Phenotypic continuum in neuronopathic Gaucher disease: an intermediate phenotype between type 2 and type 3

Phenotypic consequences of GBA1 pathological variant R463C (p.R502C)

Gaucher disease (GD) is an autosomal recessively inherited lysosomal storage disorder caused by biallelic pathological variants in the GBA1 gene. Patients present along a broad clinical spectrum, and phenotypes are often difficult to predict based on genotype alone. The variant R463C (p.Arg502Cys) exemplifies this challenge. To better characterize its different clinical presentations, we examined the records of 25 current and historical patients evaluated at the National Institutes of Health. Nine patients were classified as GD1, 14 were classified as GD3, and two had an ambiguous diagnosis between GD1 and GD3. In addition, we reviewed the published literature in PubMed and Web of Science through December 2023, identifying 62 cases with an R463C variant from 18 countries. Within the NIH cohort, the most common second variants were N370S (p.N409S) and L444P (p.L483P). R463C/L444P was encountered in patients with GD1 and GD3 in both the NIH cohort and worldwide. In the literature, R463C/R463C was also reported in both GD1 and GD3, although sparse phenotypic information was shared. Often the phenotype reflected what might be predicted for the second mutant allele. This diversity of phenotypes emphasizes the need for longitudinal follow-up to assess symptom development and neurological involvement.

Comparison of different promoters to improve AAV vector-mediated gene therapy for neuronopathic Gaucher disease

Gaucher Disease (GD) is an inherited metabolic disorder caused by mutations in the GBA1 gene. It can manifest with severe neurodegeneration and visceral pathology. The most acute neuronopathic form (nGD), for which there are no curative therapeutic options, is characterised by devastating neuropathology and death during infancy. In this study, we investigated the therapeutic benefit of systemically delivered AAV9 vectors expressing the human GBA1 gene at two different doses comparing a neuronal-selective promoter with ubiquitous promoters. Our results highlight the importance of a careful evaluation of the promoter sequence used in gene delivery vectors, suggesting a neuron-targeted therapy leading to high levels of enzymatic activity in the brain but lower GCase expression in the viscera, might be the optimal therapeutic strategy for nGD.

Presentation of ichthyosis after substrate reduction therapy in Gaucher type 1

We describe a case in which a type 1 Gaucher patient developed ichthyosis weeks after starting substrate reduction therapy (SRT) with eliglustat. There are no reports of ichthyosis in the literature in enzyme replacement or SRT for Gaucher disease. Ichthyosis is seen with type 2 and 3 Gaucher disease, but not type 1. This raises the question: Why would a patient develop ichthyosis after starting SRT?

A review of type 3 Gaucher disease: unique neurological manifestations and advances in treatment

Gaucher disease (GD) is a rare lysosomal storage disease that is caused by mutations in the GBA gene. It is classified into three main phenotypes according to the patient's clinical presentation. Of these, chronic neuronopathic GD (GD3) is characterized by progressive neurological damage. Understanding the unique neurological manifestations of GD3 has important diagnostic and therapeutic implications. Our article summarizes the neurological symptoms specific to GD3 and related therapeutic advances, and it highlights the relevance of the gene to clinical symptoms, so as to provide a reference for the diagnosis and treatment of GD3.

Twelve Years of the Gaucher Outcomes Survey (GOS): Insights, Achievements, and Lessons Learned from a Global Patient Registry

Background: Long-term patient registries are important for evaluating treatment outcomes in patients with rare diseases, and can provide insights into natural disease history and progression in real-world clinical practice. Initiated in 2010, the Gaucher Outcome Survey (GOS) is an ongoing, international, multicenter, observational registry (ClinicalTrials.gov Identifier: NCT03291223) for patients with a diagnosis of Gaucher disease (GD), irrespective of treatment type or status, with a primary objective to monitor safety and long-term effectiveness of velaglucerase alfa. Methods: Here, we evaluated the GOS population 12 years after the registry initiation. Results: As of 25 February 2023, 2084 patients enrolled in the GOS and 1643 received GD-specific treatment. Patients exhibited broad heterogeneity at baseline: age of diagnosis (0 to 85.3 years), hemoglobin concentrations (<80.0 g/L to >150 g/L), platelet counts (<50 × 109/L to >450 × 109/L), and liver and spleen volumes. Most patients treated with enzyme replacement therapy or substrate reduction therapy reported improvements in clinical parameters within 1 year of treatment initiation, maintained over the course of treatment up to 12 years, whereas untreated patients had baseline values closer to standard reference thresholds and showed stability over time. Conclusion: The 12-year data from the GOS confirm the impact of long-term treatment with GD-specific agents and offer insights into disease progression and outcomes in a real-world setting.

An increase in ER stress and unfolded protein response in iPSCs-derived neuronal cells from neuronopathic Gaucher disease patients

Gaucher disease (GD) is a lysosomal storage disorder caused by a mutation in the GBA1 gene, responsible for encoding the enzyme Glucocerebrosidase (GCase). Although neuronal death and neuroinflammation have been observed in the brains of individuals with neuronopathic Gaucher disease (nGD), the exact mechanism underlying neurodegeneration in nGD remains unclear. In this study, we used two induced pluripotent stem cells (iPSCs)-derived neuronal cell lines acquired from two type-3 GD patients (GD3-1 and GD3-2) to investigate the mechanisms underlying nGD by biochemical analyses. These iPSCs-derived neuronal cells from GD3-1 and GD3-2 exhibit an impairment in endoplasmic reticulum (ER) calcium homeostasis and an increase in unfolded protein response markers (BiP and CHOP), indicating the presence of ER stress in nGD. A significant increase in the BAX/BCL-2 ratio and an increase in Annexin V-positive cells demonstrate a notable increase in apoptotic cell death in GD iPSCs-derived neurons, suggesting downstream signaling after an increase in the unfolded protein response. Our study involves the establishment of iPSCs-derived neuronal models for GD and proposes a possible mechanism underlying nGD. This mechanism involves the activation of ER stress and the unfolded protein response, ultimately leading to apoptotic cell death in neurons.

