Deficient Glucocerebrosidase Activity Research Articles

Changing clinical manifestations of Gaucher disease in Taiwan

BackgroundGaucher disease (GD) is a lysosomal storage disorder characterized by deficient glucocerebrosidase activity that results from biallelic mutations in the GBA1 gene. Its phenotypic variability allows GD to be classified into 3 subtypes based on the presence and extent of neurological manifestations. Enzyme replacement therapy (ERT) has been available for all patients with GD in Taiwan since 1998. Newborn screening (NBS) for GD has been available since 2015. This study attempted to unveil the clinical features of patients diagnosed with GD during different eras in Taiwan.Materials and methodsData from the health records of two tertiary hospitals responsible for two-thirds of the patients with GD in Taiwan were used. The study population included all patients identified as having GD between 1998, and April 2022, in these two hospitals for review. A total of 42 individuals were included, six of whom were diagnosed by NBS.ResultsOur cohort presented a higher proportion of GD3 individuals, both by clinical suspicion and by NBS diagnosis, than that reported worldwide. The major subtypes that were recognized following NBS diagnosis were GD2 and GD3. The majority of GD patients carry at least one p.Leu483Pro variant. The 5-year survival rates were 0% for GD2 patients and 100% for patients with other subtypes. Patients diagnosed during the post-NBS era were free of symptoms on initial presentation, except for those with the GD2 subtype. For those diagnosed earlier, ERT was shown to be effective in terms of improved hemograms and prevented bone crises. However, the neurological symptoms in GD3 patients progressed despite ERT intervention.ConclusionERT is essential in reversing the hematological presentations and preventing the skeletal complications of GD. Timely diagnosis of GD with NBS allows for early intervention with ERT to prevent disease progression and complications. However, the need for effective intervention for neurological dysfunction remains unmet.

GBA1 variants in Brazilian Gaucher disease patients

Gaucher disease (GD) is an autosomal recessive lysosomal disorder caused by pathogenic variants in GBA1 which result in the deficient activity of glucocerebrosidase (GCase). There are few data on the genetic characterization of Brazilian GD patients. This study aimed at characterizing the genotype of 72 unrelated Brazilian GD patients (type I = 63, type II = 4, type III = 5; male = 31). Forty patients were from South Brazil (SB), and 32 were from other regions of Brazil (Others). The exons and exon/intron junctions of GBA1 were analyzed by Sanger sequencing in 8 patients, or by massive parallel sequencing followed by Sanger of exons 9 and 10 in 64 patients. In total, 31 pathogenic variants were identified. The most frequent allele found was N370S (p.(Asn409Ser)) (41.0%), and the most frequent genotype was N370S/RecNciI p.[Asn409Ser];[Leu483Pro;Ala495Pro;Val499=](23.6%). Three variants (N370S – in exon 9, and RecNciI and L444P (p.(Leu483Pro), in exon 10) correspond to 76.3% of total alleles in SB and 59.4% in Others. Two novel variants were described: c.326del(p.(Gln109Argfs*9)) and c.690G>A (p.(?)). Although sequencing all the exons of GBA1 is the gold-standard method for the genetic analysis of GD patients, a step analysis can be proposed for Brazilian patients, starting with analysis of exons 9 and 10. The N370S allele is the most frequently associated with GD in Brazil.

Bone Marrow Plasma Cell Burden in Gaucher Disease Correlates with Local Macrophage Infiltration and May be Altered By Disease Treatment

