Plasma Chitotriosidase Activity Research Articles

Chitotriosidase activity and dynamics of computed tomography data in COVID-19 patients

Aim: To assess the relationship between initial plasma chitotriosidase (CHIT) activity and the dynamics of computed tomography (CT) data: lung injury volume, liver and spleen density in COVID-19 hospitalized patients.Material and Methods. The sub-analysis of the study registered in the Clinical Trial Registry with number: NCT04752085 was performed. The data of patients with available CT data of the chest on admission and at least once in dynamics during the period of hospitalization and the initial level of CTS in the blood plasma were analyzed. The density of the liver and spleen was determined in the scanned upper abdominal images, followed by the calculation of the ratio of the density of the liver to the density of the spleen.Results. A total of 121 patients were enrolled in this sub-analysis. Their baseline characteristics were as follows: median age 62 [53;70], males 48,7%. Between the day of admission and 7 [6;9] days of hospitalization, there was a significant increase in mean liver density from 52,04 [45,4; 56,7] to 57,5 [49,8; 62,7] HU and L/S ratio (liver to spleen ratio) 1,05 [0,91; 1,14] to 1,13 [0,99; 1,28], p < 0,001. The dynamics of the volume of lung tissue damage was multidirectional and, in general, did not change significantly. CHIT activity among patients whose lung injury volume increased during the hospitalization was significantly lower (65 [27; 119] nmol/ml/h) compared with patients whose lung injury volume did not change or decreased (124 [53; 232] nmol/ml/h), p = 0.006. The risk of lung injury progression was higher in patients with baseline CHIT level less than 100 nmol/h/ mL, (HR 3.1, 95% CI 1.4–6.9).Conclusion. Insufficient increase of CHIT activity can be associated with progression of lung injury, but does not affect the evolution of liver and spleen density as measured by CT.

A 20-Year Longitudinal Study of Plasma Chitotriosidase Activity in Treated Gaucher Disease Type 1 and 3 Patients-A Qualitative and Quantitative Approach.

Chitotriosidase is an enzyme produced and secreted in large amounts by activated macrophages, especially macrophages loaded with phagocytozed glycosphingolipid in Gaucher disease. Macrophages phagocytose decayed blood cells that contain a lot of sphingolipid-rich cell membranes. In Gaucher disease, due to a deficit in beta-glucocerebrosidase activity, the phagocytozed substrate glucocerebroside cannot undergo further catabolism. In such a situation, macrophages secrete chitotriosidase in proportion to the degree of overload. Gaucher disease (GD) is a recessively inherited disorder resulting in storage of glucosylceramide (GlcCer) in lysosomes of tissue macrophages. It is directly caused by the deficiency of beta-glucocerebrosidase (GBA) activity. Chitotriosidase has been measured systematically each year in the same group of 49 patients with type 1 and 3 GD for over 20 years. Our analysis showed that chitotriosidase is very sensitive biomarker to enzyme replacement therapy (ERT). The response to treatment introduction is of an almost immediate nature, lowering pathologically high chitotriosidase levels by a factor of 2 in a time scale of 8 months, on average. Long term enzyme replacement therapy (ERT) brings chitotriosidase activity close to reference values. Finally, reducing the dose of ERT quickly boosts chitotriosidase activity, but restoring the initial dose of treatment brings chitotriosidase level of activity back onto the decreasing time trajectory.

Safety and efficacy of eliglustat combined to enzyme replacement therapy for lymphadenopathy in patients with Gaucher disease type 3

Patients with Gaucher disease type 3 (GD3), especially those with GBA p.L444P homozygous mutation, often suffer from complications including lymphadenopathy even under regular enzyme replacement therapy (ERT). In order to improve their outcome, we administrated eliglustat, a substrate reduction therapy (SRT), in combination with ERT to four patients, age ranged 9–18 years, for two years. The results revealed that patients' plasma glucosylsphingosine (lyso-GL1) level and chitotriosidase activity both decreased after adding eliglustat. In three patients who completed follow-up MRI scanning, sizes of lymph nodes all decreased. No severe adverse events were attributed to eliglustat. Therefore, our data suggest that a combined SRT and ERT treatment may improve the ERT-resistant symptoms in patients with GD3.

