Patients with Gaucher disease display systemic elevation of ACE2, which is impacted by therapy status and genotype.

Gaucher disease (GD) has a high carrier rate among Ashkenazi Jews.The most common disease-causing variant in this population N370S, is also prevalent pan-ethnically. This has led to speculations of some protective effect for carriers of this variant. During the recent COVID-19 pandemic, GD patients reportedly had a surprisingly low infection rate and mild symptoms considering their disease status. As SARS-CoV-2 gains entry into the cell via membrane-bound angiotensin-converting enzyme 2 (ACE2), we speculated that differences in levels of soluble ACE2 in GD patients could contribute to this protective state. While ACE is known to be elevated in GD, to our knowledge, ACE2 levels have not been explored. We measured serum and macrophage-bound levels of ACE and ACE2 by ELISA and western blot, respectively, in GD patients and age- and sex-matched controls. Our results reveal a significant elevation of both serum and macrophage-bound ACE and ACE2 in GD patients compared to healthy controls. This elevation appears to be mitigated by GD treatment. Moreover, the most robust ACE2 elevation was observed in N370S homozygotes, and was not effected by treatment. Since coronaviruses use the ACE2 receptor as a gateway for host cell entry, we speculate that elevated circulating ACE2 may serve as a decoy. This might explain the observed mild infections in GD patients during the COVID-19 pandemic.

Increased glucosylsphingosine levels and Gaucher disease in GBA1-associated Parkinson's disease.

INTRODUCTION: Gaucher's disease (GD) is caused by biallelic mutations in the GBA1 gene, leading to reduced glucocerebrosidase (GCase) activity and substrate (glucosylceramide and glucosylsphingosine, GlcSph) accumulation. GBA1 variant carriers are at risk of Parkinson's disease (PD), but only those with biallelic mutations cross the threshold of GCase reduction, leading to substrate accumulation and GD. The link between GBA1 mutations, GD and PD is not fully understood. Here we aimed at reporting the results of a large PD population screening with dried blood spot tests for GD. METHODS: We measured GCase activity and GlcSph levels in 1344 PD patients with dried blood spot tests, and performed GBA1 genetic sequencing. RESULTS: While the GCase activity was reduced in GBA1-PD carriers compared to wild type PD, GlcSph was increased in GBA1-PD compared to GBA1-controls, regardless of the underlying type of GBA1 variant. 13.6 % and 0.4 % of PD patients had mono- or biallelic GBA1 mutations respectively. GCase deficiency, lipid accumulation and clinical manifestations of GD was detected in five PD patients with biallelic GBA1 mutations, of whom four had a risk combined with a GD causing variant. CONCLUSIONS: GlcSph appearing higher in PD may represent a reliable biomarker of the disease and deserves to be further investigated. This study highlights the importance of screening PD patients for possible underlying GD, which is a treatable condition that should not be missed. We diagnosed GD cases carrying a "risk" variant in one allele, which is an unprecedented finding deserving further investigation.

GPNMB Biomarker Levels in GBA1 Carriers with Lewy Body Disorders.

BACKGROUND: The GPNMB single-nucleotide polymorphism rs199347 and GBA1 variants both associate with Lewy body disorder (LBD) risk. GPNMB encodes glycoprotein nonmetastatic melanoma protein B (GPNMB), a biomarker for GBA1-associated Gaucher's disease. OBJECTIVE: The aim of this study was to determine whether GPNMB levels (1) differ in LBD with and without GBA1 variants and (2) associate with rs199347 genotype. METHODS: We quantified GPNMB levels in plasma and cerebrospinal fluid (CSF) from 124 individuals with LBD with one GBA1 variant (121 plasma, 14 CSF), 631 individuals with LBD without GBA1 variants (626 plasma, 41 CSF), 9 neurologically normal individuals with one GBA1 variant (plasma), and 2 individuals with two GBA1 variants (plasma). We tested for associations between GPNMB levels and rs199347 or GBA1 status. RESULTS: GPNMB levels associate with rs199347 genotype in plasma (P = 0.022) and CSF (P = 0.007), but not with GBA1 status. CONCLUSIONS: rs199347 is a protein quantitative trait locus for GPNMB. GPNMB levels are unaltered in individuals carrying one GBA1 variant. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Endocrinological and metabolic profile of Gaucher disease patients treated with enzyme replacement therapy.

