Fabry disease biomarkers in patients switched from enzyme-replacement therapy to migalastat oral chaperone therapy

Background: A biomarker profile was evaluated longitudinally in patients with Fabry disease switched from enzyme-replacement therapy (ERT) to migalastat. Methods: 16 Gb3 isoforms and eight lyso-Gb3 analogues were analyzed in plasma and urine by LC-MS/MS at baseline and at three different time points in naive participants and participants switching from either agalsidase α or β to migalastat. Results: 29 adult participants were recruited internationally (seven centers). The Mainz Severity Score Index and mean biomarker levels remained stable (p ≥ 0.05) over a minimum of 12 months compared with baseline following the treatment switch. Conclusion: In this cohort of patients with Fabry disease with amenable mutations, in the short term, a switch from ERT to migalastat did not have a marked effect on the average biomarker profile.

Late-onset and classic phenotypes of Fabry disease in males with the GLA-Thr410Ala mutation

OBJECTIVE

To present phenotypic characteristics and biomarkers of a family with the rare mutation Thr410Ala of the α-galactosidase A gene (T410A/GLA) causing Fabry disease (FD).

METHODS AND RESULTS

In a woman in her 60s with hypertrophic cardiomyopathy, T410A/GLA was found in screening for variants in 59 cardiomyopathy-related genes. Her son in his 40s, two granddaughters and two great grandsons carried T410A/GLA. The son had a history of hypertension and paroxysmal AF but no microalbuminuria or classic symptoms or signs of FD. Baseline α-galactosidase A enzyme (α-Gal A) activity varied from 0% to 26.5%. Cardiac MRI showed mild Fabry cardiomyopathy (FC). During 11 years of enzyme replacement therapy (ERT), FC progressed and he suffered sudden cardiac death in his 50s. The great grandsons with T410A/GLA had no active α-Gal A, high lyso-Gb₃ levels and normal cardiac imaging. They suffered from neuropathic pain and gastrointestinal symptoms and were started with ERT at the age under 10. Granddaughters with T410A/GLA had α-Gal A activities of 8-18 and 10% of normal. The older granddaughter in her 30s was diagnosed with incipient FC. Plasma lyso-Gb₃ analogues were elevated, markedly in the elder male with FC and moderately in the elder granddaughter. In young males with classic phenotype, plasma lyso-Gb₃ analogues were only slightly elevated.

CONCLUSIONS

The T410A/GLA mutation caused late-onset FD with progressive cardiomyopathy in elder male, and classic FD in young males of the same family. Varying levels of α-Gal A and lyso-Gb₃ analogues reflected variable phenotype of FD in the family.

Mass Spectrometry Analysis of Globotriaosylsphingosine and Its Analogues in Dried Blood Spots

Fabry disease (FD) is an X-linked lysosomal storage disorder where impaired α-galactosidase A enzyme activity leads to the intracellular accumulation of undegraded glycosphingolipids, including globotriaosylsphingosine (lyso-Gb₃) and related analogues. Lyso-Gb₃ and related analogues are useful biomarkers for screening and should be routinely monitored for longitudinal patient evaluation. In recent years, a growing interest has emerged in the analysis of FD biomarkers in dried blood spots (DBSs), considering the several advantages compared to venipuncture as a technique for collecting whole-blood specimens. The focus of this study was to devise and validate a UHPLC-MS/MS method for the analysis of lyso-Gb₃ and related analogues in DBSs to facilitate sample collection and shipment to reference laboratories. The assay was devised in conventional DBS collection cards and in Capitainer^®B blood collection devices using both capillary and venous blood specimens from 12 healthy controls and 20 patients affected with FD. The measured biomarker concentrations were similar in capillary and venous blood specimens. The hematocrit (Hct) did not affect the correlation between plasma and DBS measurements in our cohort (Hct range: 34.3-52.2%). This UHPLC-MS/MS method using DBS would facilitate high-risk screening and the follow-up and monitoring of patients affected with FD.

Multiplex Quantification of Plasma Biomarkers for Patients with Gaucher Disease Type 1

Gaucher disease (GD) is a lysosomal storage disorder caused by a deficiency of the enzyme beta-glucocerebrosidase. This leads to the accumulation of glycolipids in macrophages and ultimately results in tissue damage. Recent metabolomic studies highlighted several potential biomarkers in plasma specimens. In hopes of better understanding the distribution, importance, and clinical significance of these potential markers, a UPLC-MS/MS method was developed and validated to quantify lyso-Gb₁ and six related analogs (with the following modifications on the sphingosine moiety: -C₂ H₄ (-28 Da), -C₂ H₄ +O (-12 Da), -H₂ (-2 Da), -H₂ +O (+14 Da), +O (+16 Da), and +H₂ O (+18 Da)), sphingosylphosphorylcholine, and N-palmitoyl-O-phosphocholineserine in plasma specimens of treated and untreated patients. This 12-min UPLC-MS/MS method involves a purification step via solid-phase extraction followed by evaporation under nitrogen flow and resuspension in an organic mix compatible with HILIC chromatography. This method is currently used for research purposes and might be used for monitoring, prognostics, and follow-up. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.

Persistent hematopoietic polyclonality after lentivirus-mediated gene therapy for Fabry disease

The safety and efficacy of lentivirus-mediated gene therapy was recently demonstrated in five male patients with Fabry disease-a rare X-linked lysosomal storage disorder caused by GLA gene mutations that result in multiple end-organ complications. To evaluate the risks of clonal dominance and leukemogenesis, which have been reported in multiple gene therapy trials, we conducted a comprehensive DNA insertion site analysis of peripheral blood samples from the five patients in our gene therapy trial. We found that patients had a polyclonal integration site spectrum and did not find evidence of a dominant clone in any patient. Although we identified vector integrations near proto-oncogenes, these had low percentages of contributions to the overall pool of integrations and did not persist over time. Overall, we show that our trial of lentivirus-mediated gene therapy for Fabry disease did not lead to hematopoietic clonal dominance and likely did not elevate the risk of leukemogenic transformation.

Vitamin B-12 Intake from Dairy but Not Meat Is Associated with Decreased Risk of Low Vitamin B-12 Status and Deficiency in Older Adults from Quebec, Canada

BACKGROUND

Vitamin B-12 deficiency can result in irreversible neurologic damages. It is most prevalent among older adults (∼5%-15%), mainly due to impaired absorption. Vitamin B-12 bioavailability varies between food sources, so their importance in preventing deficiency may also vary.