Increased Plasma YKL-40 Level and Chitotriosidase Activity in Cystic Fibrosis Patients.

We investigated plasma YKL-40 levels and chitotriosidase (CHIT1) activity in patients with cystic fibrosis (CF) lung disease and evaluated clinically relevant factors that may affect their levels. Plasma samples were obtained from pediatric (n = 19) and adult patients (n = 15) during exacerbation, discharge, and stable period of the disease. YKL-40 levels and chitotriosidase activity were measured by enzyme-linked immunosorbent assay and fluorometric assay, respectively. Data were compared with healthy children and adults of similar age. YKL-40 levels of pediatric and adult CF patients at all periods were significantly higher than controls (p < 0.001 and p < 0.05). CHIT1 activities of adult patients at all periods were significantly higher compared to controls (p < 0.05). On the other hand, CHIT1 activities of pediatric CF patients were similar with controls. YKL-40 levels of exacerbation period of adult CF patients were negatively correlated with forced vital capacity (FVC) (r = - 0.800, p = 0.014) and forced expiratory volume in 1s (FEV1) (r = - 0.735, p = 0.008). YKL-40 levels in the exacerbation period of pediatric CF patients were negatively correlated with FVC (r = - 0.697, p = 0.0082) and FEV1 (r = - 0.720, p = 0.006). CHIT1 activity may be a valuable marker of chronic inflammation in adult CF patients who suffer from CF for a longer period compared to pediatric patients. Increased YKL-40 levels in both pediatric and adult patients compared to controls may point to a role in between CF pathology.

Serum Chitotriosidase level as a Novel Biomarker for Therapeutic Monitoring of Nephropathic Cystinosis among the Iraqi children

Background: Cystinosis is a rare autosomal recessive lysosomal storage disease with high morbidity and mortality. It is caused by mutations in the CTNS gene that encodes the cystine transporter, cystinosin, which leads to lysosomal cystine accumulation. It is the major cause of inherited Fanconi syndrome, and should be suspected in young children with failure to thrive and signs of renal proximal tubular damage. The diagnosis can be missed in infants, because not all signs of renal Fanconi syndrome are present during the first months of life. Elevated white blood cell cystine content is the cornerstone of the diagnosis. Since chitotriosidase (CHIT1 or chitinase-1) is mainly produced by activated macrophages both in normal and inflammatory conditions which suggest that cystinosis should be included within the differential diagnosis of disorders associated with increased plasma chitotriosidase activity. This study is aimed to estimate serum chitotriosidase level, as a screening marker and therapeutic monitor for cystinosis disease in Iraqi children with cystinosis.Subjects and Methods: The present study is a case-control study that included samples of 30 children with nephropathic cystinosis, compared to 25 healthy control children from those attending at The Genetic Rare Diseases Center / AL-Emamain AL-Kadhimain Teaching Hospital, Baghdad-Iraq.Results: Our results reported that cystinotic children had a marked elevation of serum chitotriosidase activity, compared to age-matched healthy children, besides a significant associated with leukocyte-cystine content for cystinotic patients.CHT1 as a Novel BiomarkerConclusion: Estimation of serum chitotriosidase activity might aid in monitoring the therapeutic benefits of cysteamine therapy, as well as the prognosis of the disease when WBC cystine assessment is not available.Key Words: Cystinosis, Cysteamine, Chitotriosidase.

Impact of Age at Starting Cysteamine Therapy on Serum Chitotriosidase in Cystinotic Iraqi Children