OBJECTIVES: Gaucher disease (GD) is a lysosomal storage disease caused by glucocerebrosidase (GCase) enzyme deficiency. Gaucher cells transformed from the macrophages by progressive sphingolipid accumulation and infiltrate bone marrow, spleen, liver, and other organs. The accumulation of substrate causes inflammation, compromised cellular homeostasis, and disturbed autophagy. It has been hypothesized that this proinflammatory state of GD leads cytokines and chemokines release. As a result of inflammatory process, the cellular dysfunction caused by disruption of cellular signaling, organelle dysfunction, or autoimmune antibodies may affect endocrine profile of GD patients such as hormone levels, lipid profile, and bone mineral density status. METHODS: A total of 13 patients confirmed to have GD, 12 non-neuronopathic type and one subacute neuronopathic type, were enrolled in our study. RESULTS: The median treatment duration in the enzyme therapy was 13.33 years (9-26 years). At least one endocrinological abnormality was detected in blood tests of nine patients. Hyperinsulinism was the most common finding although fasting blood glucose levels HgbA1c levels were normal in all patients. Two patients had osteopenia, and osteoporosis was detected in two patients. Low HDL levels were detected in six patients, but HDL levels below 23 mg/dL associated with disease severity have been detected in two patients who have not receiving enzyme replacement therapy. None of patients had thyroidal dysfunction. CONCLUSIONS: This study had revealed endocrinological abnormalities in GD patients that have not led any severe morbidity in our patients. However, thyroid hormone abnormalities, insulin resistance, or lipid profile abnormalities may cause unpredictable comorbidities. Endocrinological assessment in GD patients in routine follow-up may prevent possible clinical manifestation in long term as well as can define efficacy of ERT on endocrine abnormalities.

Glycoprotein non-metastatic protein B (GPNMB) plasma values in patients with chronic visceral acid sphingomyelinase deficiency.

Acid sphingomyelinase deficiency (ASMD) is a rare LSD characterized by lysosomal accumulation of sphingomyelin, primarily in macrophages. With the recent availability of enzyme replacement therapy, the need for biomarkers to assess severity of disease has increased. Glycoprotein non-metastatic protein B (GPNMB) plasma levels were demonstrated to be elevated in Gaucher disease. Given the similarities between Gaucher disease and ASMD, the hypothesis was that GPNMB might be a potential biochemical marker for ASMD as well. Plasma samples of ASMD patients were analyzed and GPNMB plasma levels were compared to those of healthy volunteers. Visceral disease severity was classified as severe when splenic, hepatic and pulmonary manifestations were all present and as mild to moderate if this was not the case. Median GPNMB levels in 67 samples of 19 ASMD patients were 185 ng/ml (range 70-811 ng/ml) and were increased compared to 10 healthy controls (median 36 ng/ml, range 9-175 ng/ml, p < 0.001). Median plasma GPNMB levels of ASMD patients with mild to moderate visceral disease compared to patients with severe visceral disease differed significantly and did not overlap (respectively 109 ng/ml, range 70-304 ng/ml and 325 ng/ml, range 165-811 ng/ml, p < 0.001). Correlations with other biochemical markers of ASMD (i.e. chitotriosidase activity, CCL18 and lysosphingomyelin, respectively R = 0.28, p = 0.270; R = 0.34, p = 0.180; R = 0.39, p = 0.100) and clinical parameters (i.e. spleen volume, liver volume, diffusion capacity and forced vital capacity, respectively R = 0.59, p = 0.061, R = 0.5, p = 0.100, R = 0.065, p = 0.810, R = -0.38, p = 0.160) could not be established within this study. The results of this study suggest that GPNMB might be suitable as a biomarker of visceral disease severity in ASMD. Correlations between GPNMB and biochemical or clinical markers of ASMD and response to therapy have to be studied in a larger cohort.