OBJECTIVES

Using the NuAge Database and Biobank, we examined the associations between vitamin B-12 intake (total and by specific food groups) and low vitamin B-12 status and deficiency in older adults.

METHODS

NuAge-the Quebec Longitudinal Study on Nutrition and Successful Aging-included 1753 adults aged 67-84 y who were followed 4 y. Analytic samples comprised 1230-1463 individuals. Dietary vitamin B-12 intake was assessed annually using three 24-h dietary recalls. Vitamin B-12 status was assessed annually as low serum vitamin B-12 (<221 pmol/L), elevated urinary methylmalonic acid (MMA)/creatinine ratio (>2 μmol/mmol), and a combination of both (deficiency). Vitamin B-12 supplement users were excluded. Multilevel logistic regressions, adjusted for relevant confounders, were used.

RESULTS

Across all study years, 21.8%-32.5% of participants had low serum vitamin B-12, 12.5%-17.0% had elevated urine MMA/creatinine, and 10.1%-12.7% had deficiency. Median (IQR) total vitamin B-12 intake was 3.19 μg/d (2.31-4.37). Main sources were "dairy" and "meat, poultry, and organ meats." The ORs (95% CIs) in the fifth quintile compared with the first of total vitamin B-12 intake were as follows: for low serum vitamin B-12, 0.52 (0.37, 0.75; P-trend < 0.0001); for elevated urine MMA/creatinine, 0.63 (0.37, 1.08; P-trend = 0.091); and for vitamin B-12 deficiency, 0.38 (0.18, 0.79; P-trend = 0.006). Similarly, ORs (95% CIs) in the fourth quartile compared with the first of dairy-derived vitamin B-12 intake were 0.46 (0.32, 0.66; P-trend < 0.0001), 0.51 (0.30, 0.87; P-trend = 0.006), and 0.35 (0.17, 0.73; P-trend = 0.003), respectively. No associations were observed with vitamin B-12 from "meat, poultry, and organ meats."

CONCLUSIONS

Higher dietary vitamin B-12 intake, especially from dairy, was associated with decreased risk of low vitamin B-12 status and deficiency in older adults. Food groups might contribute differently at reducing risk of deficiency in older populations.

Quantitation of a Urinary Profile of Biomarkers in Gaucher Disease Type 1 Patients Using Tandem Mass Spectrometry

Gaucher disease is a rare inherited disorder caused by a deficiency of the lysosomal acid beta-glucocerebrosidase enzyme. Metabolomic studies by our group targeted several new potential urinary biomarkers. Apart from lyso-Gb₁, these studies highlighted lyso-Gb₁ analogs −28, −26, −12 (A/B), +2, +14, +16 (A/B), +30, and +32 Da, and polycyclic lyso-Gb₁ analogs 362, 366, 390, and 394 Da. The main objective of the current study was to develop and validate a robust UPLC-MS/MS method to study the urine distribution of these biomarkers in patients. Method: Urine samples were purified using solid-phase extraction. A 12 min UPLC-MS/MS method was developed. Results: Validation assays revealed high precision and accuracy for creatinine and lyso-Gb₁. Most lyso-Gb₁ analogs had good recovery rates and high intra- and interday precision assays. Biomarker-estimated LOD and LOQ levels ranged from 56–109 pM to 186–354 pM, respectively. Comparison between GD patients and healthy controls showed significant differences in most biomarker levels. Typically, treated GD patients presented lower biomarker levels compared to untreated patients. Conclusions: These data suggest that the metabolites investigated might be interesting GD biomarkers. More studies with a larger cohort of patients will be needed to better understand the clinical significance of these GD biomarkers.

ATP-binding cassette transporters mediate differential biosynthesis of glycosphingolipid species

The cytosolic-oriented glucosylceramide (GlcCer) synthase is enigmatic, requiring nascent GlcCer translocation to the luminal Golgi membrane to access glycosphingolipid (GSL) anabolic glycosyltransferases. The mechanism by which GlcCer is flipped remains unclear. To investigate the role of GlcCer-binding partners in this process, we previously made cleavable, biotinylated, photoreactive GlcCer analogs in which the reactive nitrene was closely apposed to the GlcCer head group, while maintaining a C16-acyl chain. GlcCer-binding protein specificity was validated for both photoprobes. Using one probe, XLB, here we identified ATP-binding cassette (ABC) transporters ABCA3, ABCB4, and ABCB10 as unfractionated microsomal GlcCer-binding proteins in DU-145 prostate tumor cells. siRNA knockdown (KD) of these transporters differentially blocked GSL synthesis assessed in toto and via metabolic labeling. KD of ABCA3 reduced acid/neutral GSL levels, but increased those of LacCer, while KD of ABCB4 preferentially reduced neutral GSL levels, and KD of ABCB10 reduced levels of both neutral and acidic GSLs. Depletion of ABCA12, implicated in GlcCer transport, preferentially decreased neutral GSL levels, while ABCB1 KD preferentially reduced gangliosides, but increased neutral GSL Gb3. These results imply that multiple ABC transporters may provide distinct but overlapping GlcCer and LacCer pools within the Golgi lumen for anabolism of different GSL series by metabolic channeling. Differential ABC family member usage may fine-tune GSL biosynthesis depending on cell/tissue type. We conclude that ABC transporters provide a new tool for the regulation of GSL biosynthesis and serve as potential targets to reduce selected GSL species/subsets in diseases in which GSLs are dysregulated.

Standardising clinical outcomes measures for adult clinical trials in Fabry disease: A global Delphi consensus

BACKGROUND

Recent years have witnessed a considerable increase in clinical trials of new investigational agents for Fabry disease (FD). Several trials investigating different agents are currently in progress; however, lack of standardisation results in challenges to interpretation and comparison. To facilitate the standardisation of investigational programs, we have developed a common framework for future clinical trials in FD.