Cystinosis is a rare autosomal recessive lysosomal storage disease with high morbidity and mortality. Itis caused by mutations in the CTNS gene that encodes the cystine transporter, cystinosin, which leadsto lysosomal cystine accumulation. It is the major cause of inherited Fanconi syndrome and should besuspected in young children with failure to thrive and signs of renal proximal tubular damage. The diagnosiscan be missed in infants, because not all signs of renal Fanconi syndrome are present during the first monthsof life. Elevated white blood cell cystine content is the corner stone for the diagnosis. Since chitotriosidase(CHIT1 or chitinase-1) is mainly produced by activated macrophages both in normal and inflammatoryconditions. Which suggests that cystinosis should be included in the differential diagnosis of disorders withincreased plasma chitotriosidase activity. This study is aimed to investigate the impact of cystinosis on therenal function in relation to age at detection and initiation of treatment course,besides estimating serumchitotriosidase level,as a screening marker and therapeutic monitor for cystinosis disease in Iraqi childrenwith cystinosis.The present study is a case-control study included a samples of 30 children with nephropathic cystinosis,compared to 25 healthy control children from those attending at The Genetic Rare Diseases Center/ALEmamain AL-Kadhimain teaching hospital, Baghdad-Iraq.Our results report patients who started taking the medication (cysteamine) before two years of age werepresented with significantly lower levels of cystine and chitotriosidase in addition to better renal function(higher GFR) (P-value = 0.0001) .In other words, earlier treatment led to better disease control and lessdeterioration of renal function.In conclusion serum chitotriosidase activity estimation might aid in monitoring therapeutic benefit ofcysteamine therapy and the prognosis of the disease when WBC cystine assessment is not available.

Volume of Gadolinium Enhancement and Successful Repair of the Blood-Brain Barrier in Cerebral Adrenoleukodystrophy.

Up to 40% of boys with adrenoleukodystrophy develop a severe central nervous system demyelinating form (cALD) characterized by white matter changes and gadolinium enhancement on magnetic resonance imaging (MRI). Hematopoietic cell transplant (HCT) is the only proven means to attenuate cALD progression. The elimination of active neuroinflammation is indicated radiographically by the resolution of gadolinium (Gd) enhancement and correlates to speed of donor neutrophil recovery. We analyzed 66 boys with cALD undergoing HCT for biomarkers correlating with early (30 days post-HCT) Gd signal resolution. We found that log Gd volume (cm3) on pre-HCT MRI strongly positively correlated to day 30 Gd resolution (P = .0003) with smaller volume correlating to higher proportion resolved, as was the baseline gadolinium intensity score (P = .04), plasma chitotriosidase activity (P = .04), and faster absolute neutrophil count recovery (P = .03). In multivariate analysis, log Gd volume remained superior in determining which patients would have Gd signal resolution by 30 days post-HCT (P = .016). A final analysis indicated that early Gd resolution also correlated with less neurologic progression from baseline to 1 year following HCT (P = .006). MRI Gd volume may serve as a contributing biomarker to better delineate outcomes and an important metric in comparing therapies in the treatment of cALD.

Chitotriosidase Activity in Plasma and COPD Exacerbations.

This study aimed to determine the association between plasma chitotriosidase activity and the clinical characteristics and exacerbation rate of COPD patients. The study comprised 97 patients with COPD. Their clinical characteristics and a history of exacerbations in the last 12months were noted. Plasma chitotriosidase activity was determined. Patients were followed up for 12months, and the number of moderate and severe exacerbations during this period was recorded. Chitotriosidase activity positively correlated with patient age (rho = 0.217, p = 0.036) and inversely with CAT (rho = - 0.240, p = 0.020). There was no correlation with lung function. Chitotriosidase activity was significantly lower in patients with a history of ≥ 2 exacerbations compared to patients without a history of exacerbations (93 [38-312] vs. 264 [168-408] nmol/h/mL, p = 0.033). Overall, there was no difference in chitotriosidase activity between patients with or without observed exacerbations. Patients with a history of ≥ 1 exacerbation and ≥ 1 observed exacerbation had higher chitotriosidase activity compared to patients without further exacerbations (240 [144-456] vs. 52 [39-240] nmol/h/mL, p = 0.035). Multivariate analysis identified FEV1 (HR 0.976, 95% CI 0.956-0.996, p = 0.016) and blood eosinophil percentage (HR 1.222, 95% CI 1.048-1.424, p = 0.011) as independent predictors of future exacerbations in the total patient population, while in patients with a history of ≥ 1 exacerbation ,the only independent predictor was chitotriosidase activity (HR per 10nmol/h/mL 1.028, 95% CI 1.002-1.055, p = 0.037). While mixed associations between chitotriosidase activity and clinical outcomes were seen, chitotriosidase activity could be a predictor of future exacerbations in patients with a history of ≥ 1 exacerbation in the past 12months.