Contribution of Glucosylsphingosine (Lyso-Gb1) to Treatment Decisions in Patients with Gaucher Disease.

Glucosylsphingosine (lyso-Gb1), the deacylated form of glucocerebroside, was shown to be the most specific and sensitive biomarker for diagnosing Gaucher disease (GD). The aim of this study is to assess the contribution of lyso-Gb1 at the time of diagnosis for treatment decisions in naïve patients with GD. Newly diagnosed patients from July 2014 to November 2022 were included in this retrospective cohort study. The diagnosis was done by sending a dry blood spot (DBS) sample for GBA1 molecular sequencing and lyso-Gb1 quantification. Treatment decisions were based on symptoms, signs, and routine laboratory tests. We diagnosed 97 patients (41 males), both type 1 (n = 87), and neuronopathic (n = 10). The median (range) age at diagnosis was 22 (1-78), with 36 children. In 65 patients, GD-specific therapy was started with a median (range) lyso-Gb1, 337 (60-1340) ng/mL, significantly higher than in patients who did not go on to treatment, 153.5 (9-442) ng/mL. Using a receiver operating characteristic (ROC) analysis, a cutoff of lyso-Gb1 > 250 ng/mL was associated with treatment with a sensitivity of 71% and specificity of 87.5%. Predictors of treatment were thrombocytopenia, anemia, and elevated lyso-Gb1 (>250 ng/mL). In conclusion, lyso-Gb1 levels contribute to the medical decision related to the initiation of treatment, mainly among mildly affected newly diagnosed patients. For patients with a severe phenotype, as for all patients, the main value of lyso-Gb1 would be to monitor response to therapy. The variable methodology and differences in the units of lyso-Gb1 measurements between laboratories prevent the adaptation of the exact cut-off we found in general practice. However, the concept is that a significant elevation, i.e., a several-fold increase from the diagnostic lyso-Gb1 cutoff, is related to a more severe phenotype and, accordingly, to the decision regarding the initiation of GD-specific therapy.

Measurement of glycosylated ferritin with Concanavalin A: Assay design, optimization and validation.

INTRODUCTION: Ferritin is the major iron-storage glycoprotein found in all tissues. Ferritin glycosylation can be assessed by the differential affinities of ferritin glycoforms for Concanavalin A (ConA), a lectin. The fraction of serum ferritin bound to ConA is called "glycosylated ferritin" (GF). Low GF reflects macrophagic activation and is an essential biomarker used in adult-onset Still's disease (AOSD), macrophage activation syndrome (MAS) and Gaucher disease diagnosis and therapeutic management. To date, no complete assay description and method validation according to the ISO 15189 standard has been published. This study aimed to describe and validate our method used for GF measurement and describe GF values observed in patients. MATERIALS AND METHODS: Ferritin glycoforms were separated based on their affinities for ConA using commercially available TRIS-barbital buffer, Sepharose and ConA/Sepharose 4B gels. Ferritin concentrations were measured on the Siemens Dimension Vista 1500®. We analysed 16,843 GF values obtained between 2000 and 2021 from our database of patients. RESULTS: Optimal separation of ferritin glycoforms was obtained by 15-min incubation of serum with ConA/Sepharose at pH 8. The optimized volume were 0.4 mL for total serum ferritin (TSF) 30-1000 µg/L and 0.5 mL for TSF 1000-2500 µg/L. Serum with higher TSF should be pre-diluted in the TRIS-barbital buffer. Reproducibility of ferritin measurement in the TRIS-barbital buffer matrix was excellent (intra-assay CV < 1%; inter-assay CV < 4%). Reproducibility of GF assay was good (intra-assay CV < 10% for low and high ferritin samples, respectively; and inter-assay CV < 10%). Inter-operator variability was 21.6% for GF < 20%. Ferritin was stable for up to 3 days in the TRIS-barbital buffer. An inter-laboratory exchange program conducted with another French hospital showed good agreement between results. In our database, <20% GF levels were scarce, compatible with the low prevalence of Still's disease, MAS, and Gaucher disease. The 95% confidence interval for GF was [26-58]%, lower than values described in the literature for healthy individuals. CONCLUSION: Thanks to good performances, this technique can become readily available for laboratories servicing patients with AOSD, MAS (including severe COVID-19 patients) and Gaucher disease patients.