Potential Binding Sites of Pharmacological Chaperone NCGC00241607 on Mutant β-Glucocerebrosidase and Its Efficacy on Patient-Derived Cell Cultures in Gaucher and Parkinson's Disease

Mutations in the GBA1 gene, encoding the lysosomal enzyme glucocerebrosidase (GCase), cause Gaucher disease (GD) and are the most common genetic risk factor for Parkinson's disease (PD). Pharmacological chaperones (PCs) are being developed as an alternative treatment approach for GD and PD. To date, NCGC00241607 (NCGC607) is one of the most promising PCs. Using molecular docking and molecular dynamics simulation we identified and characterized six allosteric binding sites on the GCase surface suitable for PCs. Two sites were energetically more preferable for NCGC607 and located nearby to the active site of the enzyme. We evaluated the effects of NCGC607 treatment on GCase activity and protein levels, glycolipids concentration in cultured macrophages from GD (n = 9) and GBA-PD (n = 5) patients as well as in induced human pluripotent stem cells (iPSC)-derived dopaminergic (DA) neurons from GBA-PD patient. The results showed that NCGC607 treatment increased GCase activity (by 1.3-fold) and protein levels (by 1.5-fold), decreased glycolipids concentration (by 4.0-fold) in cultured macrophages derived from GD patients and also enhanced GCase activity (by 1.5-fold) in cultured macrophages derived from GBA-PD patients with N370S mutation (p < 0.05). In iPSC-derived DA neurons from GBA-PD patients with N370S mutation NCGC607 treatment increased GCase activity and protein levels by 1.1-fold and 1.7-fold (p < 0.05). Thus, our results showed that NCGC607 could bind to allosteric sites on the GCase surface and confirmed its efficacy on cultured macrophages from GD and GBA-PD patients as well as on iPSC-derived DA neurons from GBA-PD patients.

Classification of GBA1 Variants in Parkinson's Disease: The GBA1-PD Browser

BACKGROUND

GBA1 variants are among the most common genetic risk factors for Parkinson's disease (PD). GBA1 variants can be classified into three categories based on their role in Gaucher's disease (GD) or PD: severe, mild, and risk variant (for PD).

OBJECTIVE

This review aims to generate and share a comprehensive database for GBA1 variants reported in PD to support future research and clinical trials.

METHODS

We performed a literature search for all GBA1 variants that have been reported in PD. The data have been standardized and complemented with variant classification, odds ratio if available, and other data.

RESULTS

We found 371 GBA1 variants reported in PD: 22 mild, 84 severe, 3 risk variants, and 262 of unknown status. We created a browser containing up-to-date information on these variants (https://pdgenetics.shinyapps.io/GBA1Browser/).

CONCLUSIONS

The classification and browser presented in this work should inform and support basic, translational, and clinical research on GBA1-PD. © 2023 International Parkinson and Movement Disorder Society.

Glucosylsphingosine (Lyso-Gb1) as a reliable biomarker in Gaucher disease: a narrative review

BACKGROUND

Gaucher disease (GD) is a rare, inherited, autosomal recessive disorder caused by a deficiency of the lysosomal enzyme, acid β-glucosidase. Its diagnosis is achieved via measurements of acid β-glucosidase activity in either fresh peripheral blood leukocytes or dried blood spots, and confirmed by identifying characteristic mutations in the GBA1 gene. Currently, several biomarkers are available for disease monitoring. Chitotriosidase has been used over the last 20 years to assess the severity of GD, but lacks specificity in GD patients. Conversely, the deacylated form of glucosylceramide, glucosylsphingosine (also known as lyso-Gb1), represents a more reliable biomarker characterized by its high sensitivity and specificity in GD.

MAIN TEXT

Herein, we review the current literature on lyso-Gb1 and describe evidence supporting its usefulness as a biomarker for diagnosing and evaluating disease severity in GD and monitoring treatment efficacy.

CONCLUSION

Lyso-Gb1 is the most promising biomarker of GD, as demonstrated by its reliability in reflecting disease burden and monitoring treatment response. Furthermore, lyso-Gb1 may play an important role in the onset of monoclonal gammopathy of uncertain significance, multiple myeloma, and Parkinson's disease in GD patients.

Glucocerebrosidase mutations and Parkinson disease

The discovery of glucocerebrosidase (GBA1) mutations as the greatest numerical genetic risk factor for the development of Parkinson disease (PD) resulted in a paradigm shift within the research landscape. Efforts to elucidate the mechanisms behind GBA1-associated PD have highlighted shared pathways in idiopathic PD including the loss and gain-of-function hypotheses, endoplasmic reticulum stress, lipid metabolism, neuroinflammation, mitochondrial dysfunction and altered autophagy-lysosomal pathway responsible for degradation of aggregated and misfolded a-synuclein. GBA1-associated PD exhibits subtle differences in phenotype and disease progression compared to idiopathic counterparts notably an earlier age of onset, faster motor decline and greater frequency of non-motor symptoms (which also constitute a significant aspect of the prodromal phase of the disease). GBA1-targeted therapies have been developed and are being investigated in clinical trials. The most notable are Ambroxol, a small molecule chaperone, and Venglustat, a blood-brain-barrier-penetrant substrate reduction therapy agent. It is imperative that further studies clarify the aetiology of GBA1-associated PD, enabling the development of a greater abundance of targeted therapies in this new era of precision medicine.

Switching between Enzyme Replacement Therapies and Substrate Reduction Therapies in Patients with Gaucher Disease: Data from the Gaucher Outcome Survey (GOS)

Switching between enzyme replacement therapies (ERT) and substrate reduction therapies (SRT) in patients with type 1 Gaucher disease (GD1) is not uncommon; however, the reasons for switchng treatments have not been explored in detail. Data from the Gaucher Outcome Survey (GOS), an international registry for patients with confirmed GD, were used to evaluate the reasons for, and consequences of, switching between these treatment types. Of the 1843 patients enrolled in GOS on 25 February 2020, 245 had undergone a treatment switch: 222 from initial ERT to SRT (of whom 88 later switched back to ERT) and 23 from initial SRT to ERT. The most common reasons for ERT–SRT switching were duration of infusion (25.4%), drug shortage (22.0%), and adverse events (AEs; 11.9%), and for SRT–ERT switching, AEs (63.6%), lack of beneficial effect (16.4%), and participation in a clinical trial (9.1%). Bodyweight and hematologic parameters largely remained stable before and after switching between ERT and SRT, although with substantial variation between patients. These findings contribute to understanding why treatment switching occurs in patients with GD, and may help physicians recognize the real-world impact of treatment switching between ERT and SRT for patients with GD.

Neuronopathic Gaucher disease: Beyond lysosomal dysfunction

Gaucher disease (GD) is an inherited disorder caused by recessive mutations in the GBA1 gene that encodes the lysosomal enzyme β-glucocerebrosidase (β-GC). β-GC hydrolyzes glucosylceramide (GluCer) into glucose and ceramide in the lysosome, and the loss of its activity leads to GluCer accumulation in different tissues. In severe cases, enzymatic deficiency triggers inflammation, organomegaly, bone disease, and neurodegeneration. Neuronopathic Gaucher disease (nGD) encompasses two different forms of the disease, characterized by chronic or acute damage to the central nervous system (CNS). The cellular and molecular studies that uncover the pathological mechanisms of nGD mainly focus on lysosomal dysfunction since the lysosome is the key organelle affected in GD. However, new studies show alterations in other organelles that contribute to nGD pathology. For instance, abnormal accumulation of GluCer in lysosomes due to the loss of β-GC activity leads to excessive calcium release from the endoplasmic reticulum (ER), activating the ER-associated degradation pathway and the unfolded protein response. Recent evidence indicates mitophagy is altered in nGD, resulting in the accumulation of dysfunctional mitochondria, a critical factor in disease progression. Additionally, nGD patients present alterations in mitochondrial morphology, membrane potential, ATP production, and increased reactive oxygen species (ROS) levels. Little is known about potential dysfunction in other organelles of the secretory pathway, such as the Golgi apparatus and exosomes. This review focuses on collecting evidence regarding organelle dysfunction beyond lysosomes in nGD. We briefly describe cellular and animal models and signaling pathways relevant to uncovering the pathological mechanisms and new therapeutic targets in GD.