METHODS AND FINDINGS

A broad consensus regarding clinical outcomes and ways to measure them was obtained via the Delphi methodology. 35 FD clinical experts from 4 continents, representing 3389 FD patients, participated in 3 rounds of Delphi procedure. The aim was to reach a consensus regarding clinical trial design, best treatment comparator, clinical outcomes, measurement of those clinical outcomes and inclusion and exclusion criteria. Consensus results of this initiative included: the selection of the adaptative clinical trial as the ideal study design and agalsidase beta as ideal comparator treatment due to its longstanding use in FD. Renal and cardiac outcomes, such as glomerular filtration rate, proteinuria and left ventricular mass index, were prioritised, whereas neurological outcomes including cerebrovascular and white matter lesions were dismissed as a primary or secondary outcome measure. Besides, there was a consensus regarding the importance of patient-related outcomes such as general quality of life, pain, and gastrointestinal symptoms. Also, unity about lysoGb3 and Gb3 tissue deposits as useful surrogate markers of the disease was obtained. The group recognised that cardiac T1 mapping still has potential but requires further development before its widespread introduction in clinical trials. Finally, patients with end-stage renal disease or renal transplant should be excluded unless a particular group for them is created inside the clinical trial.

CONCLUSION

This consensus will help to shape the future of clinical trials in FD. We note that the FDA has, coincidentally, recently published draft guidelines on clinical trials in FD and welcome this contribution.

Neonatal Urine Screening Program in the Province of Quebec: Technological Upgrade from Thin Layer Chromatography to Tandem Mass Spectrometry

The Quebec Neonatal Urine Screening Program was initiated in 1971 with overall screening inception of newborns in 1973. Forty-seven years later, over 3.5 million babies have been screened for up to 25 inborn errors of metabolism divided into two groups: (1) urea cycle disorders and organic acidurias; and (2) disorders of amino acid metabolism and transport. The main goal of this preventive genetic medicine program is the detection of treatable diseases before the onset of clinical symptoms. Urine specimens from 21-day-old babies are collected and dried on filter paper by parents at home. The participation is voluntary with a high compliance rate over the years (~90%). Specimens are analyzed by thin layer chromatography (TLC). The main objective of this evaluative research project was to assess the feasibility of a technological upgrade towards mass spectrometry. A 2.85-min flow injection method was devised, normal values established, and abnormal profiles confirmed using second-tier tests. The validated assays are sensitive, specific, and suitable for populational screening, as well as for high-risk screening laboratories. Triple H syndrome, which would not be detected in newborns by blood screening at two days of age was found to be positive in the urine of an affected patient.

Lentivirus-mediated gene therapy for Fabry disease

Enzyme and chaperone therapies are used to treat Fabry disease. Such treatments are expensive and require intrusive biweekly infusions; they are also not particularly efficacious. In this pilot, single-arm study (NCT02800070), five adult males with Type 1 (classical) phenotype Fabry disease were infused with autologous lentivirus-transduced, CD34⁺-selected, hematopoietic stem/progenitor cells engineered to express alpha-galactosidase A (α-gal A). Safety and toxicity are the primary endpoints. The non-myeloablative preparative regimen consisted of intravenous melphalan. No serious adverse events (AEs) are attributable to the investigational product. All patients produced α-gal A to near normal levels within one week. Vector is detected in peripheral blood and bone marrow cells, plasma and leukocytes demonstrate α-gal A activity within or above the reference range, and reductions in plasma and urine globotriaosylceramide (Gb₃) and globotriaosylsphingosine (lyso-Gb₃) are seen. While the study and evaluations are still ongoing, the first patient is nearly three years post-infusion. Three patients have elected to discontinue enzyme therapy.

Treatments for Fabry disease, an inherited lysosomal disorder caused by the deficiency of the enzyme alpha-galactosidase A, are not fully efficacious. Here the authors report a single-arm phase I trial of gene therapy with autologous, lentivirus-transduced, hematopoietic cells that express alpha-galactosidase A to demonstrate that this approach is safe in five patients with Fabry disease.

Identification of a Reliable Biomarker Profile for the Diagnosis of Gaucher Disease Type 1 Patients Using a Mass Spectrometry-Based Metabolomic Approach

Gaucher disease (GD) is a rare autosomal recessive multisystemic lysosomal storage disorder presenting a marked phenotypic and genotypic variability. GD is caused by a deficiency in the glucocerebrosidase enzyme. The diagnosis of GD remains challenging because of the large clinical spectrum associated with the disease. Moreover, GD biomarkers are often not sensitive enough and can be subject to polymorphic variations. The main objective of this study was to perform a metabolomic study using an ultra-performance liquid chromatography system coupled to a time-of-flight mass spectrometer to identify novel GD biomarkers. Following the analysis of plasma samples from patients with GD, and age- and gender-matched control samples, supervised statistical analyses were used to find the best molecules to differentiate the two groups. Targeted biomarkers were structurally elucidated using accurate mass measurements and tandem mass spectrometry. This metabolomic study was successful in highlighting seven biomarkers associated with GD. Fragmentation tests revealed that these latter biomarkers were lyso-Gb₁ (glucosylsphingosine) and four related analogs (with the following modifications on the sphingosine moiety: -C₂H₄, -H₂, -H₂+O, and +H₂O), sphingosylphosphorylcholine, and N-palmitoyl-O-phosphocholineserine. Based on the plasma biomarker distribution, we suggest the evaluation of this GD biomarker profile, which might facilitate early diagnosis, monitoring, and follow-up of patients.

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.

Assessing the role of glycosphingolipids in the phenotype severity of Fabry disease mouse model

Fabry disease is caused by deficient activity of α-galactosidase A, an enzyme that hydrolyzes the terminal α-galactosyl moieties from glycolipids and glycoproteins, and subsequent accumulation of glycosphingolipids, mainly globotriaosylceramide (Gb₃), globotriaosylsphingosine (lyso-Gb₃), and galabiosylceramide. However, there is no known link between these compounds and disease severity. In this study, we compared Gb₃ isoforms (various fatty acids) and lyso-Gb₃ analogs (various sphingosine modifications) in two strains of Fabry disease mouse models: a pure C57BL/6 (B6) background or a B6/129 mixed background, with the latter exhibiting more prominent cardiac and renal hypertrophy and thermosensation deficits. Total Gb₃ and lyso-Gb₃ levels in the heart, kidney, and dorsal root ganglion (DRG) were similar in the two strains. However, levels of the C20-fatty acid isoform of Gb₃ and particular lyso-Gb₃ analogs (+18, +34) were significantly higher in Fabry-B6/129 heart tissue when compared with Fabry-B6. By contrast, there was no difference in Gb₃ and lyso-Gb₃ isoforms/analogs in the kidneys and DRG between the two strains. Furthermore, using immunohistochemistry, we found that Gb₃ massively accumulated in DRG mechanoreceptors, a sensory neuron subpopulation with preserved function in Fabry disease. However, Gb₃ accumulation was not observed in nonpeptidergic nociceptors, the disease-relevant subpopulation that has remarkably increased isolectin-B4 (the marker of nonpeptidergic nociceptors) binding and enlarged cell size. These findings suggest that specific species of Gb₃ or lyso-Gb₃ may play major roles in the pathogenesis of Fabry disease, and that Gb₃ and lyso-Gb₃ are not responsible for the pathology in all tissues or cell types.

