The clinical management of Type 2 Gaucher disease

Molecular mechanisms of the ambroxol action in Gaucher disease and GBA1 mutation-associated Parkinson disease

Glucocerebrosidase (GCase), encoded by the GBA1 gene, is one of the lysosomal enzymes responsible for hydrolyzing the glycosphingolipids. Deficiency in GCase activity (in patients with two defective alleles of GBA1) leads to glucosylceramide storage in lysosomes which in turn results in the development of the Gaucher diseases, a lysosomal storage disorder, while a heterozygous state may be correlated with the GBA1 mutation-associated Parkinson disease. One of the proposed forms of therapy for these two conditions is the use of pharmacological chaperones which work by facilitating the achievement of the correct conformation of abnormally folded enzymes. Several compounds with chaperone activities against GCase have already been tested, one of which turned out to be ambroxol. Studies conducted on the action of this compound have indeed indicated its effectiveness in increasing GCase levels and activity. However, some data have begun to question its activity as a chaperone against certain GCase variants. Then, a number of articles appeared pointing to other mechanisms of action of ambroxol, which may also contribute to the improvement of patients' condition. This paper summarizes the biological mechanisms of action of ambroxol in Gaucher disease and GBA1 mutation-associated Parkinson disease, focused on its activity as a chaperone, modulator of ERAD pathways, inducer of autophagy, and pain reliever in cellular and animal models as well as in patients. The effects of these activities on the reduction of disease markers and symptoms in patients are also discussed. Consideration of all the properties of ambroxol can help in the appropriate choice of therapy and the determination of the effective drug dose.

Cost-effectiveness of ambroxol in the treatment of Gaucher disease type 2

Objective

Our aim was to compare the costs and efficacy of ambroxol in combination with imiglucerase with the costs and efficacy of imiglucerase only in the treatment of Gaucher disease type 2 (GD2) in the socio-economic settings of the Republic of Serbia, an upper-middle-income European economy.

Methods

The perspective of the Serbian Republic Health Insurance Fund was chosen for this study, and the time horizon was 6 years. The main outcomes of the study were quality-adjusted life years gained with ambroxol + imiglucerase and comparator, and direct costs of treatment. The study was conducted through the generation and simulation of the Markov chain model. The model results were obtained after Monte Carlo microsimulation of a sample with 1,000 virtual patients.

Results

Treatment with ambroxol in combination with imiglucerase was cost-effective when compared with imiglucerase only and was associated with positive values of net monetary benefit regardless of the onset of the disease. Such beneficial result for ambroxol and imiglucerase combination is primarily driven by the low cost of ambroxol and its considerable clinical effectiveness in slowing the progression of neural complications of GD2.

Conclusion

If ambroxol and imiglucerase are used in combination for the treatment of GD2, it is more cost-effective than using imiglucerase alone.

Neuronopathic Gaucher disease: Rare in the West, common in the East

Gaucher disease (GD) stands as one of the most prevalent lysosomal disorders, yet neuronopathic GD (nGD) is an uncommon subset characterized by a wide array of clinical manifestations that complicate diagnosis, particularly when neurological symptoms are understated. nGD may manifest as the acute neuronopathic type, or GD type 2 (GD2), either prenatally or within the first weeks to months of life, whereas GD type 3 (GD3) symptoms may emerge at any point during childhood or occasionally in adolescence. The clinical presentation encompasses severe systemic involvement to mild visceral disease, often coupled with a spectrum of progressive neurological signs and symptoms such as cognitive impairment, ataxia, seizures, myoclonus, varying degrees of brainstem dysfunction presenting with stridor, apneic episodes, and/or impaired swallowing. This manuscript aims to provide a comprehensive review of the incidence, distinctive presentations, and diverse clinical phenotypes of nGD across various countries and regions. It will explore the natural history of the neurodegenerative process in GD, shedding light on its various manifestations during infancy and childhood, and offer insights into the diagnostic journey, the challenges faced in the clinical management, and current and investigative therapeutic approaches for GD's neurological variants.

Gaucher's Disease in an Adult Male: A Case Report of a Rare Mutation

Gaucher's disease is a rare autosomal recessive inborn error of metabolism. As the presentation of this disease is similar to more common diseases like malaria, portal hypertension, hematological disorders, and kala-azar, this rare disease may not be thought of as a differential diagnosis, and a high index of suspicion is required to avoid diagnostic delay. We report a case of type 1 Gaucher's disease in an adult male born out of a consanguineous marriage. He was from a region where the prevalence of infectious diseases and sickle cell anemia is high. He presented with abdominal distension, hepatosplenomegaly, and pancytopenia. Bone marrow biopsy showed the presence of Gaucher cells. Glucocerebrosidase levels showed decreased enzyme activity. The genetic study revealed a very rare mutation that has not been reported in the 1000 Genomes database till now. Retrospectively, the most important clue was his birth out of a consanguineous marriage of his parents.