Promising Effect of High Dose Ambroxol Treatment on Neurocognition and Motor Development in a Patient With Neuropathic Gaucher Disease 2

Gaucher Disease (GD) 2 is a rare inherited lysosomal disorder. Early-onset and rapid progression of neurovisceral symptoms lead to fatal outcome in early childhood. Treatment is symptomatic, a curative therapy is currently not available. This prospective study describes the clinical and biochemical outcome of a GD 2 patient treated with high dose ambroxol from the age of 4 months. Due to progressive hepatosplenomegaly additional enzyme replacement therapy was required 1 year after ambroxol monotherapy was initiated. Detailed clinical follow-up data demonstrated an age-appropriate neurocognitive and motor development but no clear benefit on peripheral organs. Glucosylsphingosine (Lyso-GL1) in cerebrospinal fluid decreased remarkably compared to pre-treatment, whereas Lyso-GL1 and chitotriosidase in blood increased. Ambroxol treatment of patient fibroblasts revealed a significant increase in β-glucocerebrosidase activity in vitro. To our knowledge, this is the first report of a GD 2 patient with age-appropriate cognitive and motor development at 3 years of age. Combination of high dose ambroxol with ERT proved to be a successful approach to manage both visceral and neurological manifestations.

Gene Therapy for Parkinson's Disease Associated with GBA1 Mutations

Human genetic studies as well as studies in animal models indicate that lysosomal dysfunction plays a key role in the pathogenesis of Parkinson's disease. Among the lysosomal genes involved, GBA1 has the largest impact on Parkinson's disease risk. Deficiency in the GBA1 encoded enzyme glucocerebrosidase (GCase) leads to the accumulation of the GCase glycolipid substrates glucosylceramide and glucosylsphingosine and ultimately results in toxicity and inflammation and negatively affect many clinical aspects of Parkinson's disease, including disease risk, the severity of presentation, age of onset, and likelihood of progression to dementia. These findings support the view that re-establishing normal levels of GCase enzyme activity may reduce the progression of Parkinson's disease in patients carrying GBA1 mutations. Studies in mouse models indicate that PR001, a AAV9 vector-based gene therapy designed to deliver a functional GBA1 gene to the brain, suggest that this therapeutic approach may slow or stop disease progression. PR001 is currently being evaluated in clinical trials with Parkinson's disease patients carrying GBA1 mutations.

Development and validation of Gaucher disease type 1 (GD1)-specific patient-reported outcome measures (PROMs) for clinical monitoring and for clinical trials

BACKGROUND

Disease-specific patient-reported outcome measures (PROMs) are fundamental to understanding the impact on, and expectations of, patients with genetic disorders, and can facilitate constructive and educated conversations about treatments and outcomes. However, generic PROMs may fail to capture disease-specific concerns. Here we report the development and validation of a Gaucher disease (GD)-specific PROM for patients with type 1 Gaucher disease (GD1) a lysosomal storage disorder characterized by hepatosplenomegaly, thrombocytopenia, anemia, bruising, bone disease, and fatigue.

RESULTS AND DISCUSSION

The questionnaire was initially developed with input from 85 patients or parents of patients with GD1 or GD3 in Israel. Owing to few participating patients with GD3, content validity was assessed for patients with GD1 only. Content validity of the revised questionnaire was assessed in 33 patients in the US, France, and Israel according to US Food and Drug Administration standards, with input from a panel of six GD experts and one patient advocate representative. Concept elicitation interviews explored patient experience of symptoms and treatments, and a cognitive debriefing exercise explored patients' understanding and relevance of instructions, items, response scales, and recall period. Two versions of the questionnaire were subsequently developed: a 24-item version for routine monitoring in clinical practice (rmGD1-PROM), and a 17-item version for use in clinical trials (ctGD1-PROM). Psychometric validation of the ctGD1-PROM was assessed in 46 adult patients with GD1 and re-administered two weeks later to examine test-retest reliability. Findings from the psychometric validation study revealed excellent internal consistency and strong evidence of convergent validity of the ctGD1-PROM based on correlations with the 36-item Short Form Health Survey. Most items were found to show moderate, good, or excellent test-retest reliability.

CONCLUSIONS

Development of the ctGD1-PROM represents an important step forward for researchers measuring the impact of GD and its respective treatment.

Investigation of a dysmorphic facial phenotype in patients with Gaucher disease types 2 and 3

Gaucher disease (GD) is a rare lysosomal storage disorder that is divided into three subtypes based on presentation of neurological manifestations. Distinguishing between the types has important implications for treatment and counseling. Yet, patients with neuronopathic forms of GD, types 2 and 3, often present at young ages and can have overlapping phenotypes. It has been shown that new technologies employing artificial intelligence and facial recognition software can assist with dysmorphology assessments. Though classically not associated nor previously described with a dysmorphic facial phenotype, this study investigated whether a facial recognition platform could distinguish between photos of patients with GD2 and GD3 and discriminate between them and photos of healthy controls. Each cohort included over 100 photos. A cross validation scheme including a series of binary comparisons between groups was used. Outputs included a composite photo of each cohort and either a receiver operating characteristic curve or a confusion matrix. Binary comparisons showed that the software could correctly group photos at least 89% of the time. Multiclass comparison between GD2, GD3, and healthy controls demonstrated a mean accuracy of 76.6%, compared to a 37.7% chance for random comparison. Both GD2 and GD3 have now been added to the facial recognition platform as established syndromes that can be identified by the algorithm. These results suggest that facial recognition and artificial intelligence, though no substitute for other diagnostic methods, may aid in the recognition of neuronopathic GD. The algorithm, in concert with other clinical features, also appears to distinguish between young patients with GD2 and GD3, suggesting that this tool can help facilitate earlier implementation of appropriate management.