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.

Mass Spectrometry Evaluation of Biomarkers in the Vitreous Fluid in Gaucher Disease Type 3 with Disease Progression Despite Long-Term Treatment

Intraocular lesions have been infrequently reported in patients with Gaucher disease type 3 (GD3). We previously reported siblings with GD3 who responded well to the combination of enzyme replacement therapy (ERT) and substrate reduction therapy (SRT). Here we report progressive bilateral vitreous and preretinal deposits with declining visual acuity requiring bilateral vitrectomies in one of these siblings. These ocular manifestations had progressed despite combined ERT and SRT with improvement in visual acuity after vitrectomies. Vitrectomy fluid analysis performed for the first time by ultra-performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) identified a high concentration of glucosylceramide (GluCer) in the patient (262.842 nM) compared to a sample (0.428 nM from a patient without a lysosomal storage or known hereditary metabolic disorder). The GluCer detected in our patient was resolved into 12 different isoforms including two methylated ones. No evidence of galactosylceramide (GalCer) was detected. The development of these intraocular manifestations and their characterization by UPLC-MS/MS indicate a need for ongoing ophthalmologic evaluation of all GD patients and for new therapies that can cross the blood–retinal and blood–brain barriers for patients with GD and other neuropathic lysosomal storage disorders.

Elevated Inflammatory Plasma Biomarkers in Patients With Fabry Disease: A Critical Link to Heart Failure With Preserved Ejection Fraction

Background

Because systemic inflammation and endothelial dysfunction lead to heart failure with preserved ejection fraction, we characterized plasma levels of inflammatory and cardiac remodeling biomarkers in patients with Fabry disease (FD).

Methods and Results

Plasma biomarkers were studied in multicenter cohorts of patients with FD (n=68) and healthy controls (n=40). Plasma levels of the following markers of inflammation and cardiac remodeling were determined: tumor necrosis factor (TNF), TNF receptor 1 (TNFR1) and 2 (TNFR2), interleukin‐6, matrix metalloprotease‐2 (MMP‐2), MMP‐8, MMP‐9, galectin‐1, galectin‐3, B‐type natriuretic peptide (BNP), midregional pro–atrial natriuretic peptide (MR‐proANP), and globotriaosylsphingosine. Clinical profile, cardiac magnetic resonance imaging, and echocardiogram were reviewed and correlated with biomarkers. Patients with FD had elevated plasma levels of BNP, MR‐proANP, MMP‐2, MMP‐9, TNF, TNFR1, TNFR2, interleukin‐6, galectin‐1, globotriaosylsphingosine, and analogues. Plasma TNFR2, TNF, interleukin‐6, MMP‐2, and globotriaosylsphingosine were elevated in FD patients with left ventricular hypertrophy, whereas diastolic dysfunction correlated with higher BNP, MR‐proANP, and MMP‐2 levels. Patients with late gadolinium enhancement on cardiac magnetic resonance imaging had greater levels of BNP, MR‐proANP, TNFR1, TNFR2, and MMP‐2. Plasma BNP, MR‐proANP, MMP‐2, MMP‐8, TNF, TNFR1, TNFR2, galectin‐1, and galectin‐3 were elevated in patients with renal dysfunction. Patients undergoing enzyme replacement therapy who have more severe disease had higher MMP‐2, TNF, TNFR1, TNFR2, and globotriaosylsphingosine analogue levels.

Conclusions

Inflammatory and cardiac remodeling biomarkers are elevated in FD patients and correlate with disease progression. These features are consistent with a phenotype dominated by heart failure with preserved ejection fraction and suggest a key pathogenic role of systemic inflammation in FD.

Neonatal Mass Urine Screening Approach for Early Detection of Mucopolysaccharidoses by UPLC-MS/MS

Mucopolysaccharidoses (MPSs) are lysosomal storage disorders caused by deficiencies of enzymes involved in the catabolism of glycosaminoglycans (GAGs). Various treatments such as enzyme replacement therapy and/or hematopoietic stem cell transplant are available for MPSs. Early initiation of treatment improves the outcome and delays the onset of symptoms, highlighting the need for newborn screening for MPSs. The main objective of this project was to devise and validate a multiplex urine filter paper method for GAG analysis using a tandem mass spectrometry (MS/MS) approach to screen newborns for MPSs. Eluted urine samples from 21-day-old newborns were evaporated and a methanolysis reaction was performed. Samples were resuspended and analyzed using a UPLC-MS/MS system. A one-minute chromatographic method allowed the absolute quantification of heparan sulfate (HS), dermatan sulfate (DS), and creatinine. Method validation revealed high precision (< 9% relative standard deviation) and accuracy (< 7% bias) for all analytes. The reference values normalized to creatinine obtained by the analysis of five hundred 21-day-old newborn urine samples were 34.6 +/-6.2 mg/mmol of creatinine and 17.3 +/-3.9 mg/mmol of creatinine for HS and DS, respectively. We present a rapid and efficient method for populational newborn urine screening using MS/MS, which could also be applied to high-risk screening.

Mutation-specific Fabry disease patient-derived cell model to evaluate the amenability to chaperone therapy

BACKGROUND

Patients with Fabry disease (FD) and amenable mutations can be treated with the chaperone migalastat to restore endogenous α-galactosidase A (AGAL) activity. However, certain amenable mutations do not respond biochemically in vivo as expected. Here, we aimed to establish a patient-specific and mutation-specific cell model to evaluate the amenability to chaperone therapy in FD.

METHODS

Since current tests to determine amenability are limited to heterologous mutation expression in HEK293T cells with endogenous AGAL activity, we generated CRISPR/Cas9-mediated AGAL-deficient HEK293T cells as a basis for mutant overexpression. Furthermore, primary urinary cells from patients were isolated and immortalised as a patient-specific cell model system to evaluate the amenability to chaperone therapy.