Introduction Gaucher disease (GD), caused by deficient activity of lysosomal glucocerebrosidase, results in tissue infiltration by transformed macrophages (Gaucher cells, GC), loaded with undigested glycolipids. Ensuing clinical signs and symptoms include skeletal lesions and cytopenias, and seem to be due to both local tissue replacement by pathological infiltrates but also to accompanying inflammatory response, elicited by engorged macrophages. Bone marrow GC infiltration coincides with increased microvascular density and skewed angiogenic profiles. The basis for increased risk of plasma cell (PC) dyscrasia in GD remains however still unexplained. The presented study aimed to investigate patterns of PC distribution in bone marrow of untreated GD patients, potential their clinical correlates and evolution during treatment. Methods Study material includes BM samples from 11 previously untreated GD1 patients (7 males, 4 females), followed at the Hematology Center, Karolinska University Hospital, Stockholm, Sweden. Diagnosis of GD was previously confirmed with proven deficient glucocerebrosidase activity in PB, and demonstrated GBA1 mutation. The study was performed in accordance with Declaration of Helsinki, and institutional ethical permit was obtained. Clinical data were retrieved from patient journals. After BM sampling, 10 patients began disease specific therapy, with 9 subjects receiving enzyme replacement therapy (ERT), and one treated with substrate reduction therapy (SRT). Bone marrow samples (trephine biopsies or fine needle aspirates) were taken as part of routine hematologic work-up, at baseline and, if needed, during follow-up. Samples were routinely processed at the Department of Clinical Pathology and Cytology at the same hospital. Plasma cell burden and distribution were studied in immunohistochemically stained sections (CD138), scanned at 40x magnification using the NanoZoomer S360 Digital slide scanner (Hamamatsu Photonics, Hamamatsu, Japan). NDPI.view2 Viewing software was used for scan evaluation, and image saving (JPEG format, 461 nm/pix resolution). For each sample, 5 fields with prominent Gaucher cell infiltrates (≥50% field area; GC-rich areas ), and 5 with <50% GC infiltration (non-GC-rich areas) were registered. In the obtained pictures (442x 248 μm) all plasma cells were manually counted. Results At baseline, the patients were 21-86 years old (mean 58.8, median 42 yrs). All but one patient carried at least one N370S mutated GBA1 allele. Four were previously splenectomized; only one of the remainder group had no splenomegaly. Three patients had anemia, and 10 thrombocytopenia; one patient was not cytopenic. Ten patients had hyperferritinemia but only 2 had mildly increased IL-6 levels (Tab. 1). Proteinogram studies identified M-protein in only 2 subjects, with oligoclonal Ig increase in 2, and polyclonal Ig in 3 patients. Decreased Ig levels were found in 2 patients. Morphological analysis revealed multifocal, compact to dispersed Gaucher cell infiltrates, in all patients, with markedly varying GC burden. Notably, plasma cells were found in higher frequency in GC-rich areas (range 26.2-174.2/HPF), where their usual perivascular distribution pattern was only partially preserved (Fig. 1). Areas dominated by normal hematopoietic tissue demonstrated a significantly lower plasma cell infiltration (range: 2-128.2/HPF; Fig. 2). In patient 5, PC infiltration level was consistent with myeloma, M-protein was at 32 g/L, and difference in PB burden between GC-rich and non-GC areas was in his BM lower than in other patients. Follow up BM samples were obtained in 5 patients, 12-14 months from treatment onset. In 4 of those, PC burden decreased in GC-rich areas but increased in areas with dominant normal hematopoiesis (Fig. 3). The longest documented follow-up was in the SRT subject (over 6 years, patient 1), where similar trends could be observed. Patient 4 initially increased PC burden in BM, and patient 5 succumbed to myeloma and MDS shortly after study onset. Conclusion Bone marrow in GD1 demonstrates increased plasma cell density, particularly in areas affected by the disease. This phenomenon seems to be at least partly modified by disease specific therapy, albeit at a slow pace. N370S mutation was associated with dysimmunoglobulinemia but did not coincide with MGUS in most patients; unexpectedly, the myeloma patient was N370S heterozygous. Disclosures No relevant conflicts of interest to declare.