Clinical-genetic characteristics and treatment outcomes of Turkish children with Gaucher disease type 1 and type 3: A sixteen year single-center experience

Data from 38 children were retrospectively analyzed to determine the patient characteristics of Turkish children with Gaucher disease (GD) and evaluate the impact of enzyme replacement therapy (ERT) in a pediatric cohort consisting of two different sub-types of the disease, Gaucher disease type 1 (GD1) and type 3 (GD3). Both types were represented equally (GD1/GD3 = 20/18). L444P (35.5%) was the most common mutant allele while L444P/L444P (34.2%) was the most common genotype overall. Compound heterozygosity of N370S and L444P homozygosity were the dominant genotypes in Turkish children with GD1 and GD3, respectively. None of the patients had moderate to severe thrombocytopenia at last follow-up while the percent of patients with anemia decreased from 60% to 5.7% (p < 0.001). Significant improvements in mean liver (from 2.2 to 1.6 MN, p < 0.001) and spleen (from 15.5 to 7.6 MN, p < 0.001) volumes were observed in the first year of ERT. Linear growth was ameliorated as shown by the decrease in the percent of patients having short stature from 34.3% to 13.3% (p < 0.01) at year 5. Erlenmeyer flask deformity, osteopenia and scoliosis were common skeletal findings. Although none of the patients had lung disease at diagnosis, 20% developed radiological findings suggestive of pulmonary involvement. This single center experience is the first comprehensive study from Turkey not only reporting clinical and genetic characteristics of GD patients but also providing information on the outcomes of ERT in two different sub-types of GD. Genotypic background of Turkish children with GD is similar to western populations. Although visceral and hematological therapeutic goals are reached as early as one year of ERT in both sub-types, achieving normal growth takes several more years than suggested in significant number of children with GD.

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 β-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.

Early initiation of ambroxol treatment diminishes neurological manifestations of type 3 Gaucher disease: A long-term outcome of two siblings

Gaucher disease type 3 (GD3) is a severely debilitating disorder characterized by multisystemic manifestations and neurodegeneration. Enzyme replacement therapy alleviates visceral signs and symptoms but has no effect on neurological features. Ambroxol has been suggested as an enzyme enhancement agent. Some studies have confirmed its effectiveness in preventing the progression of neurological manifestations of neuronopathic Gaucher disease. In this study, we report two GD3 siblings in whom ambroxol combined with enzyme replacement therapy was initiated at different stages of the disease. We demonstrate the enzyme enhancement effect of ambroxol on L444P/H225Q;D409H glucocerebrosidase activity through results of fibroblast studies and long-term clinical outcomes of the two patients. The sibling diagnosed at the age of four-and-a-half years with significant neurological involvement manifested relatively rapid improvement on ambroxol treatment, followed by stabilization of further course. The younger sibling, in whom the treatment was started at seven weeks, displayed attention deficit and low average cognitive functioning at the age of seven years, but did not manifest other neurological symptoms. The difference in neurological outcomes indicates that ambroxol delayed or even halted the evolution of neurological manifestations in the younger sibling. This observation suggests that early initiation of ambroxol treatment may arrest neurological involvement in some GD3 patients.

The Gaucher earlier diagnosis consensus point-scoring system (GED-C PSS): Evaluation of a prototype in Finnish Gaucher disease patients and feasibility of screening retrospective electronic health record data for the recognition of potential undiagnosed patients in Finland

Background

Gaucher disease (GD) is a rare inherited multiorgan disorder, yet a diagnosis can be significantly delayed due to a broad spectrum of symptoms and lack of disease awareness. Recently, the prototype of a GD point-scoring system (PSS) was established by the Gaucher Earlier Diagnosis Consensus (GED-C) initiative, and more recently, validated in Gaucher patients in UK. In our study, the original GED-C PSS was tested in Finnish GD patients. Furthermore, the feasibility of point scoring large electronic health record (EHR) data set by data mining to identify potential undiagnosed GD cases was evaluated.

Methods

This biobank study was conducted in collaboration with two Finnish biobanks. Five previously diagnosed Finnish GD patients and ~ 170,000 adult biobank subjects were included in the study. The original PSS was locally adjusted due to data availability issues and applied to the Finnish EHR data representing special health care recordings.

Results

All GD patients had high levels of the biomarker lyso-Gb1 and deleterious GBA mutations. One patient was a compound heterozygote with a novel variant, potentially pathogenic mutation. Finnish EHR data allowed the retrospective assessment of 27–30 of the 32 original GED-C signs/co-variables. Total point scores of GD patients were high but variable, 6–18.5 points per patient (based on the available data on 28–29 signs/co-variables per patient). All GD patients had been recorded with anaemia while only three patients had a record of splenomegaly. 0.72% of biobank subjects were assigned at least 6 points but none of these potential “GD suspects” had a point score as high as 18.5. Splenomegaly had been recorded for 0.25% of biobank subjects and was associated with variable point score distribution and co-occurring ICD-10 diagnoses.

Discussion

This study provides an indicative GED-C PSS score range for confirmed GD patients, also representing potential mild cases, and demonstrates the feasibility of scoring Finnish EHR data by data mining in order to screen for undiagnosed GD patients. Further prioritisation of the “GD suspects” with more developed algorithms and data-mining approaches is needed.

Funding

This study was funded by Shire (now part of Takeda).

Diagnosing neuronopathic Gaucher disease: New considerations and challenges in assigning Gaucher phenotypes

Gaucher disease (GD), resulting from biallelic mutations in the gene GBA1, is a monogenic recessively inherited Mendelian disorder with a wide range of phenotypic presentations. The more severe forms of the disease, acute neuronopathic GD (GD2) and chronic neuronopathic GD (GD3), also have a continuum of disease severity with an overlap in manifestations and limited genotype-phenotype correlation. In very young patients, assigning a definitive diagnosis can sometimes be challenging. Several recent studies highlight specific features of neuronopathic GD that may provide diagnostic clues. Distinguishing between the different GD types has important therapeutic implications. Currently there are limited treatment options specifically for neuronopathic GD due to the difficulty in delivering therapies across the blood-brain barrier. In this work, we present both classic and newly appreciated aspects of the Gaucher phenotype that can aid in discriminating between acute and chronic neuronopathic GD, and highlight the continuing therapeutic challenges.

Genetic characterization of the Albanian Gaucher disease patient population

Gaucher disease (GD) is a recessive metabolic disorder caused by a deficiency of the GBA gene-encoded enzyme β-glucocerebrosidase. We characterized a cohort of 36 Albanian GD patients, 31 with GD type 1 and 5 affected by GD types 2, 3, and an intermediate GD phenotype between type 2 and type 3. Of the 12 different GBA alleles that we detected, the most frequently observed was p.Asn409Ser, followed by p.[Asp448His;His294Gln]. The prevalence of the p.Leu483Pro allele was approximately 10-fold lower than reported in other populations. We identified a novel pathogenic missense variant (c.1129G>A; p.Ala377Thr). All five of our non-type 1 patients had genotypes consisting of the p.[Asp448His;His294Gln] allele in combination with another severe GBA allele. The median Lyso-Gb1 level of treated patients carrying the p.[Asp448His;His294Gln] and no p.Asn409Ser allele was significantly higher than that of treated individuals homozygous or compound heterozygous for the p.Asn409Ser allele. In conclusion, the most important distinguishing features of the Albanian GD patient population are the underrepresentation of the p.Leu483Pro allele and an unusually high number of p.[Asp448His;His294Gln] alleles originating from a common Balkan founder event. The presence of at least one p.Asn409Ser allele is associated with mild disease and low Lyso-Gb1 biomarker levels, while compound heterozygosity involving p.[Asp448His;His294Gln] and no p.Asn409Ser entails severe phenotypes and high Lyso-Gb1 levels.