Quantitation of a plasma biomarker profile for the early detection of Gaucher disease type 1 patients.

Aim: Gaucher disease (GD) is caused by a deficiency of the lysosomal enzyme acid ß-glucocerebrosidase. Recent metabolomic studies highlighted several new metabolites increased in the plasma of GD patients. We aimed to develop and validate a UPLC-MS/MS method allowing a relative quantitation of lyso-Gb1 and lyso-Gb1 analogs -28, -12, -2, +14, +16 and +18 Da in addition to sphingosylphosphorylcholine, N-palmitoyl-O-phosphocholine to study potential correlations with clinical manifestations. Methodology & results: Following solid-phase extraction, plasma samples were evaporated and resuspended in 100 µl of resuspension solution. Three microliter is injected into the UPLC-MS/MS for analysis. Conclusion: All biomarkers studied were increased in GD patients. Significant correlations were observed between specific analogs and hematological, and visceral complications, as well as overall disease severity.

Gaucher Disease Diagnosis Using Lyso-Gb1 on Dry Blood Spot Samples: Time to Change the Paradigm?

For years, the gold standard for diagnosing Gaucher disease (GD) has been detecting reduced ß-glucocerebrosidase (GCase) activity in peripheral blood cells combined with GBA1 mutation analysis. The use of dried blood spot (DBS) specimens offers many advantages, including easy collection, the need for a small amount of blood, and simpler transportation. However, DBS has limitations for measuring GCase activity. In this paper, we recount our cross-sectional study and publish seven years of experience using DBS samples and levels of the deacylated form of glucocerebroside, glucosylsphingosine (lyso-Gb1), for GD diagnosis. Of 444 screened subjects, 99 (22.3%) were diagnosed with GD at a median (range) age of 21 (1-78) years. Lyso-Gb levels for genetically confirmed GD patients vs. subjects negative to GD diagnosis were 252 (9-1340) ng/mL and 5.4 (1.5-16) ng/mL, respectively. Patients diagnosed with GD1 and mild GBA1 variants had lower median (range) lyso-Gb1, 194 (9-1050), compared to GD1 and severe GBA1 variants, 447 (38-1340) ng/mL, and neuronopathic GD, 325 (116-1270) ng/mL (p = 0.001). Subjects with heterozygous GBA1 variants (carrier) had higher lyso-Gb1 levels, 5.8 (2.5-15.3) ng/mL, compared to wild-type GBA1, 4.9 (1.5-16), ng/mL (p = 0.001). Lyso-Gb1 levels, median (range), were 5 (2.7-10.7) in heterozygous GBA1 carriers with Parkinson's disease (PD), similar to lyso-Gb1 levels in subjects without PD. We call for a paradigm change for the diagnosis of GD based on lyso-Gb1 measurements and confirmatory GBA1 mutation analyses in DBS. Lyso-Gb1 levels could not be used to differentiate between heterozygous GBA1 carriers and wild type.

Impact of Long-Term Enzyme Replacement Therapy on Glucosylsphingosine (Lyso-Gb1) Values in Patients with Type 1 Gaucher Disease: Statistical Models for Comparing Three Enzymatic Formulations.