A characterization of Gaucher iPS-derived astrocytes: Potential implications for Parkinson's disease

While astrocytes, the most abundant cells found in the brain, have many diverse functions, their role in the lysosomal storage disorder Gaucher disease (GD) has not been explored. GD, resulting from the inherited deficiency of the enzyme glucocerebrosidase and subsequent accumulation of glucosylceramide and its acylated derivative glucosylsphingosine, has both non-neuronopathic (GD1) and neuronopathic forms (GD2 and 3). Furthermore, mutations in GBA1, the gene mutated in GD, are an important risk factor for Parkinson's disease (PD). To elucidate the role of astrocytes in the disease pathogenesis, we generated iAstrocytes from induced pluripotent stem cells made from fibroblasts taken from controls and patients with GD1, with and without PD. We also made iAstrocytes from an infant with GD2, the most severe and progressive form, manifesting in infancy. Gaucher iAstrocytes appropriately showed deficient glucocerebrosidase activity and levels and substrate accumulation. These cells exhibited varying degrees of astrogliosis, Glial Fibrillary Acidic Protein (GFAP) up-regulation and cellular proliferation, depending on the level of residual glucocerebrosidase activity. Glutamte uptake assays demonstrated that the cells were functionally active, although the glutamine transporter EEAT2 was upregulated and EEAT1 downregulated in the GD2 samples. GD2 iAstrocytes were morphologically different, with severe cytoskeletal hypertrophy, overlapping of astrocyte processes, pronounced up-regulation of GFAP and S100β, and significant astrocyte proliferation, recapitulating the neuropathology observed in patients with GD2. Although astrocytes do not express α-synuclein, when the iAstrocytes were co-cultured with dopaminergic neurons generated from the same iPSC lines, excessive α-synuclein released from neurons was endocytosed by astrocytes, translocating into lysosomes. Levels of aggregated α-synuclein increased significantly when cells were treated with monomeric or fibrillar α-synuclein. GD1-PD and GD2 iAstrocytes also exhibited impaired Cathepsin D activity, leading to further α-synuclein accumulation. Cytokine and chemokine profiling of the iAstrocytes demonstrated an inflammatory response. Thus, in patients with GBA1-associated parkinsonism, astrocytes appear to play a role in α-synuclein accumulation and processing, contributing to neuroinflammation.

Identification of novel splice site mutation IVS9 + 1(G > A) and novel complex allele G355R/R359X in Type 1 Gaucher patients heterozygous for mutation N370S

Gaucher disease is an autosomal recessive lysosomal storage disorder resulting from deficient glucocerebrosidase activity. More than 350 mutations that cause Gaucher disease have been described to date. Novel mutations can potentially provide insight into the glucocerebrosidase structure–function relationship and biochemical basis of the disease. Here, we report the identification of two novel mutations in two unrelated patients with type I (non-neuronopathic) Gaucher disease: 1) a splice site mutation IVS9+1G>A; and (2) a complex allele (cis) G355R/R359X. Both patients have a common N370S mutation in the other allele. The splice site mutation results from an intronic base substitution (G to A, c.1328+1, g.5005) at the donor splice site of exon and intron 9. The complex allele results from two point mutations in exon 8 of glucocerebrosidase (G to C at c.1180, g.4396, and T to C at c. 1192, g.4408) substituting glycine by arginine (G355R) and arginine by a premature termination (R359X), respectively. In order to demonstrate that G355R/R359X are in cis arrangement, PCR-amplified glucocerebrosidase exon 8 genomic DNA from the patient was cloned into the vector pJET1.2 in Escherichia coli TOP10® strain. Out of the 15 clones that were sequence analyzed, 10 contained the normal allele sequence and 5 contained the complex allele G355R/R359X sequence showing both mutations in cis arrangement. Restriction fragment length polymorphism analysis using Hph1 restriction endonuclease digest was established for the IVS9+1G>A mutation for confirmation and efficient identification of this mutation in future patients. Past literature suggests that mutations affecting splicing patterns of the glucocerebrosidase transcript as well as mutations in Gaucher complex alleles are detrimental to enzyme activity. However, compound heterozygosity with N370S, a mild mutation, will lead to a mild phenotype. The cases reported here support these past findings.