Brain pathology and cerebellar purkinje cell loss in a mouse model of chronic neuronopathic Gaucher disease

Gaucher disease (GD) is currently the focus of considerable attention due primarily to the association between the gene that causes GD (GBA) and Parkinson's disease. Mouse models exist for the systemic (type 1) and for the acute neuronopathic forms (type 2) of GD. Here we report the generation of a mouse that phenotypically models chronic neuronopathic type 3 GD. Gba^-/-;Gba^tg mice, which contain a Gba transgene regulated by doxycycline, accumulate moderate levels of the offending substrate in GD, glucosylceramide, and live for up to 10 months, i.e. significantly longer than mice which model type 2 GD. Gba^-/-;Gba^tg mice display behavioral abnormalities at ∼4 months, which deteriorate with age, along with significant neuropathology including loss of Purkinje neurons. Gene expression is altered in the brain and in isolated microglia, although the changes in gene expression are less extensive than in mice modeling type 2 disease. Finally, bone deformities are consistent with the Gba^-/-;Gba^tg mice being a genuine type 3 GD model. Together, the Gba^-/-;Gba^tg mice share pathological pathways with acute neuronopathic GD mice but also display differences that might help understand the distinct disease course and progression of type 2 and 3 patients.

Symmetric, bilateral upper and lower extremity lucent lesions in a patient with Gaucher's disease on enzyme replacement therapy

We report a case of a 6-year old girl with known type 3 Gaucher's Disease on enzyme replacement therapy who developed bilateral, symmetric osteolytic lesions in her humeri and femurs. While this manifestation of Gaucher's disease has been previously documented, it is an exceedingly rare variation. We observe that this patient shares 2 commonalities with 3 other patients reported in the literature to present with this phenotype. First, the patient's L444P/L444P genotype, present in approximately 11% of all Gaucher's patients, was also seen in these other patients. Second, like the other patients, this patient was treated with enzyme replacement therapy. It is unknown whether there is a correlation between these 2 independent variables and this rare phenotype, and further investigation may be warranted.

The definition of neuronopathic Gaucher disease

Neuronopathic Gaucher disease (nGD) has a very wide clinical and genotypic spectrum. However, there is no consensus definition of nGD, including no description of how best to diagnostically separate the acute form-Gaucher type 2-from the subacute or chronic form-Gaucher type 3. In this article, we define the various forms of Gaucher disease with particular emphasis on the presence of gaze palsy in all patients with nGD. This consensus definition will help in both clinical diagnosis and appropriate patient recruitment to upcoming clinical trials.

The natural history of type 2 Gaucher disease in the 21st century: A retrospective study

OBJECTIVE

To gather natural history data to better understand the changing course of type 2 Gaucher disease (GD2) in order to guide future interventional protocols.

METHODS

A structured interview was conducted with parents of living or deceased patients with GD2. Retrospective information obtained included disease presentation, progression, medical and surgical history, medications, family history, management, complications, and cause of death, as well as the impact of disease on families.

RESULTS

Data from 23 patients were analyzed (20 deceased and 3 living), showing a mean age at death of 19.2 months, ranging from 3 to 55 months. Fourteen patients were treated with enzyme replacement therapy, 2 were treated with substrate reduction therapy, and 3 underwent bone marrow transplantation. Five patients received ambroxol and one was on N-acetylcysteine, both considered experimental treatments. Fifteen patients had gastrostomy tubes placed; 10 underwent tracheostomies. Neurologic disease manifestations included choking episodes, myoclonic jerks, autonomic dysfunction, apnea, seizures, and diminished blinking, all of which worsened as disease progressed.

CONCLUSIONS

Current available therapies appear to prolong life but do not alter neurologic manifestations. Despite aggressive therapeutic interventions, GD2 remains a progressive disorder with a devastating prognosis that may benefit from new treatment approaches.

Systemic AAV9 gene therapy using the synapsin I promoter rescues a mouse model of neuronopathic Gaucher disease but with limited cross-correction potential to astrocytes

Gaucher disease is caused by mutations in the GBA gene, which encodes for the lysosomal enzyme β-glucocerebrosidase (GCase), resulting in the accumulation of storage material in visceral organs and in some cases the brain of affected patients. While there is a commercially available treatment for the systemic manifestations, neuropathology still remains untreatable. We previously demonstrated that gene therapy represents a feasible therapeutic tool for the treatment of the neuronopathic forms of Gaucher disease (nGD). In order to further enhance the therapeutic affects to the central nervous system, we systemically delivered an adeno-associated virus (AAV) serotype 9 carrying the human GBA gene under control of a neuron-specific promoter to an nGD mouse model. Gene therapy increased the life span of treated animals, rescued the lethal neurodegeneration, normalized the locomotor behavioural defects and ameliorated the visceral pathology. Together, these results provided further indication of gene therapy as a possible effective treatment option for the neuropathic forms of Gaucher disease.

Gaucher disease: Biochemical and molecular findings in 141 patients diagnosed in Greece

Gaucher disease (GD) is characterized by a marked phenotypic and genetic diversity. It is caused by the functional deficiency of the lysosomal enzyme β-glucocerebrosidase (GCase), which in most instances results from mutations in the GBA1 gene and over 500 different disease causing mutations have been described. We present the biochemical and molecular findings in 141 GD cases (14 were siblings) with the three types of the disorder diagnosed in Greece over the last 35 years. 111/141 (78%) GD patients were of Greek origin. The remaining patients were Albanian (24/141; 17%), Syrian (2/141; 1.4%), Egyptian (2/141; 1.4%), Italian (1/141; 0.7%) and Polish (1/141; 0.7%). Mutation analysis identified 28 different mutations and 37 different genotypes. Seven of the mutations were not previously reported (T231I, D283N, N462Y, LI75P, F81L, Y135S and T482K). The most frequent mutations were N370S, D409H;H255Q and L444P. Mutation D409H;H255Q was only identified in Greek and Albanian patients. Sixteen mutations, including the novel ones, were identified only in one allele. Although the N370S mutation was identified only in type 1 patients, not all of type 1 patients carried this mutation. Our results highlight the heterogeneity of Gaucher disease and support the Balkan origin of the double mutant allele D409H;H255Q.

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Gaucher disease in Greece has an incidence estimate of 2.8/100,000 births.

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Mutation analysis in 125 patients identified 28 different mutations and 37 different genotypes.

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Seven of the mutations were not previously reported: T231I, D283N, N462Y, LI75P, F81L, Y135S and T482K.

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Mutation D409H;H255Q was only identified in Greek and Albanian patients.