For three decades, enzyme replacement therapy (ERT), and more recently, substrate reduction therapy, have been the standard-of-care for type I Gaucher disease (GD1). Since 2012, three different ERTs have been available. No clinical trial or academic study has ever compared these ERTs beyond one year. Herein we compare the impact of the ERTs on repeated measurements of glucosylsphingosine (lyso-Gb1; the most sensitive and GD-specific biomarker). A total of 135 adult patients (77 (57%) female) with GD1, followed from July 2014 to March 2020 and treated with a single ERT (imiglucerase (n = 41, 30.4%), taliglucerase alfa (n = 21, 15.6%) and velaglucerase alfa (n = 73, 54.1%)), were included. Disease severity was defined by genotypes (mild: N370S (c.1226A>G) homozygous and N370S/R496H (c.1604G) compound heterozygous; severe: all other genotypes) and by the severity score index (SSI; mild: <7; severe: ≥7). Lyso-Gb1 testing was performed at Centogene™ on dry blood spot samples collected during routine visits. Patients treated with imiglucerase had higher lyso-Gb1 levels at different time points. A huge variation in lyso-Gb1 levels was noticeable both inter-individually and intra-individually for all three ERTs. A steeper and faster decrease of lyso-Gb1 levels was shown in velaglucerase alfa. Nevertheless, the differences between medications were not very large, and bigger numbers and more pretreatment data are required for more powerful conclusions.

Elevated holo-transcobalamin in Gaucher disease type II: A case report.

Gaucher disease (GD), one of the most common lysosomal disorders, is caused by deficiency of ß-glucocerebrosidase. Based on the presence and severity of neurological complications, GD is classified into types I, II (the most severe form), and III. Abnormalities in systemic markers of vitamin B12 (B12 ) metabolism have been reported in GD type I patients, suggesting a higher prevalence of B12 deficiency in these patients. A 2-month-old male with GD type II was admitted to the hospital presenting jaundice, hepatosplenomegaly, and ichthyosis. At admission, cholestasis and ascites, abnormal liver function enzymes, prolonged prothrombin time, and high levels of B12 were confirmed. Analysis of biomarkers of B12 status revealed elevated B12 and holo-transcobalamin (holo-TC) levels. The B12 profile found in our patient is the opposite to what is described for GD type I patients. Holo-TC may increase in inflammatory states or due to liver diseases. In GD, the accumulation of glucocerebroside may be a trigger that initiates a systemic inflammatory reaction, characterized by macrophage activation. We suggest higher levels of holo-TC could be associated with a more severe (neuronopathic) GD, and be a biomarker of GD type II.

Detection of glucosylsphingosine in dried blood spots for diagnosis of Gaucher disease by LC-MS/MS.

INTRODUCTION: Gaucher disease (GD) is caused by a deficiency of ß-glucosidase (GCase), leading to accumulation of glucosylceramide (GlcC) and glucosylsphingosine (Lyso-Gb1). Lyso-Gb1 is a reliable biomarker for GD. OBJECTIVES: This study aims to develop a simple, effective and accurate method for the screening and diagnosis of GD using dried blood spot (DBS) samples. METHODS: Lyso-Gb1 in DBS was extracted by 50% acetonitrile aqueous solution containing isotope-labeled internal standard and analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). A reference interval was established by analyzing samples from 277 healthy controls. Lyso-Gb1 was detected in the residual DBS samples from 142 high-risk patients with splenomegaly and/or thrombocytopenia. Based on GCase activity in DBS, samples were classified into four groups: confirmed GD patients (n = 52), GD carriers (n = 5), false positive (n = 36) and negative (n = 49). RESULTS: The optimized Lyso-Gb1 assay showed intra- and inter-assay variations ranged between 2.0%-8.2% and 3.8%-10.2%, respectively. Accuracies ranged from 93.5% to 112.6%. The lowest limit of quantification was 1 ng/mL. The normal reference interval of Lyso-Gb1 in DBS ranged from 2.1 to 9.9 ng/mL. Among the 142 subjects, except for one GD patient (Lyso-Gb1 > 2500 ng/mL), the Lyso-Gb1 concentrations in 51 GD patients ranged from 190.5 to 2380.6 ng/mL (the median 614.8 ng/mL). Also, one negative patient was found to have an elevated Lyso-Gb1 level (684.5 ng/mL), while the other patients were normal. The negative case was then confirmed to be an atypical GD patient with a c.1091A > G (p.Y364C) homozygous variant in PSAP gene by next generation sequencing. CONCLUSIONS: The optimized method to determine Lyso-Gb1 in DBS was demonstrated as a useful tool for the screening and diagnosis of GD.