RESULTS

Under treatment (>13 months), carriers of p.N215S (n=6) showed a significant reduction of plasma lyso-Gb3 (p<0.05). Lyso-Gb3 levels in carriers of p.L294S increased (p<0.05) and two patients developed severe albuminuria. Both missense mutations were amenable in wild-type HEK293T cells (p<0.05), but presented different responses in CRISPR/Cas9-mediated AGAL knockouts and immortalised urinary cells. Chaperone incubation resulted in increased AGAL activity (p<0.0001) and intracellular globotriaosylceramide (Gb3) reduction (p<0.05) in immortalised p.N215S cells but not in p.L294S and IVS2+1 G>A cells.

CONCLUSION

We conclude that repeated AGAL activity measurements in patients' white blood cells are mandatory to assess the in vivo amenability to migalastat. Plasma lyso-Gb3 might be an appropriate tool to measure the biochemical response to migalastat. Patients with low AGAL activities and increasing lyso-Gb3 levels despite in vitro amenability might not benefit sufficiently from chaperone treatment.

Altered immune phenotypes in subjects with Fabry disease and responses to switching from agalsidase alfa to agalsidase beta

Fabry disease (FD) is a rare X-linked genetic disorder caused by mutations in the GLA gene encoding the lysosomal enzyme, α-galactosidase A (α-gal A). The mutations lead to lack of or faulty enzyme causing accumulation of globotriaosylceramide (Gb3) and related glycosphingolipids including globotriaosylsphingosine (lyso-Gb₃). Treatment options for FD include enzyme replacement therapy. There are two different recombinant α-gal A enzymes, where agalsidase beta has been approved by FDA for use in the USA while both agalsidase beta and agalsidase alfa are being prescribed in many other countries. Several FD patients in the USA were switched to agalsidase alfa for a certain period of time due to supply shortage of agalsidase beta but were switched back to agalsidase beta upon availability. Due to the fact that some glycolipids may serve as antigens, various immune abnormalities have been associated with several lysosomal storage disorders (LSDs). In the present clinical study we evaluated alterations in peripheral immune cell subsets in patients with FD (n=27) compared to healthy control group (n=27). Patients with FD showed persistent T cell associated abnormalities, including skewed T helper to cytotoxic T cell ratio and elevated fraction of memory T cells and expression of activation markers on T cell subsets. Further, the study elucidated the effect of switching from agalsidase alfa to agalsidase beta on immune system as well as other clinical markers. While there was relative decrease in plasma lyso-Gb₃ as well as urine lyso-Gb₃ over time, their levels remained above the reference values. The immune abnormalities did not correlate with gender, age or lyso-Gb₃ levels, indicating that these persistent changes were inherent to FD irrespective of the extent of substrate accumulation.

Combined malonic and methylmalonic aciduria due to ACSF3 mutations: Benign clinical course in an unselected cohort

BACKGROUND

The clinical significance of combined malonic and methylmalonic aciduria due to ACSF3 deficiency (CMAMMA) is controversial. In most publications, affected patients were identified during the investigation of various complaints.

METHODS

Using a cross-sectional multicenter retrospective natural history study, we describe the course of all known CMAMMA individuals in the province of Quebec.

RESULTS

We identified 25 CMAMMA patients (6 months to 30 years old) with a favorable outcome regardless of treatment. All but one came to clinical attention through the Provincial Neonatal Urine Screening Program (screening on day 21 of life). Median methylmalonic acid (MMA) levels ranged from 107 to 857 mmol/mol creatinine in urine (<10) and from 8 to 42 μmol/L in plasma (<0.4); median urine malonic acid (MA) levels ranged from 9 to 280 mmol/mol creatinine (<5). MMA was consistently higher than MA. These findings are comparable to those previously reported in CMAMMA. Causal ACSF3 mutations were identified in all patients for whom genotyping was performed (76% of cases). The most common ACSF3 mutations in our cohort were c.1075G > A (p.E359K) and c.1672C > T (p.R558W), representing 38.2 and 20.6% of alleles in genotyped families, respectively; we also report several novel mutations.

CONCLUSION

Because our province still performs urine newborn screening, our patient cohort is the only one free of selection bias. Therefore, the favorable clinical course observed suggests that CMAMMA is probably a benign condition, although we cannot exclude the possibility that a small minority of patients may present symptoms attributable to CMAMMA, perhaps as a result of interactions with other genetic or environmental factors.

Contribution of tandem mass spectrometry to the diagnosis of lysosomal storage disorders

Tandem mass spectrometry (MS/MS) is a highly sensitive and specific technique. Thanks to the development of triple quadrupole analyzers, it is becoming more widely used in laboratories working in the field of inborn errors of metabolism. We review here the state of the art of this technique applied to the diagnosis of lysosomal storage disorders (LSDs) and how MS/MS has changed the diagnostic rationale in recent years. This fine technology brings more sensitive, specific, and reliable methods than the previous biochemical ones for the analysis of urinary glycosaminoglycans, oligosaccharides, and sialic acid. In sphingolipidoses, the quantification of urinary sphingolipids (globotriaosylceramide, sulfatides) is possible. The measurement of new plasmatic biomarkers such as oxysterols, bile acids, and lysosphingolipids allows the screening of many sphingolipidoses and related disorders (Niemann-Pick type C), replacing tedious biochemical techniques. Applied to amniotic fluid, a more reliable prenatal diagnosis or screening of LSDs is now available for fetuses presenting with antenatal manifestations. Applied to enzyme measurements, it allows high throughput assays for the screening of large populations, even newborn screening. The advent of this new method can modify the diagnostic rationale behind LSDs.