MRI Gadolinium Volume in Cerebral Adrenoleukodystrophy: A Novel Biomarker to Quantify Cerebral Inflammation and Predict Transplant Response.

Adrenoleukodystrophy (ALD) is caused by mutations within the X-linked <i>ABCD1</i> gene resulting in the inability to transport acylated very long chain fatty acids (VLCFA) into the peroxisome for degradation. VLCFA subsequently accumulate in tissues, including the central nervous system. Up to 40% of boys develop a severe, progressive demyelinating form of ALD, cerebral ALD (cALD), resulting in regions of demyelination observed on brain magnetic resonance imaging (MRI) that are associated with a "garland ring" of gadolinium contrast enhancement. Gadolinium enhancement indicates blood-brain-barrier (BBB) disruption and an active inflammatory disease process. Only hematopoietic cell transplant (HCT) is accepted as therapy sufficient to halt neurologic progression and resolve the observed gadolinium enhancement, although the mechanism of disease arrest is unknown. We have previously shown that rapid donor neutrophil recovery after HCT facilitates MRI gadolinium resolution. We now show early (28 days post HCT) gadolinium resolution correlates well with improved neurologic outcomes measured 1-year post HCT. We recently developed a method to quantify gadolinium on imaging and calculate a gadolinium (Gad) volume given in cubic centimeters (cc). We evaluated Gad volume and other previously described imaging and transplant related biomarkers in 66 boys who underwent HCT. In univariate analysis we found day 28 gadolinium resolution was associated with the following pre-transplant parameters: less Gad volume (7.3 cc versus 2.7 cc, p=0.01), less Gad intensity (p=0.04) and less extensive demyelination as determined by the Loes MRI scoring system (p=0.03). In addition, resolution of Gad enhancement by day 28 was associated with lower pre-HCT plasma and cerebral spinal fluid chitotriosidase activity (p=0.04 for both), and faster neutrophil recovery post HCT (less than 16 days versus greater than 16 days, p=0.03). Multivariate analysis revealed that only less Gad volume was predictive of rapid gadolinium resolution at 28 days post HCT (p = 0.02). This is the first data to quantify the extent of cerebral inflammation in cALD as defined by Gad positivity and its resolution after HCT. Future studies should consider use of Gad volume prior to HCT as a useful biomarker for time to resolution.

Evaluation of two approaches to lysosomal acid lipase deficiency patient identification: An observational retrospective study

Background and aimsLysosomal acid lipase deficiency (LALD) leads to the accumulation of cholesteryl esters and/or triglycerides (TG) in lysosomes due to the lack of the enzyme codified by the LIPA gene. The most common symptoms are dyslipidaemia and hypertransaminasemia, together with manifestations common to other lysosomal storage disorders (LSDs), including visceromegalies and elevated plasma biomarkers. Alteration of the lipid-liver profile (LLP) has been widely applied as a criterion for LALD screening, but the usefulness of biomarkers has not yet been explored. Our purpose was to explore the utility of plasma chitotriosidase activity (ChT) and CCL18/PARC concentration in addition to LLP to identify LALD patients in an observational retrospective study of two different sample collections. MethodsBiological samples refining: Collection 1 (primary hypercholesterolemia suspected) included unrelated individuals with hyperlipidaemia and without LDLR, APOB and PCSK9 gene mutations (Set 1), and Collection 2 (LSD suspected) included individuals without definitive LSD diagnosis (Set 2). We assessed plasma LLP (total cholesterol and its fractions, TG concentration and transaminases activities), as well as plasma ChT and CCL18/PARC. All subjects with anomalous LLP and/or biomarker levels were LIPA sequenced. ResultsTwenty-four subjects showed altered LLP and/or biomarkers. We identified two LALD patients (one homozygous and one compound heterozygous) and one carrier of a novel LIPA variant. ConclusionsThe measurement of plasma ChT and CCL18/PARC combined with LLP will be a useful approach to identifying LALD patients in retrospective LALD patient studies.