Estimation of Biomarkers Chitotriosidase and CCL18/PARC in Gaucher Patients: Indian Experience

Gaucher disease (GD) is caused by a deficient activity of the enzyme glucocerebrosidase. Recent review from India suggests GD to constitute 14.6 % of all LSD’s. Chitotriosidase has been used for assessing the disease burden and response to enzyme replacement therapy in most of developed countries and in few centers in our country. This biomarker is of limited utility in cases who have inherited mutated chitotriosidase gene, leading to normal to low level of biomarker and thus not correlating with disease burden. CCL18/PARC is a relatively new biomarker which had not been estimated in gaucher patients in India. This study tends to measure quantity of CCL18/PARC in Gaucher patients at various time intervals. The study was conducted at a tertiary care center in North India. Fourteen patients with deficient glucocerebrosidase activity were enrolled as cases. Clinical and biochemical parameters were recorded in predefined proforma. Enzyme glucocerebrosidasae was estimated as per protocol. The level of enzyme Chitotriosidase, CCL18/PARC was performed by using a commercially available ELISA kit. We evaluated chitotriosidase and CLL18/PARC levels in plasma of 10 type 1 GD patients, two with type 2 GD and two with type 3 GD. The median level of chitotriosidase were 259.3 (182–452.1) ng/ml at the time of recruitment {base line}, 332 (216.3–422.5) ng/ml, {1 year after base line}, 331.35 (222.2–434.6) ng/ml {2 years after base line}. The median levels of CCL18/PARC were 484.1 (334.2–592.5) ng/ml at the time of recruitment (baseline), 448.2 (399.2–702) ng/ml, {1 year after base line}, 431.75(362.1–689) ng/ml {2 years after base line}.We conclude that plasma CCL18 levels can serve as a dependable biomarker in patients with Gaucher disease and of significant utility in patients deficient in chitotriosidase enzyme.

Two novel mutations in glucocerebrosidase, C23W and IVS7 − 1 G > A, identified in Type 1 Gaucher patients heterozygous for N370S

Gaucher disease is an autosomal recessive lysosomal storage disorder resulting from deficient glucocerebrosidase activity. There have been nearly 300 mutations described to date. Novel mutations can potentially provide insight into the biochemical basis of the disease. Two novel mutations are described in two Type 1 Gaucher patients with N370S compound heterozygosity; a point mutation that causes an amino acid substitution at cysteine residue 23 for tryptophan, and a second point mutation within the splicing element at the 3′ end of intron 7. Both mutations were identified by PCR amplification and sequence analysis of patient glucocerebrosidase genomic DNA. Restriction fragment length polymorphism analysis was established for both novel mutations for efficient identification in future patients. Past literature suggests that mutations affecting cysteine residues involved in disulfide bridges, as well as mutations affecting splicing patterns of the glucocerebrosidase transcript, are detrimental to enzyme activity. However, compound heterozygosity with N370S, a mild mutation, will lead to a mild phenotype. The cases reported here support these past findings.

An evidence-based review of the potential benefits of taliglucerase alfa in the treatment of patients with Gaucher disease

Gaucher disease is an inherited lysosomal storage disorder, characterized by deficient activity of glucocerebrosidase leading to storage of glucocerebroside in tissue macrophages. Type I disease, the most prevalent form, lacks central nervous system involvement but presents primarily with variable degrees of hepatosplenomegaly, cytopenia, and bone disease. Intravenous enzyme replacement therapy can reverse these manifestations. In addition to the two enzymes currently authorized for use, the newest enzyme, taliglucerase alfa, is at the late stages of clinical development. Taliglucerase alfa is a unique product, as it is the first plant cell–based recombinant enzyme therapy. This review considers the existing evidence for therapeutic efficacy of taliglucerase alfa in the treatment of the non-neuronopathic manifestations of Gaucher disease. Clinical studies encompass one phase I trial in healthy volunteers, one phase III trial, and preliminary results from both an extension study and a switch study. In the 9-month, randomized, double-blind phase III trial, treatment-naïve patients with type I Gaucher disease were treated with either 30 or 60 U/kg every 2 weeks. Dose-dependent improvements were achieved after 6 and 9 months of therapy, with reductions in spleen and liver volumes and improvements in hemoglobin levels. Platelet counts improved initially only in the higher-dose group, but preliminary results from the extension study also show significant increases in the lower-dose group. Bone marrow involvement, as assessed by magnetic resonance imaging, improved in almost all patients. Taliglucerase alfa has shown a good safety profile, with few patients experiencing hypersensitivity reactions and developing antibodies. An additional enzyme replacement therapy for Gaucher disease would enable the treatment of more patients and would provide backup for unexpected production problems. Furthermore, it is expected that this new treatment would reduce the costs of therapy. Taliglucerase alfa is a valuable new treatment modality for the non-neuronopathic manifestations of Gaucher disease.