Globotriaosylsphingosine (Lyso-Gb3) as a biomarker for cardiac variant (N215S) Fabry disease

Fabry disease (FD) is a multi-systemic X-linked lysosomal disorder caused by the deficient activity of α-galactosidase-A enzyme, which leads to accumulation of glycosphingolipids in various body tissues. The N215S mutation is a known variant of FD, with a late onset cardiac phenotype. Consensus guidelines acknowledged the use of globotriaosylsphingosine (Lyso-Gb₃) as a diagnostic marker for classical FD but its utility for cardiac variant FD is not clear. We aim to characterize the clinical features and evaluate the diagnostic accuracy of plasma and urinary Lyso-Gb₃ levels in N215S cardiac variant FD patients. Thirty-four FD patients with the late-onset N215S cardiac variant mutation were enrolled along with 62 classical FD patients and 109 healthy controls. Plasma and urinary Lyso-Gb₃ and its analogues were analyzed by LC-MS/MS. Both FD males and females with N215S mutation showed Lyso-Gb₃ levels of (mean ± SEM) 9.7 ± 1.0 and 5.4 ± 0.8 nM, respectively. These levels were significantly higher than healthy control and lower than classical FD patients (p < 0.0001). Plasma Lyso-Gb₃ levels equal to or higher than 2.7 nM yielded a diagnostic sensitivity and specificity of 100% (AUC = 1, p < 0.0001). Cardiac involvement was frequent with 16/34 (47%) developing left ventricular hypertrophy. Three patients who underwent renal biopsy had the characteristic sphingolipid deposition in the podocytes while 6/19 (32%) had evidence of white matter changes or infarct on brain MRI. Taken together, cardiac variant N215S mutation is rather an attenuated form of classical FD. Plasma Lyso-Gb₃ is a diagnostic hallmark to differentiate N215S variant phenotype from subjects with no FD.

Analysis of globotriaosylceramide (Gb3) isoforms/analogs in unfractionated leukocytes, B lymphocytes and monocytes from Fabry patients using ultra-high performance liquid chromatography/tandem mass spectrometry

Fabry disease is an X-linked lysosomal storage disorder with marked variability in the phenotype and genotype. Glycosphingolipids such as globotriaosylceramide (Gb₃) isoforms/analogs, globotriaosylsphingosine (lyso-Gb₃) and analogs, and galabiosylceramide (Ga₂) isoforms/analogs may accumulate in biological fluids and different organs. The aims of this study were to: 1) develop/validate a novel UHPLC-MS/MS method for relative quantitation of Gb₃ in leukocytes (unfractionated white blood cells), B lymphocytes and monocytes; 2) evaluate these biomarkers in a cohort of Fabry patients and healthy controls; and 3) assess correlations between these biomarkers, treatment and genotype. Whole blood, plasma and urine samples from 21 Fabry patients and 20 healthy controls were analyzed. Samples were purified by liquid-liquid extraction and analyzed by UHPLC-MS/MS in positive electrospray ionization. Methylated Gb₃ isoforms were detected, showing that a methylation process occurs at the cellular level. Our results show that there were no significant differences in the distribution of the different Gb₃ isoforms/analogs in blood cells between Fabry patients and healthy controls. In leukocyte, Gb₃[(d18:1)(C14:0)], Gb₃[(d18:1)(C16:0)], Gb₃ [(d18:1)(C16:0)]Me, Gb₃ [(d18:1)(C16:1)], Gb₃ [(d18:1)(C18:0)], Gb₃ [(d18:1)(C18:1)], Gb₃ [(d18:1)(C20:1)], Gb₃ [(d18:1)(C24:2)], Gb₃ [(d18:1)(C26:1)] and total Gb₃ allowed good discrimination between male Fabry patients and male controls, patients having higher biomarker levels than controls. Regarding B lymphocytes and monocytes, the same tendency was observed without reaching statistical significance. A positive concordance between mutation types and biomarker levels in white blood cells was established. Our results might provide a deeper mechanistic comprehension of the underlying biochemical processes of Gb₃ biomarkers in white blood cells of Fabry patients.

The lysosomal enzyme alpha-Galactosidase A is deficient in Parkinson's disease brain in association with the pathologic accumulation of alpha-synuclein

The aberrant accumulation of alpha-synuclein (α-syn) is believed to contribute to the onset and pathogenesis of Parkinson's disease (PD). The autophagy-lysosome pathway (ALP) is responsible for the high capacity clearance of α-syn. ALP dysfunction is documented in PD and pre-clinical evidence suggests that inhibiting the ALP promotes the pathological accumulation of α-syn. We previously identified the pathological accumulation of α-syn in the brains of mice deficient for the soluble lysosomal enzyme alpha-Galactosidase A (α-Gal A), a member of the glycosphingolipid metabolism pathway. In the present study, we quantified α-Gal A activity and levels of its glycosphingolipid metabolites in postmortem temporal cortex specimens from control individuals and in PD individuals staged with respect to α-syn containing Lewy body pathology. In late-state PD temporal cortex we observed significant decreases in α-Gal A activity and the 46kDa "active" species of α-Gal A as determined respectively by fluorometric activity assay and western blot analysis. These decreases in α-Gal A activity/levels correlated significantly with increased α-syn phosphorylated at serine 129 (p129S-α-syn) that was maximal in late-stage PD temporal cortex. Mass spectrometric analysis of 29 different isoforms of globotriaosylceramide (Gb3), a substrate of α-Gal A indicated no significant differences with respect to different stages of PD temporal cortex. However, significant correlations were observed between increased levels of several Gb3 isoforms and with decreased α-Gal A activity and/or increased p129S-α-syn. Deacylated Gb3 (globotriaosylsphingosine or lyso-Gb3) was also analyzed in PD brain tissue but was below the limit of detection of 20pmol/g. Analysis of other lysosomal enzymes revealed a significant decrease in activity for the lysosomal aspartic acid protease cathepsin D but not for glucocerebrosidase (GCase) or cathepsin B in late-stage PD temporal cortex. However, a significant correlation was observed between decreasing GCase activity and increasing p129S-α-syn. Together our findings indicate α-Gal A deficiency in late-stage PD brain that correlates significantly with the pathological accumulation of α-syn, and further suggest the potential for α-Gal A and its glycosphingolipid substrates as putative biomarkers for PD.

Separation and Analysis of Lactosylceramide, Galabiosylceramide, and Globotriaosylceramide by LC-MS/MS in Urine of Fabry Disease Patients

Fabry disease is an X-linked lysosomal storage disorder caused by α-galactosidase A (α-GAL A) deficiency. This enzyme contributes to the cellular recycling of glycosphingolipids such as galabiosylceramide (Ga₂), globotriaosylceramide (Gb₃), and globotriaosylsphingosine (lyso-Gb₃) by hydrolyzing the terminal α-galactosyl moiety. Urine and plasma α-GAL A substrates are currently analyzed as biomarkers for the detection, monitoring, and follow-up of Fabry disease patients. The sensitivity of the analysis of Ga₂ is decreased by the co-analysis of its structural isomer, lactosylceramide (LacCer), which is not an α-GAL A substrate. A normal-phase ultraperformance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) methodology, allowing the baseline separation of 12 Ga₂ isoforms/analogues from their lactosylceramide counterparts, was developed and validated in urine. The method was multiplexed with the analysis of 12 Gb₃ isoforms/analogues having the same fatty acid moieties as those of Ga₂ for comparison, and with creatinine for sample normalization. Urine samples were studied from 34 untreated and 33 Fabry males treated by enzyme replacement therapy (ERT) and 54 untreated and 19 ERT-treated Fabry females, along with 34 male and 25 female healthy controls. The chromatographic separation of Ga₂ from LacCer increased the sensitivity of analysis, especially in women. One untreated Fabry female and two treated Fabry females presented abnormal levels of Ga₂ but normal levels of Gb₃, supporting the importance of analyzing Ga_2, in addition to Gb₃. Our results show that urine LacCer levels from females were significantly higher than those from males. Moreover, LacCer levels were not affected by Fabry disease for both males and females.