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.

Value of Glucosylsphingosine (Lyso-Gb1) as a Biomarker in Gaucher Disease: A Systematic Literature Review.

The challenges in the diagnosis, prognosis, and monitoring of Gaucher disease (GD), an autosomal recessive inborn error of glycosphingolipid metabolism, can negatively impact clinical outcomes. This systematic literature review evaluated the value of glucosylsphingosine (lyso-Gb1), as the most reliable biomarker currently available for the diagnosis, prognosis, and disease/treatment monitoring of patients with GD. Literature searches were conducted using MEDLINE, Embase, PubMed, ScienceOpen, Science.gov, Biological Abstracts, and Sci-Hub to identify original research articles relevant to lyso-Gb1 and GD published before March 2019. Seventy-four articles met the inclusion criteria, encompassing 56 related to pathology and 21 related to clinical biomarkers. Evidence for lyso-Gb1 as a pathogenic mediator of GD was unequivocal, although its precise role requires further elucidation. Lyso-Gb1 was deemed a statistically reliable diagnostic and pharmacodynamic biomarker in GD. Evidence supports lyso-Gb1 as a disease-monitoring biomarker for GD, and some evidence supports lyso-Gb1 as a prognostic biomarker, but further study is required. Lyso-Gb1 meets the criteria for a biomarker as it is easily accessible and reliably quantifiable in plasma and dried blood spots, enables the elucidation of GD molecular pathogenesis, is diagnostically valuable, and reflects therapeutic responses. Evidentiary standards appropriate for verifying inter-laboratory lyso-Gb1 concentrations in plasma and in other anatomical sites are needed.

Altered level of plasma exosomes in patients with Gaucher disease.

Mutations in the glucocerebrosidase gene (GBA) cause Gaucher disease (GD), the lysosomal storage disorder (LSD), and are the most common genetic risk factor of Parkinson's disease (PD). Lysosome functionality plays a critical role for secretion of extracellular vesicles (EVs) and their content. Here we compared EVs from the blood plasma of 8 GD patients and 8 controls in terms of amounts, size distribution, and composition of their protein cargo. EVs were isolated via sequential centrifugation and characterized by сryo-electron microscopy (cryo-EM), nanoparticle tracking analysis (NTA), and dynamic light scattering (DLS). The presence of exosomal markers HSP70 and tetrasponins were analyzed by Western blot and flow cytometry. Protein profiling was performed by mass-spectrometry (shotgun analysis). Here, for the first time we reported an increased size and altered morphology in exosomes derived from blood plasma of GD patients. An increased size of plasma exosomes from GD patients compared to controls was demonstrated by cryo-EM and DLS (р<0.0001, p < 0.001, respectively) and confirmed by mode size detected by NTA (p < 0.02). Cryo-EM demonstrated an increased number of double and multilayer vesicles in plasma EVs from GD patients. We found that the EVs were enriched with the surface exosomal markers (CD9, СD63, CD81) and an exosome-associated protein HSP70 in case of the patients with the disease. Proteomic profiling of exosomal proteins did not reveal any proteins associated with PD pathogenesis. Thus, we showed that lysosomal dysfunction in GD patients lead to a striking alteration of plasma exosomes in size and morphology.