Gaucher disease in Mexico. Epidemiologic overview

Introduction: Gaucher disease (GD) is a rare genetic recessive autosomical lysosomal storage disease, characterized by deficient activity of glucocerebrosidase. Treatment is available, but a lack of legislation for it in Mexico limits its use. This report describes the clinical features of a Mexican sample of affected subjects. Material and Methods: Sixty-three confirmed patients registered in the Mexican Gaucher Association from 1983-2006 were studied. Age, sex, type, mutation, manifestations, and treatment were evaluated. There were 32 males (50.7%) and 31 females (49.3%); mean age was 21.8 years. Results: Type 1 GD affected 51 (80.9%) and type 3 affected 12 (19.1%) patients. Average age at diagnosis was 12.4 years. Thirty-seven patients were N370S heterozygotes and 6 patients were N370S homozygotes. L444P was found in 14 heterozygote patients and in 6 L444P homozygotes. No L444P homozygote was reported in patients with type 1 GD, and no N370S was observed in patients with type 3 GD. Clinical manifestations were reported in the following percentages of patients: hepatomegaly, 19.04%; hepatosplenomegaly, 80.9%; hematological disorder 58.7%; bone disorder, 100%; neurological disorder, 19.04%. Only 40 (63.4) were under enzyme replacement therapy. Discussion: This is the first complete report of patients with GD in Mexico. Rare disease and orphan drug legislation is needed in Mexico.

The neurological manifestations of Gaucher disease type 1: the French Observatoire on Gaucher disease (FROG)

Gaucher disease (GD), the most prevalent inherited lysosomal storage disorder, is caused by deficient glucocerebrosidase activity. Type 1 GD (GD1), the most common variant, is classically considered non-neuronopathic. We performed a national cross-sectional observational survey-the French Observatoire on Gaucher Disease (FROG)-in patients with GD1 between March 2005 and September 2006. The study included all patients over 18 years of age with confirmed GD1 who attended participating centers for regular follow-up. One hundred and five patients were included, in whom we studied the prevalence and characteristics of relevant neurological symptoms associated with the neuraxis. Of these, 51 (49%) GD1 patients presented at least one neurological symptom. Four patients (4%) had Parkinson disease and 22 (21%) presented with at least one parkinsonian sign or at least one sign frequently associated with Parkinson disease. Five patients (5%) had a previous diagnosis of peripheral neuropathy. Other central nervous system symptoms were recorded in 20 (19%) patients and other peripheral nervous system symptoms in 39 (37%) patients. These data challenge the current classification of GD, and suggest that the three forms of GD each involve a different profile of neurological manifestations.

Gaucher disease: a model disorder for biomarker discovery

Gaucher disease is an inherited lysosomal storage disorder, characterized by massive accumulation of glucosylceramide-laden macrophages in the spleen, liver and bone marrow as a consequence of deficient activity of glucocerebrosidase. Gaucher disease has been the playground to develop new therapeutic interventions such as enzyme-replacement therapy and substrate-reduction therapy. The availability of these costly therapies has stimulated research regarding suitable biomarkers to monitor onset and progression of disease, as well as the efficacy of therapeutic intervention. Given the important role of storage cells in the pathology, various attempts have been made to identify proteins in plasma or serum reflecting the body burden of these pathological cells. In this review, the existing data regarding biomarkers for Gaucher disease, as well as the current application of biomarkers in clinical management of Gaucher patients are discussed. Moreover, the use of several modern proteomic technologies for the identification of Gaucher biomarkers is reviewed.