Biochemical and molecular characterization of adult patients with type I Gaucher disease and carrier frequency analysis of Leu444Pro - a common Gaucher disease mutation in India

BackgroundGaucher disease is a rare pan-ethnic disorder which occurs due to an increased accumulation of undegraded glycolipid glucocerebroside inside the cells’ lysosomes. A beta-Glucosidase (GBA) gene defect results in glucocerebrosidase enzyme deficiency. Though the disease is mainly diagnosed in childhood, the adult manifestation is often missed or identified late due to the failure to recognize the heterogeneous clinical presentation. The present study includes seven unrelated Indian adult patients (age range: 20–40 years) having splenomegaly, with or without hepatomegaly, cytopenia and bone abnormality.MethodsThe biochemical investigation implicated measuring plasma chitotriosidase enzyme activity followed by confirmatory test of β-Glucosidase enzyme activity from the leukocytes. The molecular characterization involved patients’ initial screening for the common Gaucher mutation (Leu444Pro). Later, all patients were subjected to whole GBA gene coding region study using bidirectional Sanger sequencing. The population screening for common Gaucher disease mutation (Leu444Pro) was executed in 1200 unrelated and healthy Indian subjects by Restriction Fragment Length Polymorphism-Polymerase Chain Reaction technique. The allele frequency was calculated using Hardy-Weinberg formula.ResultsThe biochemical analysis revealed a significant reduction in the β-Glucosidase activity in all the patients. Also, an elevated level of plasma Chitotriosidase activity in five patients supported their diagnosis of Gaucher disease. Sanger sequencing established four patients with homozygous variation and three patients with compound heterozygous variation in GBA gene. This study uncovers two missense variants (Ala448Thr and Val17Gly) not previously reported in Gaucher disease patients. Also the known mutations like Leu444Pro, Arg329Cys, Asp315Asn, Ser125Arg, and Arg395Cys were identified in these patients. The homology modeling suggested the destabilization of the protein structure due to novel variants. The Leu444Pro mutation screening in the Indian population spotted two people as a carrier. This emerged the carrier frequency of 1:600 along with wild-type allele frequency 0.97113 and mutant allele frequency 0.02887.ConclusionsThe study reports novel and known variants identified in the GBA gene in seven adult patients. The given study is the first report on the carrier frequency of the Leu444Pro mutant allele in an Indian population which will help understanding the burden and susceptibility of Gaucher disease to affect next generation in India.

WS16.4 Plasma YKL-40 levels and chitotriosidase activity in cystic fibrosis patients

WS16.4 Plasma YKL-40 levels and chitotriosidase activity in cystic fibrosis patients

WITHDRAWN: Plasma Chitotriosidase Activity and Arteriogenic Erectile Dysfunction: Association with the Presence, Severity, and Duration

Introduction. Plasma chitotriosidase (ChT) activity is associated with the presence of atherosclerosis and is a new cardiovascular risk marker. Although available evidence supports its role in atherogenesis, there is a lack of an obvious correlation between plasma ChT activity and erectile dysfunction (ED). Aim. Our aim was to investigate the association of the level of serum ChT activity with ED. Main Outcome Measures. Erectile function was assessed using Sexual Health Inventory for Men (SHIM). Serum fasting lipid profile (plasma total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol, and triglycerides); sex hormones (luteinizing hormone, follicle-stimulating hormone, prolactin, total testosterone, and estradiol); and thyroid-stimulating hormone were measured. Plasma ChT activity, as well as K(m), V(max), optimum pH, and heat stability of the ChT were also assessed. Penile duplex ultrasound examination before and after intracavernous injection of 20 microg prostaglandin E1 (PGE(1)), pudendal nerve conduction tests and sensory-evoked potential studies were done to identify patients with arteriogenic ED. Intima-media thickness (IMT) and plaque formation of common carotid artery were determined bilaterally using B-mode ultrasonography. Methods. A total of 124 normolipidemic patients with ED and 120 healthy controls were recruited for this study. Results. Serum ChT activity in patients with ED (116 +/- 18 nmol/h/mL) was significantly higher than in normal control subjects (51 +/- 12 nmol/h/mL) (P < 0.001). There was a significant positive correlation between plasma ChT activity and (i) severity of ED and (ii) duration of ED (r = 0.68, P = 0.004; and r = 0.62, P = 0.01 respectively).We also found that all ChT kinetic parameters assessed (K(m), V(max), and optimum pH) in plasma of ED patients were significantly different from those of normal controls (all P < 0.001). The results of heat stability analysis, demonstrated that plasma ChT activity in the normal individuals was more stable than in the patients with arteriogenic ED (P < 0.001). A significant correlation was seen between the plasma ChT activity and the mean common carotid IMT (r = 0.78, P = 0.002). Moreover, a significant correlation was seen between the severity of ED and mean common carotid IMT (r = 0.74, P = 0.003). We did not address chitotriosidase genotype. Conclusions. Our results indicate that plasma ChT activity is increased in normolipidemic patients with arteriogenic ED, suggesting its possible role in the pathophysiology of arteriogenic ED. The clinical significance of this increase should be assessed in further studies. Safarinejad MR, and Safarinejad SH. Plasma chitotriosidase activity and arteriogenic erectile dysfunction: Association with the presence, severity, and duration. J Sex Med **;**:**-**.