White vitreous opacities in five patients with Gaucher disease type 3

Fundal abnormalities, including preretinal and retinal changes, are a rare finding in patients with the autosomal recessive lysosomal storage disorder Gaucher disease, most often described in patients with the chronic neuronopathic form (type 3). We evaluated whether these ophthalmological findings correlated with other manifestations of type 3 Gaucher disease. Reviewing the records of 40 patients with type 3 Gaucher disease, we identified five with white vitreous opacities and reviewed their clinical course in depth. Each of the patients described decreased visual acuity and "floaters" obstructing their vision. The development and/or progression of these fluffy-appearing white opacities in each patient were tracked longitudinally in the context of their neurological and other clinical findings. It was noted that all five patients shared genotype p.L483P/p.L483P (L444P/L444P) and had significant neurological, oculomotor and bone involvement and two had undergone splenectomy. Enzyme replacement therapy with recombinant glucocerebrosidase did not prevent the development or progression of these ocular opacities. Since preretinal findings, in addition to other neuro-ophthalmological findings, can be a feature of Gaucher disease, it is recommended that patients be monitored by regular eye examinations.

Variation in cognitive function over time in Gaucher disease type 3

OBJECTIVE

To identify relevant efficacy parameters essential in designing clinical trials for brain-penetrant therapies for Gaucher disease, we evaluated cognitive function longitudinally in 34 patients with Gaucher disease type 3 seen at the NIH Clinical Center.

METHODS

Individuals were tested with age-appropriate Wechsler Intelligence Scales administered between 1 and 18 times over 29 years. Variation in all IQ domains was not linear with time and was best characterized with the coefficient of variation (SD/mean) for each individual. Mixed-effects regressions were used to determine whether IQ was associated with clinical features. Models were controlled for variation in test version, participant identification, and test administrator.

RESULTS

Mean verbal, performance, and full-scale IQs were 81.77, 75.98, and 82.02, respectively, with a consistent discrepancy between verbal and performance IQs. Mean (SD) verbal, performance, and full-scale coefficient of variations were 0.07 (0.04), 0.09 (0.05), and 0.06 (0.02), respectively. IQ varied about a mean, with no clear trajectory, indicating no clear patterns of improvement or decline over time. EEG lateralization and behavioral issues were consistently associated with IQ.

CONCLUSIONS

The observed variation in IQ in Gaucher disease type 3 across the cohort and within single individuals over time may be characteristic of other neuronopathic diseases. Therefore, to reliably use IQ as an efficacy measure in any clinical trial of neurotherapeutics, a normal variation range must be established to assess the clinical relevance of any IQ change.

Five-parameter evaluation of dysphagia: A novel prognostic scale for assessing neurological decline in Gaucher disease type 2

BACKGROUND

Gaucher disease type 2 (GD2) is defined by acute neurological decline, failure to thrive, and early demise. Currently, there is no clear standard for evaluating, staging, and counseling regarding neurological decline in GD2. Due to the high prevalence of progressive dysphagia secondary to acute neurological involvement, we aimed to identify key components of swallow function which could serve as markers of disease progression in GD2.

METHODS

A post-hoc analysis of modified barium swallow studies was performed. Six parameters of swallowing were scored in a retrospective chart review of eleven infants with GD2. Mixed effects regression, principal component analysis (PCA), and a transition analysis were used to evaluate swallow function and model disease progression.

RESULTS

All patients exhibited impaired swallow function. There was no association between any of the swallow parameters and age, indicating non-linear disease progression. PCA and transition analysis identified five parameters capturing multiple dimensions of swallowing which defined two distinct disease states.

CONCLUSION

A five-parameter swallow evaluation was sufficient to identify distinct states of GD2 and model prospective outcomes. This multi-dimensional evaluation could be a useful efficacy parameter for future therapeutic trials in GD2 and other neurodegenerative disorders of infancy.

Modeling neuronopathic storage diseases with patient-derived culture systems

Lysosomes are organelles involved in the degradation and recycling of macromolecules, and play a critical role in sensing metabolic information in the cell. A class of rare metabolic diseases called lysosomal storage disorders (LSD) are characterized by lysosomal dysfunction and the accumulation of macromolecular substrates. The central nervous system appears to be particularly vulnerable to lysosomal dysfunction, since many LSDs are characterized by severe, widespread neurodegeneration with pediatric onset. Furthermore, variants in lysosomal genes are strongly associated with some common neurodegenerative disorders such as Parkinson's disease (PD). To better understand disease pathology and develop novel treatment strategies, it is critical to study the fundamental molecular disease mechanisms in the affected cell types that harbor endogenously expressed mutations. The discovery of methods for reprogramming of patient-derived somatic cells into induced pluripotent stem cells (iPSCs), and their differentiation into distinct neuronal and glial cell types, have provided novel opportunities to study mechanisms of lysosomal dysfunction within the relevant, vulnerable cell types. These models also expand our ability to develop and test novel therapeutic targets. We discuss recently developed methods for iPSC differentiation into distinct neuronal and glial cell types, while addressing the need for meticulous experimental techniques and parameters that are essential to accurately identify inherent cellular pathologies. iPSC models for neuronopathic LSDs and their relationship to sporadic age-related neurodegeneration are also discussed. These models should facilitate the discovery and development of personalized therapies in the future.

Gene expression profile in patients with Gaucher disease indicates activation of inflammatory processes

Gaucher disease (GD) is a rare inherited metabolic disease caused by pathogenic variants in the GBA1 gene. So far, the pathomechanism of GD was investigated mainly in animal models. In order to delineate the molecular changes in GD cells we analysed gene expression profile in cultured skin fibroblasts from GD patients, control individuals and, additionally, patients with Niemann-Pick type C disease (NPC). We used expression microarrays with subsequent validation by qRT-PCR method. In the comparison GD patients vs. controls, the most pronounced relative fold change (rFC) in expression was observed for genes IL13RA2 and IFI6 (up-regulated) and ATOH8 and CRISPLD2 (down-regulated). Products of up-regulated and down-regulated genes were both enriched in genes associated with immune response. In addition, products of down-regulated genes were associated with cell-to-cell and cell-to-matrix interactions, matrix remodelling, PI3K-Akt signalling pathway and a neuronal survival pathway. Up-regulation of PLAU, IFIT1, TMEM158 and down-regulation of ATOH8 and ISLR distinguished GD patients from both NPC patients and healthy controls. Our results emphasize the inflammatory character of changes occurring in human GD cells indicating that further studies on novel therapeutics for GD should consider anti-inflammatory agents.

First Clinicogenetic Description of Parkinson's Disease Related to GBA Mutation S107L

Background

Mutations in the glucocerebrosidase gene (GBA) are a common genetic risk factor for Parkinson's disease (PD). Mutations in the N-terminus part of GBA are less commonly found in association with PD than those in the C-terminus. Phenotypic characterization of GBA-related PD has been challenging, in part attributed to differential impact of distinct GBA mutations.