Effects of sphingolipids overload on red blood cell properties in Gaucher disease.

Gaucher disease (GD) is a genetic disease with mutations in the GBA gene that encodes glucocerebrosidase causing complications such as anaemia and bone disease. GD is characterized by accumulation of the sphingolipids (SL) glucosylceramide (GL1), glucosylsphingosine (Lyso-GL1), sphingosine (Sph) and sphingosine-1-phosphate (S1P). These SL are increased in the plasma of GD patients and the associated complications have been attributed to the accumulation of lipids in macrophages. Our recent findings indicated that red blood cells (RBCs) and erythroid progenitors may play an important role in GD pathophysiology. RBCs abnormalities and dyserythropoiesis have been observed in GD patients. Moreover, we showed higher SL levels in the plasma and in RBCs from untreated GD patients compared with controls. In this study, we quantified SL in 16 untreated GD patients and 15 patients treated with enzyme replacement therapy. Our results showed that the treatment significantly decreases SL levels in the plasma and RBCs. The increased SL content in RBCs correlates with abnormal RBC properties and with markers of disease activity. Because RBCs lack glucocerebrosidase activity, we investigated how lipid overload could occur in these cells. Our results suggested that SL overload in RBCs occurs both during erythropoiesis and during its circulation in the plasma.

Treatment Efficiency in Gaucher Patients Can Reliably Be Monitored by Quantification of Lyso-Gb1 Concentrations in Dried Blood Spots.

Gaucher disease (GD) is a lysosomal storage disorder that responds well to enzyme replacement therapy (ERT). Certain laboratory parameters, including blood concentration of glucosylsphingosine (Lyso-Gb1), the lyso-derivate of the common glycolipid glucocerebroside, correlate with clinical improvement and are therefore considered candidate-monitoring biomarkers. Whether they can indicate a reduction or loss of treatment efficiency, however, has not been systematically addressed for obvious reasons. We established and validated measurement of Lyso-Gb1 from dried blood spots (DBSs) by mass spectrometry. We then characterized the assay's longitudinal performance in 19 stably ERT-treated GD patients by dense monitoring over a 3-year period. The observed level of fluctuation was accounted for in the subsequent development of a unifying data normalization concept. The resulting approach was eventually applied to data from Lyso-Gb1 measurements after an involuntary treatment break for all 19 patients. It enabled separation of the "under treatment" versus "not under treatment" conditions with high sensitivity and specificity. We conclude that Lyso-Gb1 determination from DBSs indicates treatment issues already at an early stage before clinical consequences arise. In addition to its previously shown diagnostic utility, Lyso-Gb1 thereby qualifies as a monitoring biomarker in GD patients.

Real-world effectiveness of eliglustat in treatment-naïve and switch patients enrolled in the International Collaborative Gaucher Group Gaucher Registry.

Eliglustat is a first-line oral therapy for adults with Gaucher disease type 1 (GD1) with extensive, intermediate, or poor CYP2D6-metabolizer phenotypes (90% of patients). We report real-world outcomes after 2 years of eliglustat therapy in the International Collaborative Gaucher Group Gaucher Registry (NCT00358943). As of January 2019, baseline and 2-year data (±1 year) were available for 231 eliglustat-treated GD1 patients: 19 treatment-naïve (zero splenectomized) and 212 ERT patients who switched to eliglustat (36 splenectomized). Most patients (89%) were from the United States, where eliglustat was first approved. In treatment-naïve patients, mean hemoglobin increased from 12.4 to 13.4 g/dL (P = .004, n = 18), mean platelet count increased from 113 to 156 × 109 /L (P < .001, n = 17); mean spleen volume decreased from 7.4 to 3.5 multiples of normal (MN) (P = .02, n = 7); mean liver volume remained normal (n = 7), and median spine Z-score was unchanged (-1.3 to -1.2, n = 6). In non-splenectomized switch patients, mean hemoglobin remained stable/non-anemic (n = 167); mean platelet count remained stable/normal (n = 165); mean spleen volume decreased from 3.3 to 2.8 MN (P < .001, n = 64); mean liver volume remained normal (n = 63), and median lumbar spine Z-score improved from -0.7 to -0.4 (P = .014, n = 68). In splenectomized switch patients, mean hemoglobin remained stable/non-anemic (n = 31); mean platelet count increased from 297 to 324 × 109 /L (non-significant, n = 29); mean liver volume remained normal (n = 13); median spine Z-score improved from -0.8 to -0.6 (non-significant, n = 11). Median chitotriosidase decreased in all groups (P < .01 for all). These real-world results are consistent with eliglustat clinical trial results demonstrating long-term benefit in treatment-naïve patients and stability in ERT switch patients.

