastat HCl reduces globotriaosylsphingosine (lyso-Gb3) in Fabry transgenic mice and in the plasma of Fabry patients

Fabry disease (FD) results from mutations in the gene (GLA) that encodes the lysosomal enzyme α-galactosidase A (α-Gal A), and involves pathological accumulation of globotriaosylceramide (GL-3) and globotriaosylsphingosine (lyso-Gb₃). Migalastat hydrochloride (GR181413A) is a pharmacological chaperone that selectively binds, stabilizes, and increases cellular levels of α-Gal A. Oral administration of migalastat HCl reduces tissue GL-3 in Fabry transgenic mice, and in urine and kidneys of some FD patients. A liquid chromatography-tandem mass spectrometry method was developed to measure lyso-Gb₃ in mouse tissues and human plasma. Oral administration of migalastat HCl to transgenic mice reduced elevated lyso-Gb₃ levels up to 64%, 59%, and 81% in kidney, heart, and skin, respectively, generally equal to or greater than observed for GL-3. Furthermore, baseline plasma lyso-Gb₃ levels were markedly elevated in six male FD patients enrolled in Phase 2 studies. Oral administration of migalastat HCl (150 mg QOD) reduced urine GL-3 and plasma lyso-Gb₃ in three subjects (range: 15% to 46% within 48 weeks of treatment). In contrast, three showed no reductions in either substrate. These results suggest that measurement of tissue and/or plasma lyso-Gb₃ is feasible and may be warranted in future studies of migalastat HCl or other new potential therapies for FD.

Urinary globotriaosylsphingosine-related biomarkers for Fabry disease targeted by metabolomics

Fabry disease is a lysosomal storage disorder caused by deficiency of α-galactosidase A, resulting in glycosphingolipid accumulation in organs and tissues, including plasma and urine. Two disease-specific Fabry biomarkers have been identified and quantified in plasma and urine: globotriaosylceramide (Gb(3)) and globotriaosylsphingosine (lyso-Gb(3)). The search continues for biomarkers that might be reliable indicators of disease severity and response to treatment. The main objective of this study was to target other urinary biomarkers using a time-of-flight mass spectrometry metabolomic approach. Urinary metabolites of 63 untreated Fabry patients and 59 controls were analyzed. A multivariate statistical analysis performed on a subset of male samples revealed seven novel Fabry biomarkers in urine, all lyso-Gb(3) analogues having modified sphingosine moieties. The empirical formulas of the sphingosine modifications were determined by exact mass measurements (- C(2)H(4), - C(2)H(4) + O, - H(2), - H(2) + O, + O, + H(2)O(2), + H(2)O(3)). We evaluated the relative concentration of lyso-Gb(3) and its seven analogues by measuring area counts for each analogue in all Fabry patients. All samples were normalized to creatinine. We found higher concentrations for males with Fabry disease compared to females. None of these biomarkers were detected in controls. To our knowledge, this is the first time that lyso-Gb(3)-related Fabry disease biomarkers are detected in urine.

A variant of unknown significance in the GLA gene causing diagnostic uncertainty in a young female with isolated hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is genetically heterogeneous, and largely caused by mutations in genes encoding sarcomere proteins. However, GLA mutations causing Fabry disease, an X-linked lysosomal storage disorder, may also present with isolated HCM. As HCM genetic testing panels are increasingly being used clinically, variants of unknown significance (VUS) are encountered, leading to challenges in interpretation. We present an illustrative case: a 10-year-old girl with isolated HCM who, on testing with a HCM multi-gene panel, was found to carry a maternally inherited p.W24R variant in GLA. Attempts to evaluate the significance of this variant, by direct biochemical testing of patient specimens, gave inconclusive results. Subsequent in vitro protein expression studies suggested that the variant is unlikely to be pathogenic. This case highlights diagnostic dilemmas that can be provoked by VUS in general, and specifically raises a question whether GLA sequencing should be included in first-line diagnostic testing for female children with isolated hypertrophic cardiomyopathy.

Globotriaosylceramide is correlated with oxidative stress and inflammation in Fabry patients treated with enzyme replacement therapy

Fabry disease is an X-linked inborn error of glycosphingolipid catabolism due to deficient activity of α-galactosidase A that leads to accumulation of the enzyme substrates, mainly globotriaosylceramide (Gb3), in body fluids and lysosomes of many cell types. Some pathophysiology hypotheses are intimately linked to reactive species production and inflammation, but until this moment there is no in vivo study about it. Hence, the aim of this study was to investigate oxidative stress parameters, pro-inflammatory cytokines and Gb3 levels in Fabry patients under treatment with enzyme replacement therapy (ERT) and finally to establish a possible relation between them. We analyzed urine and blood samples of patients under ERT (n=14) and healthy age-matched controls (n=14). Patients presented decreased levels of antioxidant defenses, assessed by reduced glutathione (GSH), glutathione peroxidase (GPx) activity and increased superoxide dismutase/catalase (SOD/CAT) ratio in erythrocytes. Concerning to the damage to biomolecules (lipids and proteins), we found that plasma levels of malondialdehyde (MDA) and protein carbonyl groups and di-tyrosine (di-Tyr) in urine were increased in patients. The pro-inflammatory cytokines IL-6 and TNF-α were also increased in patients. Urinary Gb3 levels were positively correlated with the plasma levels of IL-6, carbonyl groups and MDA. IL-6 levels were directly correlated with di-Tyr and inversely correlated with GPx activity. This data suggest that pro-inflammatory and pro-oxidant states occur, are correlated and seem to be induced by Gb3 in Fabry patients.