A review on Gaucher disease: therapeutic potential of β-glucocerebrosidase-targeted mRNA/saRNA approach

Gaucher disease (GD), a rare hereditary lysosomal storage disorder, occurs due to a deficiency in the enzyme β-glucocerebrosidase (GCase). This deficiency leads to the buildup of substrate glucosylceramide (GlcCer) in macrophages, eventually resulting in various complications. Among its three types, GD2 is particularly severe with neurological involvements. Current treatments, such as enzyme replacement therapy (ERT), are not effective for GD2 and GD3 due to their inability to cross the blood-brain barrier (BBB). Other treatment approaches, such as gene or chaperone therapies are still in experimental stages. Additionally, GD treatments are costly and can have certain side effects. The successful use of messenger RNA (mRNA)-based vaccines for COVID-19 in 2020 has sparked interest in nucleic acid-based therapies. Remarkably, mRNA technology also offers a novel approach for protein replacement purposes. Additionally, self-amplifying RNA (saRNA) technology shows promise, potentially producing more protein at lower doses. This review aims to explore the potential of a cost-effective mRNA/saRNA-based approach for GD therapy. The use of GCase-mRNA/saRNA as a protein replacement therapy could offer a new and promising direction for improving the quality of life and extending the lifespan of individuals with GD.

Lysosomal Dysfunction: Connecting the Dots in the Landscape of Human Diseases

Lysosomes are the main organelles responsible for the degradation of macromolecules in eukaryotic cells. Beyond their fundamental role in degradation, lysosomes are involved in different physiological processes such as autophagy, nutrient sensing, and intracellular signaling. In some circumstances, lysosomal abnormalities underlie several human pathologies with different etiologies known as known as lysosomal storage disorders (LSDs). These disorders can result from deficiencies in primary lysosomal enzymes, dysfunction of lysosomal enzyme activators, alterations in modifiers that impact lysosomal function, or changes in membrane-associated proteins, among other factors. The clinical phenotype observed in affected patients hinges on the type and location of the accumulating substrate, influenced by genetic mutations and residual enzyme activity. In this context, the scientific community is dedicated to exploring potential therapeutic approaches, striving not only to extend lifespan but also to enhance the overall quality of life for individuals afflicted with LSDs. This review provides insights into lysosomal dysfunction from a molecular perspective, particularly in the context of human diseases, and highlights recent advancements and breakthroughs in this field.

A rare disease in adult women: Gaucher disease

Gaucher disease is a rare, autosomal recessive disorder caused by inborn errors of metabolism. Globally, more than 27 million people are born each year, and approximately 19,000 neonates are born with lysosomal storage disease. We report a rare case of Gaucher disease in an adult female patient of non-consanguineous parents in a subtropical area of Jiangxi Province, China. This area has a high prevalence of schistosomiasis. The diagnosis of this case posed a great challenge because of the possible differential diagnoses of pancytopenia with hepatomegaly and giant splenomegaly. The key component of the patient's diagnosis was her medical history in which it was documented that her brother had died of hepatocellular carcinoma of unknown origin. We diagnosed the patient through a combination of a pathological biopsy and imaging plus the patient's medical history.

Changing clinical manifestations of Gaucher disease in Taiwan

BACKGROUND

Gaucher 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 METHODS

Data 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.

RESULTS

Our 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.

CONCLUSION

ERT 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.

Interaction with ERp57 is required for progranulin protection against Type 2 Gaucher disease

Gaucher disease (GD), one of the most common lysosomal storage diseases, is caused by GBA1 mutations resulting in defective glucocerebrosidase (GCase) and consequent accumulation of its substrates β-glucosylceramide (β-GlcCer). We reported progranulin (PGRN), a secretary growth factor-like molecule and an intracellular lysosomal protein was a crucial co-factor of GCase. PGRN binds to GCase and recruits Heat Shock Protein 70 (Hsp70) to GCase through its C-terminal Granulin (Grn) E domain, termed as ND7. In addition, both PGRN and ND7 are therapeutic against GD. Herein we found that both PGRN and its derived ND7 still displayed significant protective effects against GD in Hsp70 deficient cells. To delineate the molecular mechanisms underlying PGRN's Hsp70-independent regulation of GD, we performed a biochemical co-purification and mass spectrometry with His-tagged PGRN and His-tagged ND7 in Hsp70 deficient cells, which led to the identification of ERp57, also referred to as protein disulfide isomerase A3 (PDIA3), as a protein that binds to both PGRN and ND7. Within type 2 neuropathic GD patient fibroblasts L444P, bearing GBA1 L444P mutation, deletion of ERp57 largely abolished the therapeutic effects of PGRN and ND7, as manifested by loss of effects on lysosomal storage, GCase activity, and β-GlcCer accumulation. Additionally, recombinant ERp57 effectively restored the therapeutic effects of PGRN and ND7 in ERp57 knockout L444P fibroblasts. Collectively, this study reports ERp57 as a previously unrecognized binding partner of PGRN that contributes to PGRN regulation of GD.