Myopathy in Gaucher disease

Gaucher disease is a recessively inherited lysosomal storage disorder, caused by deficiency of glucocerebrosidase activity. Affected individuals usually present with hepatosplenomegaly, anaemia, thrombocytopenia, and skeletal diseases. A wide range of neurological manifestations have also been recognized in Gaucher patients including acute neurological deterioration in infancy, mental retardation, ocular motor apraxia, seizure, and parkinsonism. Although muscle weakness is not an uncommon finding in patients with Gaucher disease, the aetiology of weakness is not well understood. We prospectively investigated seven Gaucher patients and found that four of them (patients 1-4) had mild to moderate degree of proximal-predominant symmetrical muscle weakness in four limbs. By history, three patients (patients 1-3) developed insidious onset of nonprogressive muscle weakness in four limbs with easy muscle fatigue from adolescence. A needle electromyographic study detected some small, brief polyphasic waves in these four patients. Muscle biopsy in one patient (patient 1) showed a few atrophic type II muscle fibres without infiltration of Gaucher cells. Three patients (patients 1-3) continuously received enzyme replacement therapy with imiglucerase and their muscle strength seemed improved after two years. We concluded that Gaucher disease may be associated with myopathy.

Analysis and Quantification of Diagnostic Serum Markers and Protein Signatures for Gaucher Disease

Novel approaches for the qualitative and quantitative proteomics analysis by nanoscale LC-MS applied to the study of protein expression response in depleted and undepleted serum of Gaucher patients undergoing enzyme replacement therapy are presented. Particular emphasis is given to the method reproducibility of these LC-MS experiments without the use of isotopic labels. The level of chitotriosidase, an established Gaucher biomarker, was assessed by means of an absolute concentration determination technique for alternate scanning LC-MS generated data. Disease associated proteins, including fibrinogens, complement cascade proteins, and members of the high density lipoprotein serum content, were recognized by various clustering methods and sorting and intensity profile grouping of identified peptides. Condition-unique LC-MS protein signatures could be generated utilizing the measured serum protein concentrations and are presented for all investigated conditions. The clustering results of the study were also used as input for gene ontology searches to determine the correlation between the molecular functions of the identified peptides and proteins.

Les manifestations neurologiques de la maladie de Gaucher de type 1 : vers une remise en cause de la classification actuelle ?

Gaucher's disease (GD), the most prevalent inherited lysosomal storage disorder, is caused by deficient glucocerebrosidase activity. The resulting accumulation of glucocerebrosides in lysosomes of macrophages leads to hepatosplenomegaly, anemia, thrombocytopenia, and various bone manifestations. Gaucher's disease is classified into 3 types based on the nature of its effects on the central nervous system. Type 1, the most common variant, is classically nonneuronopathic. However, the occurrence of Parkinsonism seems to be more frequent in type I Gaucher's disease than in the general population. Furthermore, heterozygotes for certain glucocerebrosidase gene mutations have a higher risk to develop Parkinson's disease. We report our experience about 9 patients with Gaucher's disease and their association with neurological manifestations. These recent data may discuss Gaucher's classification and the existence of a continuum between neurologic and non-neurologic forms of the disease.

Hydrophilic iminosugar active‐site‐specific chaperones increase residual glucocerebrosidase activity in fibroblasts from Gaucher patients