Open-label, expanded access study of taliglucerase alfa in patients with Gaucher disease requiring enzyme replacement therapy.

A multicenter, open-label, expanded-access study followed the safety of taliglucerase alfa, a plant cell-expressed recombinant enzyme replacement therapy (ERT), in adults with Gaucher disease previously treated with imiglucerase. Patients received taliglucerase alfa every 2 weeks for 9 months at a dose equivalent to their previous imiglucerase dose (Part A); patients were offered treatment for up to 33 months (Part B), and a later amendment allowed treatment-naïve patients. Fifty-eight patients received taliglucerase alfa (55.2% male; mean age, 46.1 years; mean bi-weekly dose, 35.2 U/kg; mean duration, 17.8 months); 51 patients previously received ERT, seven were treatment-naïve, and 36 completed the study. Most adverse events were mild or moderate; treatment-related adverse events were mild and transient. In previously treated patients, increases from baseline to last follow-up were observed for mean ± SE hemoglobin concentration (13.0 ± 0.3 g/dL to 13.4 ± 0.2 g/dL) and platelet count (179,242 ± 15,344/mm3 to 215,242 ± 17,867/mm3). Findings were similar in treatment-naïve patients (mean ± SE hemoglobin concentration and platelet count, 12.8 ± 0.3 g/dL to 13.5 ± 0.2 g/dL and 168,821 ± 14,368/mm3 to 204,641 ± 16,071/mm3, respectively). Taliglucerase alfa was well-tolerated for up to 33 months and demonstrated a durable therapeutic effect.

Immunoglobulin Abnormalities in Gaucher Disease: an Analysis of 278 Patients Included in the French Gaucher Disease Registry.

Gaucher disease (GD) is a rare lysosomal autosomal-recessive disorder due to deficiency of glucocerebrosidase; polyclonal gammopathy (PG) and/or monoclonal gammopathy (MG) can occur in this disease. We aimed to describe these immunoglobulin abnormalities in a large cohort of GD patients and to study the risk factors, clinical significance, and evolution. Data for patients enrolled in the French GD Registry were studied retrospectively. The risk factors of PG and/or MG developing and their association with clinical bone events and severe thrombocytopenia, two markers of GD severity, were assessed with multivariable Cox models and the effect of GD treatment on gammaglobulin levels with linear/logarithmic mixed models. Regression of MG and the occurrence of hematological malignancies were described. The 278 patients included (132 males, 47.5%) were followed up during a mean (SD) of 19 (14) years after GD diagnosis. PG occurred in 112/235 (47.7%) patients at GD diagnosis or during follow-up and MG in 59/187 (31.6%). Multivariable analysis retained age at GD diagnosis as the only independent risk factor for MG (> 30 vs. ≤30 years, HR 4.71, 95%CI [2.40-9.27]; p < 0.001). Risk of bone events or severe thrombocytopenia was not significantly associated with PG or MG. During follow-up, non-Hodgkin lymphoma developed in five patients and multiple myeloma in one. MG was observed in almost one third of patients with GD. Immunoglobulin abnormalities were not associated with the disease severity. However, prolonged surveillance of patients with GD is needed because hematologic malignancies may occur.