Aim

To provide a phenotypic description of two patients with PD heterozygous for the GBA mutation S107L. The S107L mutation is located in the catalytic domain of glucocerebrosidase and has not previously been reported in patients with PD.

Methods

Motor and nonmotor symptoms (NMS) of PD were evaluated using established rating scales and questionnaires. The genotype was determined by Sanger sequencing.

Results

Two half-brothers, both heterozygous carriers of S107L, exhibited an early PD onset with several NMS.

Conclusions

In these patients, heterozygosity for S107L was associated with an early onset of PD with NMS.

Bone manifestations in neuronopathic Gaucher disease while receiving high-dose enzyme replacement therapy

Avascular necrosis (AVN), one type of bone infarction, is a major irreversible complication of Gaucher disease (GD). In this report, two pediatric patients with GD type 3, homozygous for the L483P pathogenic variant (formerly L444P), developed AVN despite treatment on long-term, high-dose enzyme replacement therapy (ERT). ERT was initiated in both patients, who had intact spleens, shortly after diagnosis with an initial dramatic response. However, both patients exhibited AVN after 5.5 and 11 years on high-dose ERT, respectively, despite good compliance and normalized hematological findings and visceral symptoms. This report demonstrates the importance of careful, regular surveillance of the musculoskeletal system in addition to monitoring the neurological symptoms associated with neuronopathic GD. Additionally, it highlights the limitations of ERT in terms of targeting certain sanctuary sites such as bone marrow and suggests the need for new treatment modalities other than ERT monotherapy to address these limitations.

Ophthalmic manifestations of Gaucher disease: the most common lysosomal storage disorder

Gaucher disease (GD) results from a deficiency of glucocerebrosidase activity and the subsequent accumulation of the enzyme's metabolites, principally glucosylsphingosine and glucosylceramide. There are three principal forms: Type I, which is the most common, is usually considered non-neuronopathic. Type II, III and IIIc manifest earlier and have neurological sequelae due to markedly reduced enzyme activity. Gaucher's can be associated with ophthalmological sequelae but these have not been systematically reviewed. We therefore performed a comprehensive literature review of all such ophthalmic abnormalities associated with the different types of Gaucher disease. We systematically searched the literature (1950 - present) for functional and structural ocular abnormalities arising in patients with Gaucher disease and found that all subtypes can be associated with ophthalmic abnormalities; these range from recently described intraocular lesions to disease involving the adnexae, peripheral nerves and brain. In summary, Gaucher can affect most parts of the eye. Rarely is it sight-threatening; some but not all manifestations are amenable to treatment, including with enzyme replacement and substrate reduction therapy. Retinal involvement is rare but patients with ocular manifestations should be monitored and treated early to reduce the risk of progression and further complications. As Gaucher disease is also associated with Parkinsons disease and may also confer an increased risk of malignancy (particularly haematological forms and melanoma), any ocular abnormalities should be fully investigated to exclude these potential underlying conditions.

Neurological effects of glucocerebrosidase gene mutations

The association between Gaucher disease (GD) and Parkinson disease (PD) has been described for almost two decades. In the biallelic state (homozygous or compound heterozygous) mutations in the glucocerebrosidase gene (GBA) may cause GD, in which glucosylceramide, the sphingolipid substrate of the glucocerebrosidase enzyme (GCase), accumulates in visceral organs leading to a number of clinical phenotypes. In the biallelic or heterozygous state, GBA mutations increase the risk for PD. Mutations of the GBA allele are the most significant genetic risk factor for idiopathic PD, found in 5%–20% of idiopathic PD cases depending on ethnicity. The neurological consequences of GBA mutations are reviewed and the proposition that GBA mutations result in a disparate but connected range of clinically and pathologically related neurological features is discussed. The literature relating to the clinical, biochemical and genetic basis of GBA PD, type 1 GD and neuronopathic GD is considered highlighting commonalities and distinctions between them. The evidence for a unifying disease mechanism is considered.

Progressive myoclonus epilepsy in Gaucher Disease due to a new Gly-Gly mutation causing loss of an Exonic Splicing Enhancer

BACKGROUND

Patients with Gaucher Disease (GD) exhibit three phenotypes, including type 1 (non-neuronopathic), type 2 (acute neuronopathic), and type 3 (subacute neuronopathic).

AIM

Identifying which GBA changes represent benign polymorphisms and which may result in disease-causing mutations is essential for diagnosis and genotype/phenotype correlations but is often challenging.

RESULTS

Here, we describe a patient with type 3 GD, presenting with drug-resistant epilepsy, who bears a set of GBA polymorphic variants including the novel c.363A > G (Gly82Gly) synonymous mutation. In silico predictions, mRNA and functional studies revealed that the new Gly82Gly mutation causes skipping of GBA exon 4, leading to a severe reduction of the wild type GBA mRNA. This is the first report of a synonymous change causing GD through loss of an exonic splicing enhancer sequence. The synonymous mutation is in trans with the Asn188Ser missense mutation, thus making the Asn188Ser responsible for the patient's phenotype and strengthening the association of Asn188Ser with the particular neurological phenotype of type 3 GD.

CONCLUSION

We strengthen the association of Asn188Ser with the type 3 GD phenotype and progressive myoclonus epilepsy. Our data confirm that in silico predictions and mRNA analysis are mandatory in discriminating pathological mutations from the background of harmless polymorphisms, especially synonymous changes.

CE: Understanding the Nurse's Role in Managing Gaucher Disease

: Lysosomal storage disorders (LSDs) are a group of inherited metabolic conditions, the overall incidence of which is estimated to range from one in 5,000 to one in 7,000 live births. Gaucher disease, the most common LSD, is of autosomal recessive inheritance. It results from a deficiency of acid β-glucocerebrosidase and can affect the spleen, liver, bone, bone marrow, and central nervous system. Gaucher disease is clinically classified into one of three phenotypes, depending on the absence or presence of neurodegenerative disease and the rate of disease progression. Although there is no cure for Gaucher disease, it may be treated with enzyme replacement and substrate reduction therapy. With the development of enzyme testing through dried blood spots, Gaucher disease may now be detected at birth through newborn screening. The purpose of this article is to review the epidemiology and pathophysiology of Gaucher disease, update nurses on advances in newborn screening, diagnosis, and management of this genetic disorder, and highlight the role of nurses in the diagnosis and care of patients with Gaucher disease.

Recent advances in the diagnosis and management of Gaucher disease

INTRODUCTION

Gaucher disease, the autosomal recessive deficiency of the lysosomal enzyme glucocerebrosidase, is associated with wide phenotypic diversity including non-neuronopathic, acute neuronopathic, and chronic neuronopathic forms. Overlap between types can render definitive diagnoses difficult. However, differentiating between the different phenotypes is essential due to the vast differences in clinical outcomes and response to therapy. Genotypic information is helpful, but cannot always be used to make clinical predictions. Current treatments for Gaucher disease, including enzyme replacement therapy and substrate reduction therapy, can reverse many of the non-neurological manifestations, but these therapies must be administered continually and are extremely costly.