Lentivector Iterations and Pre-Clinical Scale-Up/Toxicity Testing: Targeting Mobilized CD34+ Cells for Correction of Fabry Disease

Fabry disease is a rare lysosomal storage disorder (LSD). We designed multiple recombinant lentivirus vectors (LVs) and tested their ability to engineer expression of human α-galactosidase A (α-gal A) in transduced Fabry patient CD34⁺ hematopoietic cells. We further investigated the safety and efficacy of a clinically directed vector, LV/AGA, in both ex vivo cell culture studies and animal models. Fabry mice transplanted with LV/AGA-transduced hematopoietic cells demonstrated α-gal A activity increases and lipid reductions in multiple tissues at 6 months after transplantation. Next we found that LV/AGA-transduced Fabry patient CD34⁺ hematopoietic cells produced even higher levels of α-gal A activity than normal CD34⁺ hematopoietic cells. We successfully transduced Fabry patient CD34⁺ hematopoietic cells with “near-clinical grade” LV/AGA in small-scale cultures and then validated a clinically directed scale-up transduction process in a GMP-compliant cell processing facility. LV-transduced Fabry patient CD34⁺ hematopoietic cells were subsequently infused into NOD/SCID/Fabry (NSF) mice; α-gal A activity corrections and lipid reductions were observed in several tissues 12 weeks after the xenotransplantation. Additional toxicology studies employing NSF mice xenotransplanted with the therapeutic cell product demonstrated minimal untoward effects. These data supported our successful clinical trial application (CTA) to Health Canada and opening of a “first-in-the-world” gene therapy trial 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.

High-Risk Screening of Fabry Disease: Analysis of Fifteen Urinary Methylated and Non-Methylated Gb3 Isoforms Using Tandem Mass Spectrometry

Fabry disease is a multisystemic, X-linked lysosomal storage disorder caused by mutations in the GLA gene, leading to α-galactosidase A deficiency and resulting in the accumulation of glycosphingolipids in different tissues and biological fluids. Glycosphingolipid biomarkers, such as globotriaosylceramide (Gb₃ ) isoforms, globotriaosylsphingosine (lyso-Gb₃ ) and related analogs, and galabiosylceramide (Ga₂ ) isoforms and analogs, are found to be abnormally increased in urine and in plasma of Fabry patients and have the potential to be used as specific biomarkers of the disease. This unit presents a protocol for the relative quantification of fifteen urinary isoforms of Gb₃ analyzed simultaneously with creatinine by ultra-performance liquid chromatography (UPLC) coupled to tandem mass spectrometry (MS/MS). In order to purify urine samples, a liquid-liquid extraction is performed and samples are analyzed by MS/MS in positive electrospray ionization mode. These biomarkers are useful for screening, diagnosis, and long-term monitoring of Fabry disease patients. We have shown that the methylated Gb₃ isoforms are particularly useful for screening Fabry patients who present with late-onset cardiac variant mutations. © 2016 by John Wiley & Sons, Inc.

Tandem Mass Spectrometry Quantitation of Lyso-Gb3 and Six Related Analogs in Plasma for Fabry Disease Patients

Fabry disease is an X-linked lysosomal storage disorder, caused by a deficit in α-galactosidase A enzyme activity, leading to the storage of sphingolipids such as globotriaosylsphingosine (lyso-Gb3 ), globotriaosylceramide (Gb3 ), and galabiosylceramide (Ga2 ) in organs, tissues and biological fluids. A recent metabolomic study performed in plasma revealed lyso-Gb3 analogs as novel Fabry disease biomarkers. These molecules correspond to lyso-Gb3 with different chemical modifications on the sphingosine chain (-C2 H4 , -H2 , +O, +H2 O, +H2 O2, and +H2 O3 ). An ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed and validated for the multiplex analysis of lyso-Gb3 and its 6 analogs in plasma. The samples are prepared by solid phase extraction using mixed-mode strong cation exchange (MCX) cartridges. An in-house synthesized N-glycinated lyso-Gb3 derivative was used for the internal standard. The limits of detection (LODs) measured for lyso-Gb3 and its analogs ranged from 0.06 to 0.29 nM. © 2016 by John Wiley & Sons, Inc.

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.

Diagnosis of late-onset Pompe disease and other muscle disorders by next-generation sequencing

Background

Late-onset Pompe disease (LOPD) is a rare treatable lysosomal storage disorder characterized by progressive lysosomal glycogen accumulation and muscle weakness, with often a limb-girdle pattern. Despite published guidelines, testing for LOPD is often overlooked or delayed in adults, owing to its low frequency compared to other muscle disorders with similar muscle patterns. Next-generation sequencing has the capability to test concurrently for several muscle disorders. This could potentially lead to increased diagnosis of LOPD, disorders with non-specific muscle weakness or atypical patients.

Methods

We developed a gene panel to further study its clinical utility in a cohort of patients with suspected muscle disorders. We designed a gene panel to analyze the coding sequences and splice site junctions of GAA causing LOPD, along with 77 other genes causing muscle disorders with overlapping phenotypes.

Results

At a median coverage of ~200X (sequences per base), all GAA exons were successfully covered with >20X and only 0.3 % of exons across all genes were <20X. The panel showed an excellent sensitivity (100 %) and specificity (98 %) across all selected genes, using known variations in Pompe patients and controls. We determined its clinical utility by analyzing 34 patients with suspected muscle disorders of undetermined etiology and various muscle patterns, who were referred or followed in neuromuscular and genetics clinics. A putative diagnosis was found in up to 32 % of patients. The gene panel was instrumental in reaching a diagnosis in atypical patients, including one LOPD case. Acid alpha-glucosidase activity was used to confirm the molecular results in all patients.