Plasma chitotriosidase activity versus plasma glucosylsphingosine in wide spectrum of Gaucher disease phenotypes – A statistical insight

Deficiency of beta-glucocerebrosidase (GBA) leads to Gaucher disease (GD), an inherited disorder characterised by storage of glucosylceramide (GlcCer) in lysosomes of tissue macrophages. Macrophages activated by accumulated GlcCer secrete chitotriosidase. Plasma chitotriosidase activity is significantly elevated in patients with active GD and has been suggested to indicate total body Gaucher cell load.There are two biomarkers used to assess the severity of GD - chitotriosidase has been measured for over 20 years, and deacylated GlcCer, known as glucosylsphingosine (GlcSph) is thought to be even more adequate, as it is almost a direct storage substrate.In this paper we focused entirely on statistical analysis, performing a thorough search of possible relations, dependencies and differences in the levels of these two biomarkers in a cohort of 64 Polish GD patients. We found that the treatment of GD with enzyme replacement therapy (ERT) changes the distribution of the disease biomarkers; their levels follow a normal distribution only in untreated patients.The variable “disease biomarker level” was found dependent of the binary variable “treated with ERT or not”. It was found independent of the following variables: “disease type”, “splenectomized or not”, and “heterozygous for 24-bp duplication for CHIT1 variant” or “CHIT1 wild type”.An almost perfect linear correlation (coefficient of determination R2 = 0.99) between the chitotriosidase activity and GlcSph level was revealed in splenectomized patients.

WORLDSymposium™ 2018 Program.

Deficiency of beta-glucocerebrosidase (GBA) leads to Gaucher disease (GD), an inherited disorder characterised by storage of glucosylceramide (GlcCer) in lysosomes of tissue macrophages. Macrophages activated by accumulated GlcCer secrete chitotriosidase. Plasma chitotriosidase activity is significantly elevated in patients with active GD and has been suggested to indicate total body Gaucher cell load.There are two biomarkers used to assess the severity of GD - chitotriosidase has been measured for over 20 years, and deacylated GlcCer, known as glucosylsphingosine (GlcSph) is thought to be even more adequate, as it is almost a direct storage substrate.In this paper we focused entirely on statistical analysis, performing a thorough search of possible relations, dependencies and differences in the levels of these two biomarkers in a cohort of 64 Polish GD patients. We found that the treatment of GD with enzyme replacement therapy (ERT) changes the distribution of the disease biomarkers; their levels follow a normal distribution only in untreated patients.The variable “disease biomarker level” was found dependent of the binary variable “treated with ERT or not”. It was found independent of the following variables: “disease type”, “splenectomized or not”, and “heterozygous for 24-bp duplication for CHIT1 variant” or “CHIT1 wild type”.An almost perfect linear correlation (coefficient of determination R2 = 0.99) between the chitotriosidase activity and GlcSph level was revealed in splenectomized patients.