AREAS COVERED

We reviewed the literature concerning the varied clinical presentations of Gaucher disease throughout the lifetime, along with treatment options, management goals, and current and future research challenges. A PubMed literature search was performed for relevant publications between 1991 to January 2018.

EXPERT COMMENTARY

Interest and research in the field of Gaucher disease is rapidly expanding. However, significant barriers remain in our ability to predict phenotype, assess disease progression using objective biomarkers, and determine optimal treatment strategy on an individual basis. As the field grows, we anticipate identification of genetic modifiers, new biomarkers, and small-molecule chaperone therapies, which may improve patient quality of life.

Characteristics of 26 patients with type 3 Gaucher disease: A descriptive analysis from the Gaucher Outcome Survey

The Gaucher Outcome Survey (GOS) is an international disease-specific registry established in 2010 for patients with a confirmed diagnosis of Gaucher disease (GD), regardless of GD type or treatment status. Historically, there has been a limited understanding of type 3 GD (GD3) and its natural history in patients irrespective of their treatment status. Here, we describe the disease characteristics of patients with GD3 enrolled in GOS. As of October 2015, 1002 patients had been enrolled, 26 of whom were reported as GD3. The majority of patients with GD3 were from the US (13; 50.0%), seven (26.9%) were from the UK, three (11.5%) from Israel, and three (11.5%) from Brazil. No patients were of Ashkenazi Jewish origin. Median age of symptom onset was 1.4 (interquartile range: 0.5–2.0) years. The most common GBA1 mutation genotype was L444P/L444P, occurring in 16 (69.6%) of 23 patients who had genotyping information available. Nine patients reported a family history of GD (any type). Of 21 patients with treatment status information, 20 (95.2%) had received GD-specific treatment at any time, primarily imiglucerase (14 patients) and/or velaglucerase alfa (13 patients). Hemoglobin concentrations and platelet counts at GOS entry were within normal ranges for most patients, and there were no reports of severe hepatomegaly or of splenomegaly in non-splenectomized patients, most likely indicative of the effects of treatment received prior to GOS entry. This analysis provides information on the characteristics of patients with GD3 that could be used as the baseline for longitudinal follow-up of these patients.

Exploring the patient journey to diagnosis of Gaucher disease from the perspective of 212 patients with Gaucher disease and 16 Gaucher expert physicians

Gaucher disease (GD) is a rare hereditary disorder caused by a deficiency of the lysosomal enzyme β-glucocerebrosidase. Diagnosis is challenging owing to a wide variability in clinical manifestations and severity of symptoms. Many patients may experience marked delays in obtaining a definitive diagnosis. The two surveys reported herein aimed to explore the patient journey to diagnosis of GD from the perspectives of Gaucher expert physicians and patients. Findings from the surveys revealed that many patients experienced diagnostic delays and misdiagnoses, with nearly 1 in 6 patients stating that they were not diagnosed with GD for 7years or more after first consulting a doctor. Physicians and patients both reported multiple referrals to different specialties before a diagnosis of GD was obtained, with primary care, haematology/haematology-oncology and paediatrics the main specialties to which patients first presented. Splenomegaly, thrombocytopenia, anaemia and bone pain were reported as the most common medical problems at first presentation in both surveys. These findings support a clear need for straightforward and easy-to-follow guidance designed to assist non-specialists to identify earlier patients who are at risk of GD.

Diagnosis features of pediatric Gaucher disease patients in the era of enzymatic therapy, a national-base study from the Spanish Registry of Gaucher Disease

BACKGROUND

The enzymatic replacement therapy (ERT) availability for Gaucher disease (GD) has changed the landscape of the disease, several countries have screening programs. These actions have promoted the early diagnosis and avoided many complications in pediatric patients. In Spain ERT has been available since 1993 and 386 patients have been included in the Spanish Registry of Gaucher Disease (SpRGD). The aim of this study is to analyze the impact of ERT on the characteristics at time of diagnosis and initial complications in pediatric Gaucher disease patients.

AIM

To analyze the impact of ERT on the characteristics at time of diagnosis and initial complications in pediatric Gaucher disease patients.

METHODS

A review of data in SpRGD from patients' diagnosed before 18 years old was performed. The cohort was split according the year of diagnosis (≤1994, cohort A; ≥1995, cohort B).

RESULTS

A total of 98 pediatric patients were included, GD1: 80, GD3: 18; mean age: 7.2 (0.17-16.5) years, 58 (59.2%) males and 40 (40.8%) females. Forty-five were diagnosed ≤ 1994 and 53 ≥ 1995. Genotype: N370S/N370S: 2 (2.0%), N370S/L444P: 27 (27.5%), N370S/other: 47 (48%), L444P/L444P: 7 (7.1%), L444P/D409H: 2 (2.0%), L444P/other: 3 (6.2%), other/other: 10 (10.2%). The mean age at diagnosis was earlier in patients diagnosed after 1995 (p < 0.001) and different between the subtypes, GD1: 8.2 (0.2-16.5) years and GD3: 2.8 (0.17-10.2) years (p < 0.001). There were more severe patients in the group diagnosed before 1994 (p = 0.045) carrying L444P (2), D409H (2), G377S (1), G195W (1) or the recombinant mutation. The patients' diagnosed ≤1994 showed worse cytopenias, higher chance of bone vascular complications at diagnosis and previous spleen removal. The patients started ERT at a median time after diagnosis of 5.2 years [cohort A] and 1.6 years [cohort B] (p < 0.001).

CONCLUSIONS

The early diagnosis of Gaucher disease in the era of ERT availability has permitted to reduce the incidence of severe and irreversible initial complication in pediatric patients, and this has permitted better development of these patients. This is the largest pediatric cohort from a national registry.

Induced Pluripotent Stem Cell Modeling of Gaucher's Disease: What Have We Learned?

Gaucher’s disease (GD) is the most frequently inherited lysosomal storage disease, presenting both visceral and neurologic symptoms. Mutations in acid β-glucocerebrosidase disrupt the sphingolipid catabolic pathway promoting glucosylceramide (GlcCer) accumulation in lysosomes. Current treatment options are enzyme replacement therapy (ERT) and substrate reduction therapy (SRT). However, neither of these approaches is effective in treating the neurological aspect of the disease. The use of small pharmacological compounds that act as molecular chaperones is a promising approach that is still experimental. In recent years, an association between GD and Parkinson like synucleinopathies has been discovered. Since 1992, a number of mouse models of GD have been the developed and partially reproduce phenotype of the disease. More recently, the discovery of direct reprograming has allowed the derivation of induced pluripotent stem cells (iPSc) from fibroblasts obtained from GD patients. iPSc can be expanded indefinitely in vitro and differentiated to macrophages and neurons, the main relevant cell types involved in GD. In this work, we review iPSc models of GD and summarize what we have learned from this system.