Conclusion

This work highlights the high clinical utility of gene panels in patients with suspected muscle disorders and its potential to facilitate the diagnosis of patients showing non-specific muscle weakness or atypical phenotypes. We propose that gene panels should be used as a first-tier test in patients with suspected muscle disorders of undetermined etiology, which could further increase overall diagnosis of muscle conditions, and potentially reduce diagnostic delay. Further studies are necessary to determine the impact of first-tier gene panels on diagnostic delay and on treatment outcome for LOPD.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-016-0390-6) contains supplementary material, which is available to authorized users.

Tandem Mass Spectrometry Multiplex Analysis of Glucosylceramide and Galactosylceramide Isoforms in Brain Tissues at Different Stages of Parkinson Disease

Previous studies demonstrated that Parkinson disease (PD) is associated with a decreased activity of the glucocerebrosidase (GCase) enzyme in brain tissues. The objective of this study was to determine if GCase deficiency is associated with the accumulation of its glucosylceramide (GluCer) substrate in PD brain tissues. An ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed, optimized, and validated for the multiplex analysis of GluCer isoforms (C18:0, C20:0, C22:0, C24:1, and C24:0) in brain tissue samples. These molecules were chromatographically separated from their isobaric galactosylceramide (GalCer) counterparts using normal phase chromatography. The analysis was performed by tandem mass spectrometry in the multiple reaction monitoring (MRM) acquisition mode. Limits of detection ranging from 0.4 to 1.1 nmol/g brain tissue were established for the different GluCer isoforms analyzed. For the first time, GluCer isoform levels were analyzed in temporal cortex brain tissue samples from 26 PD patients who were divided into three PD disease stages (IIa, III, and IV) according to the Unified Staging System for Lewy Body Disorders. These specimens were compared with brain tissue samples from 12 controls and 6 patients with Incidental Lewy Body Disease. No significant GluCer concentration differences were observed between the 5 sample groups. The GluCer isoform levels were also normalized with their matching GalCer isoforms. The normalized results showed a trend for GluCer levels which increased with PD severity. However, the differences observed between the groups were not significant, owing likely to the high standard deviations measured.

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.

Sulfatide Analysis by Mass Spectrometry for Screening of Metachromatic Leukodystrophy in Dried Blood and Urine Samples

BACKGROUND

Metachromatic leukodystrophy (MLD) is an autosomal recessive disorder caused by deficiency in arylsulfatase A activity, leading to accumulation of sulfatide substrates. Diagnostic and monitoring procedures include demonstration of reduced arylsulfatase A activity in peripheral blood leukocytes or detection of sulfatides in urine. However, the development of a screening test is challenging because of instability of the enzyme in dried blood spots (DBS), the widespread occurrence of pseudodeficiency alleles, and the lack of available urine samples from newborn screening programs.

METHODS

We measured individual sulfatide profiles in DBS and dried urine spots (DUS) from MLD patients with LC-MS/MS to identify markers with the discriminatory power to differentiate affected individuals from controls. We also developed a method for converting all sulfatide molecular species into a single species, allowing quantification in positive-ion mode upon derivatization.

RESULTS

In DBS from MLD patients, we found up to 23.2-fold and 5.1-fold differences in total sulfatide concentrations for early- and late-onset MLD, respectively, compared with controls and pseudodeficiencies. Corresponding DUS revealed up to 164-fold and 78-fold differences for early- and late-onset MLD patient samples compared with controls. The use of sulfatides converted to a single species simplified the analysis and increased detection sensitivity in positive-ion mode, providing a second option for sulfatide analysis.

CONCLUSIONS

This study of sulfatides in DBS and DUS suggests the feasibility of the mass spectrometry method for newborn screening of MLD and sets the stage for a larger-scale newborn screening pilot study.

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.

Assessment of urinary metabolite excretion after rat acute exposure to perfluorooctanoic acid and other peroxisomal proliferators

Perfluorooctanoic acid (PFOA) is a persistent environmental contaminant. Activation of the peroxisome proliferator activated receptor alpha (PPARα) resulting from exposure to PFOA has been extensively studied in rodents. However, marked differences in response to peroxisome proliferators prevent extrapolation of rodent PPARα activation to human health risks and additional molecular mechanisms may also be involved in the biological response to PFOA exposure. To further explore the potential involvement of such additional pathways, the effects of PFOA exposure on urinary metabolites were directly compared with those of other well-known PPARα agonists. Male rats were administered PFOA (10, 33, or 100 mg/kg/d), fenofibrate (100 mg/kg/d), or di(2-ethylhexyl) phthalate (100 mg/kg/d) by gavage for 3 consecutive days and allowed to recover for 4 days, and overnight urine was collected. Greater urinary output was observed exclusively in PFOA-treated rats as the total fraction of PFOA excreted in urine increased with the dose administered. Assessment of urinary metabolites (ascorbic acid, quinolinic acid, 8-hydroxy-2'-deoxyguanosine, and malondialdehyde) provided additional information on PFOA's effects on hepatic glucuronic acid and tryptophan-nicotinamide adenine dinucleotide (NAD) pathways and on oxidative stress, whereas increased liver weight and palmitoyl-CoA oxidase activity indicative of PPARα activation and peroxisomal proliferation persisted up to day five after the last exposure.

Glycation of fetal hemoglobin reflects hyperglycemia exposure in utero

OBJECTIVE

The lifetime risk of metabolic diseases in offspring of women with gestational diabetes mellitus (GDM) depends, at least in part, on the impact of glycemic fetal programming. To quantify this impact, we have developed and validated a unique mass spectrometry method to measure the percentage of glycated hemoglobin in cord blood.

RESEARCH DESIGN AND METHODS

This case-control study includes 37 GDM women and 30 pregnant women with normal glucose tolerance (NGT).

RESULTS

Glycation of the α-chain (Glα) was higher in neonates from GDM (2.32 vs. 2.20%, P < 0.01). Glα strongly correlated with maternal A1C measured at delivery in the overall cohort (r = 0.67, P < 0.0001) as well as in each group (GDM: r = 0.66, P < 0.0001; NGT: r = 0.50, P = 0.01).

CONCLUSIONS

Thus, Glα may reflect hyperglycemic exposure during the last weeks of fetal development. Future studies will confirm Glα is a predictive biomarker of prenatally programmed lifetime metabolic health and disease.