Plasma chitotriosidase activity versus CCL18 level for assessing type I Gaucher disease severity: protocol for a systematic review with meta-analysis of individual participant data

BackgroundGaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by deficiency in acid beta-glucosidase. GD exhibits a wide clinical spectrum of disease severity with an unpredictable natural course. Plasma chitotriosidase activity and CC chemokine ligand 18 (CCL18) have been exchangeably used for monitoring GD activity and response to enzyme replacement therapy in conjunction with clinical assessment. Yet, a large-scale head-to-head comparison of these two biomarkers is currently lacking. We propose a collaborative systematic review with meta-analysis of individual participant data (IPD) to compare the accuracy of plasma chitotriosidase activity and CCL18 in assessing type I (i.e., non-neuropathic) GD severity.MethodsEligible studies include cross-sectional, cohort, and randomized controlled studies recording both plasma chitotriosidase activity and CCL18 level at baseline and/or at follow-up in consecutive children or adult patients with type I GD. Pre-specified surrogate outcomes reflecting GD activity include liver and spleen volume, hemoglobin concentration, platelet count, and symptomatic bone events with imaging confirmation. Primary studies will be identified by searching Medline (1995 onwards), EMBASE (1995 onwards), and Cochrane Central Register of Controlled Trials (CENTRAL). Electronic search will be complemented by contacting research groups in order to identify unpublished relevant studies. Where possible, IPD will be extracted from published articles. Corresponding authors will be invited to collaborate by supplying IPD. The methodological quality of retrieved studies will be appraised for each study outcome, using a checklist adapted from the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome will be a composite of liver volume >1.25 multiple of normal (MN), spleen volume >5 MN, hemoglobin concentration <11 g/dL, or platelet count <100 × 109/L. Effect size estimates for biomarker comparative accuracy in predicting outcomes will be reported as differences in areas under receiver operating characteristic curves along with 95% confidence intervals. Effect size estimates will be reported as (weighted) mean differences along with 95% confidence intervals for each biomarker according to outcomes. IPD meta-analysis will be conducted with both one- and two-stage approaches.DiscussionValid and precise accuracy estimates will be derived for CCL18 relative to plasma chitotriosidase activity in discriminating patients according to GD severity.Systematic review registrationPROSPERO 2015 CRD42015027243

A rare form of Gaucher disease resulting from saposin C deficiency

Gaucher disease is mainly caused by the deficiency of lysosomal acid β-glucosidase. Gaucher disease caused by the deficiency of saposin C is rare. Here we report a patient mainly presenting with hepatosplenomegaly, thrombocytopenia and anemia. EEG examination revealed increased theta waves. Gaucher cells identified in his bone marrow and the highly elevated plasma chitotriosidase activity and glucosylsphingosine supported a diagnosis of Gaucher disease. However, the leukocyte β-glucosidase activity was in a normal range. Sanger sequencing revealed a novel maternal exonic mutation c.1133C>G (p.Pro378Arg) in exon 10 of the PSAP gene, which codes the Sap C domain of PSAP protein. To search for other underlying mutations in this patient, whole genome sequencing was applied and revealed a deletion involving exon 2 to 7 of PSAP gene. The deletion appears as a de novo event on paternal chromosome. We concluded that biallelic mutations of PSAP gene were the cause of this patient's Gaucher disease. Our finding expands the mutation spectrum of Gaucher disease with saposin C deficiency.

Modelling long-term evolution of chitotriosidase in non-neuronopathic Gaucher disease

Chitotriosidase, an enzyme secreted by activated macrophages, is widely used as a biomarker for therapeutic monitoring and patient follow-up in Gaucher disease (GD), a lysosomal disorder caused by an inherited deficiency of glucocerebrosidase. We analyzed the long-term evolution of chitotriosidase aiming to establish an accurate model that describes the influence of enzyme replacement therapy (ERT) and the impact of several covariates. A total of 55 patients with non-neuronopathic (type 1) GD were followed for almost 17 years (during a maximum of 7.57 and 8.96 years, before and after the onset of ERT, respectively). Plasma chitotriosidase activity, measured yearly before the onset of ERT and at 6-month intervals after the initiation of ERT, was analyzed as a function of several covariates (age at diagnosis and at ERT initiation, nature of the most frequent genotypes, spleen status and the occurrence of bone complications). The evolution of chitotriosidase was approximated by a sigmoidal function, which allows the calculation of predicted values, based on several parameters inferred from our data. Splenectomy and the occurrence of bone complications significantly delayed the decline in chitotriosidase activity and induced higher mean residual values after long-term (4–9 years) ERT. Likewise, patients who started ERT infusions under 15 years of age had significantly higher mean residual chitotriosidase activities. The influence of other covariates did not reach statistical significance. In conclusion, we propose a novel model describing the evolution of chitotriosidase, allowing more accurate treatment adjustments, according to the variations of this biomarker.