Gaucher disease is an autosomal recessive lysosomal storage disorder caused by the deficient activity of glucocerebrosidase. Accumulation of glucosylceramide, primarily in the lysosomes of cells of the reticuloendothelial system, leads to hepatosplenomegaly, anemia and skeletal lesions in type I disease, and neurologic manifestations in types II and III disease. We report herein the identification of hydrophilic active-site-specific chaperones that are capable of increasing glucocerebrosidase activity in the cultured fibroblasts of Gaucher patients. Screening of a variety of natural and synthetic alkaloid compounds showed isofagomine, N-dodecyl deoxynojirimycin, calystegines A3, B1, B2 and C1, and 1,5-dideoxy-1,5-iminoxylitol to be potent inhibitors of glucocerebrosidase. Among them, isofagomine was the most potent inhibitor of glucocerebrosidase in vitro, and the most effective active-site-specific chaperone capable of increasing residual glucocerebrosidase activity in fibroblasts established from Gaucher patients with the most prevalent Gaucher disease-causing mutation (N370S). Intracellular enzyme activity increased approximately two-fold after cells had been incubated with isofagomine, and the increase in glucocerebrosidase activity was both dose-dependent and time-dependent. Western blotting demonstrated that there was a substantial increase in glucocerebrosidase protein in cells after isofagomine treatment. Immunocytochemistry revealed an improvement in the glucocerebrosidase trafficking pattern, which overlaps that of lysosome-associated membrane protein 2 in Gaucher fibroblasts cultivated with isofagomine, suggesting that the transport of mutant glucocerebrosidase is at least partially improved in the presence of isofagomine. The hydrophilic active-site-specific chaperones are less toxic to cultured cells. These results indicate that these hydrophilic small molecules are suitable candidates for further drug development for the treatment of Gaucher disease.

Gaucher Disease-Associated Glucocerebrosidases Show Mutation-Dependent Chemical Chaperoning Profiles

Gaucher disease is a lysosomal storage disorder caused by deficient glucocerebrosidase activity. We have previously shown that the cellular activity of the most common Gaucher disease-associated glucocerebrosidase variant, N370S, is increased when patient-derived cells are cultured with the chemical chaperone N-nonyl-deoxynojirimycin. Chemical chaperones stabilize proteins against misfolding, enabling their trafficking from the endoplasmic reticulum. Herein, the generality of this therapeutic strategy is evaluated with other glucocerebrosidase variants and with additional candidate chemical chaperones. Improved chemical chaperones are identified for N370S glucocerebrosidase. Moreover, we demonstrate that G202R, a glucocerebrosidase variant that is known to be retained in the endoplasmic reticulum, is also amenable to chemical chaperoning. The L444P variant is not chaperoned by any of the active site-directed molecules tested, likely because this mutation destabilizes a domain distinct from the catalytic domain.

CASE REPORT: Novel Point Mutation (W184R) in Neonatal Type 2 Gaucher Disease

Gaucher disease is the most prevalent inherited sphingolipidosis and results from deficient glucocerebrosidase activity. Three clinical forms of Gaucher disease have been described: type 1, or non-neuronopathic; type 2, or acute neuronopathic; and type 3, or subacute neuronopathic. We have identified a novel mutation in a patient of Russian-British descent who died of type 2 Gaucher disease a few hours after birth. A heterozygous T → C transition mutation in exon 6, cDNA nucleotide position 667, results in the substitution of tryptophan by arginine at amino acid residue 184 (W184R) of glucocerebrosidase. This mutation creates a new cleavage site for the restriction endonuclease Hinf1. We developed a method that utilizes Hinf1 restriction endonuclease analysis to confirm the presence of the mutation and test family members. The second mutation identified in the other glucocerebrosidase allele of the patient is mutation L444P, a severe mutation frequent in type 2 and 3 Gaucher disease. Since the patient died very shortly after birth, we postulate that the W184R/L444P genotype may result in little or no detectable glucocerebrosidase activity and thus a poor prognosis.

Differential Effects of Enzyme Supplementation Therapy on Manifestations of Type 1 Gaucher Disease