Assessment of plasma chitotriosidase activity, CCL18/PARC concentration and NP-C suspicion index in the diagnosis of Niemann-Pick disease type C: a prospective observational study

BackgroundNiemann-Pick disease type C (NP-C) is a rare, autosomal recessive neurodegenerative disease caused by mutations in either the NPC1 or NPC2 genes. The diagnosis of NP-C remains challenging due to the non-specific, heterogeneous nature of signs/symptoms. This study assessed the utility of plasma chitotriosidase (ChT) and Chemokine (C–C motif) ligand 18 (CCL18)/pulmonary and activation-regulated chemokine (PARC) in conjunction with the NP-C suspicion index (NP-C SI) for guiding confirmatory laboratory testing in patients with suspected NP-C.MethodsIn a prospective observational cohort study, incorporating a retrospective determination of NP-C SI scores, two different diagnostic approaches were applied in two separate groups of unrelated patients from 51 Spanish medical centers (n = 118 in both groups). From Jan 2010 to Apr 2012 (Period 1), patients with ≥2 clinical signs/symptoms of NP-C were considered ‘suspected NP-C’ cases, and NPC1/NPC2 sequencing, plasma chitotriosidase (ChT), CCL18/PARC and sphingomyelinase levels were assessed. Based on findings in Period 1, plasma ChT and CCL18/PARC, and NP-C SI prediction scores were determined in a second group of patients between May 2012 and Apr 2014 (Period 2), and NPC1 and NPC2 were sequenced only in those with elevated ChT and/or elevated CCL18/PARC and/or NP-C SI ≥70. Filipin staining and 7-ketocholesterol (7-KC) measurements were performed in all patients with NP-C gene mutations, where possible.ResultsIn total across Periods 1 and 2, 10/236 (4%) patients had a confirmed diagnosis o NP-C based on gene sequencing (5/118 [4.2%] in each Period): all of these patients had two causal NPC1 mutations. Single mutant NPC1 alleles were detected in 8/236 (3%) patients, overall. Positive filipin staining results comprised three classical and five variant biochemical phenotypes. No NPC2 mutations were detected. All patients with NPC1 mutations had high ChT activity, high CCL18/PARC concentrations and/or NP-C SI scores ≥70. Plasma 7-KC was higher than control cut-off values in all patients with two NPC1 mutations, and in the majority of patients with single mutations. Family studies identified three further NP-C patients.ConclusionThis approach may be very useful for laboratories that do not have mass spectrometry facilities and therefore, they cannot use other NP-C biomarkers for diagnosis.

Twelve years of experience with miglustat in the treatment of type 1 Gaucher disease: The Spanish ZAGAL project

We report data from a prospective, observational study (ZAGAL) evaluating miglustat 100mg three times daily orally. in treatment-naïve patients and patients with type 1 Gaucher Disease (GD1) switched from previous enzyme replacement therapy (ERT). Clinical evolution, changes in organ size, blood counts, disease biomarkers, bone marrow infiltration (S-MRI), bone mineral density by broadband ultrasound densitometry (BMD), safety and tolerability annual reports were analysed. Between May 2004 and April 2016, 63 patients received miglustat therapy; 20 (32%) untreated and 43 (68%) switched. At the time of this report 39 patients (14 [36%] treatment-naïve; 25 [64%] switch) remain on miglustat. With over 12-year follow-up, hematologic counts, liver and spleen volumes remained stable. In total, 80% of patients achieved current GD1 therapeutic goals. Plasma chitotriosidase activity and CCL-18/PARC concentration showed a trend towards a slight increase. Reductions on S-MRI (p=0.042) with an increase in BMD (p<0.01) were registered. Gastrointestinal disturbances were reported in 25/63 (40%), causing miglustat suspension in 11/63 (17.5%) cases. Thirty-eight patients (60%) experienced a fine hand tremor and two a reversible peripheral neuropathy. Overall, miglustat was effective as a long-term therapy in mild to moderate naïve and ERT stabilized patients. No unexpected safety signals were identified during 12-years follow-up.