BACKGROUND: In type 1 Gaucher disease (GD), the accumulation of glucocerebroside in macrophages, caused by deficient activity of glucocerebrosidase, results in a variety of disease manifestations. In addition to the characteristic features of hepatosplenomegaly, cytopenia, and bone abnormalities, resting energy expenditure (REE) and glucose production are increased. In this study the effects of enzyme supplementation therapy on metabolic parameters in relation to other disease manifestations in type 1 GD patients are investigated.PATIENTS AND METHODS: In 12 adult type 1 GD patients, measurements of REE (by indirect calorimetry), liver and spleen volume (by spiral computerized axial tomography [CT]) and hemoglobin and platelet count were obtained before and after 6 months of alglucerase therapy (15 U/kg per month). In 7 of the 12 patients hepatic glucose production was measured by infusing 3-3H glucose. For comparison, REE and glucose metabolism were studied in 7 weight- and age-matched healthy subjects.RESULTS: REE and glucose production were increased in GD patients as compared with controls (REE: 29.8 kcal/kg/24 h ± 3.6 and 23.1 ± 2.3 kcal/kg/24 h, respectively, P < 0.05; glucose production: 14.00 μmol/kg/min ± 0.51 and 10.77 μmol/kg/min ± 0.26, respectively, P < 0.03). There were no differences in plasma glucose concentrations. Whereas the elevated REE decreased after 6 months of alglucerase therapy from 129% to 120% of predicted values (P < 0.01), the increase in hepatic glucose production did not change. An increase in weight occurred after 6 months of treatment (1.7 ± 0.8 kg, P < 0.001), which was accounted for by an increase in fat mass of 1.6 ± 1.5 kg (P < 0.02). Hemoglobin levels increased from 11.2 mg/dL to 12.1 mg/dL (P = 0.05) and platelet counts rose from 84 × 109/L to 113 × 109/L (P < 0.05). Although liver and spleen volumes decreased by ∼10% and ∼20%, respectively, there was no correlation between the decrease in organ volumes and the decrease in REE.CONCLUSIONS: Treatment with alglucerase improves hypermetabolism and organomegaly in GD, whereas the increase in glucose production persists. Therefore, the dose-response effects of alglucerase are variable for the different manifestations of type 1 GD.

Gaucher disease: molecular screening of the glucocerebrosidase 1601G and 1601A alleles in Victoria, British Columbia, Canada.

Gaucher disease is the most prevalent lysosomal storage disease and it results from inherited deficient glucocerebrosidase activity. The glucocerebrosidase gene from normal people was sequenced by several laboratories and it...

Gaucher disease: Functional expression of the normal glucocerebrosidase and Gaucher T1366G and G1604A alleles in Baculovirus‐transfected Spodoptera frugiperda cells

Gaucher disease is an inherited sphingolipidosis resulting from deficient glucocerebrosidase activity. Three clinical forms of Gaucher disease have been described: type 1 as non-neuronopathic, type 2 as acute neuronopathic, and type 3 as subacute neuronopathic. We recently identified a rare mutation (G→A at glucocerebrosidase cDNA nucleotide position 1604) [Choy et al., 1994a, Am J Med Genet 51:156–160] and a novel mutation (T→G at glucocerebrosidase cDNA nucleotide position 1366) in two type 1 Gaucher patients by sequence analysis of the entire glucocerebrosidase coding region [Choy et al., 1994a, 1994b, Hum Mol Genet 3:821–823]. To demonstrate that these are deleterious and not neutral mutations, we cloned the full-length glucocerebrosidase cDNA of patients and of a normal control in the plasmid vector pAcUW1, recombined the human gene into the Baculovirus genome downstream of its polyhedron p10 promoter, and expressed the inserted gene in cultured cells of Spodoptera frugiperda transfected by recombinant Baculovirus. The levels of residual glucocerebrosidase activity determined in transfected cells with the Gaucher G1604A and T1366G alleles are 6.9% and 2.9% of that expressed by the normal allele (normal = 352.0 nmol/hr/mg protein or 100%). By comparison, the enzyme-specific activity expressed in transfected cells by 2 known Gaucher alleles, A1226G and T1448C, that are prevalent in type 1 and type 2 Gaucher disease are 23.4% and 3.3% of normal. No endogeneous glucocerebrosidase activity was detected in cultured cells transfected by either the wild-type Baculovirus or Baculovirus with the pAcUW1 plasmid vector without the glucocerebrosidase cDNA insert. These findings show that the Baculovirus expression system in cultured Spodoptera frugiperda cells is a suitable system for the functional expression and characterization of the normal and mutant glucocerebrosidase alleles. Moreover, the use of this expression system demonstrates that the G1604A and T1366G mutations are both deleterious mutations resulting in profoundly deficient glucocerebrosidase activity and subsequent Gaucher disease. © 1996 Wiley-Liss, Inc.