Targeting neuronal lysosomal dysfunction caused by β-glucocerebrosidase deficiency with an enzyme-based brain shuttle construct

Mutations in glucocerebrosidase cause the lysosomal storage disorder Gaucher's disease and are the most common risk factor for Parkinson's disease. Therapies to restore the enzyme's function in the brain hold great promise for treating the neurological implications. Thus, we developed blood-brain barrier penetrant therapeutic molecules by fusing transferrin receptor-binding moieties to β-glucocerebrosidase (referred to as GCase-BS). We demonstrate that these fusion proteins show significantly increased uptake and lysosomal efficiency compared to the enzyme alone. In a cellular disease model, GCase-BS rapidly rescues the lysosomal proteome and lipid accumulations beyond known substrates. In a mouse disease model, intravenous injection of GCase-BS leads to a sustained reduction of glucosylsphingosine and can lower neurofilament-light chain plasma levels. Collectively, these findings demonstrate the potential of GCase-BS for treating GBA1-associated lysosomal dysfunction, provide insight into candidate biomarkers, and may ultimately open a promising treatment paradigm for lysosomal storage diseases extending beyond the central nervous system.

Facial features of lysosomal storage disorders

INTRODUCTION

The use of facial recognition technology has diversified the diagnostic toolbelt for clinicians and researchers for the accurate diagnoses of patients with rare and challenging disorders. Specific identifiers in patient images can be grouped using artificial intelligence to allow the recognition of diseases and syndromes with similar features. Lysosomal storage disorders are rare, and some have prominent and unique features that may be used to train the accuracy of facial recognition software algorithms. Noteworthy features of lysosomal storage disorders (LSDs) include facial features such as prominent brows, wide noses, thickened lips, mouth, and chin, resulting in coarse and rounded facial features.

AREAS COVERED

We evaluated and report the prevalence of facial phenotypes in patients with different LSDs, noting two current examples when artificial intelligence strategies have been utilized to identify distinctive facies.

EXPERT OPINION

Specific LSDs, including Gaucher disease, Mucolipidosis IV and Fabry disease have recently been distinguished using facial recognition software. Additional lysosomal disorders LSDs lysosomal storage disorders with unique and distinguishable facial features also merit evaluation using this technology. These tools may ultimately aid in the identification of specific LSDs and shorten the diagnostic odyssey for patients with these rare and under-recognized disorders.

A systematic review of economic evaluations of enzyme replacement therapy in Lysosomal storage diseases

Objective

The objective of this paper is to assess the economic profile of enzyme replacement therapy (ERT) to symptomatic patients with Pompe, Fabry, Gaucher disease and Lysosomal acid lipase (LAL) deficiency.

Methods

A systematic search was performed to retrieve and critically assess economic evaluations of enzyme replacement therapy. Publications were screened according to predefined criteria and evaluated according to the Quality of Economic Studies. Data were narratively synthesized.

Results

The Incremental Cost-Effectiveness Ratio greatly exceeded willingness to pay thresholds. The cost of the medication dominated the sensitivity analysis. For Infantile-onset Pompe’s disease, the incremental cost-effectiveness ratio (ICER) was estimated at €1.043.868 per Quality-adjusted life year (QALY) based on the dose of alglucosidase 40 mg/kg/ week, and €286.114 per QALY for 20 mg of alglucosidase/kg/2 weeks. For adults patients presenting with Pompe disease the reported was ICER € 1.8 million/ QALY. In the case of Fabry disease, the ICER per QALY amounts to 6.1 million Euros/QALY. Respectively for Gaucher’s disease, the ICER /QALY was estimated at € 884,994 per QALY. Finally, for patients presenting LAL deficiency NCPE perpetuated an ICER of €2,701,000/QALY.

Discussion

ERT comprise a promising treatment modality for orphan diseases; nevertheless, it is interlaced with a substantial economic burden. Moreover, the available data on the cost-effectiveness ratio are scarce. For certain diseases, such as Fabry, a thorough selection of patients could exert a beneficial effect on the reported ICER. Steep price reductions are imperative for these products, in the conventional reimbursement pathway or a new assessment framework should be elaborated, which in principle, should target uncertainty.

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.

Qualitative analysis of patient interviews on the burden of neuronopathic Gaucher disease in Japan

BACKGROUND

Gaucher disease (GD) is a rare, autosomal recessive lysosomal storage disorder that adversely affects life expectancy and health-related quality of life (HRQOL). Although HRQOL questionnaires are available for type 1 GD, they are not suitable for patients with the neuronopathic types 2 and 3 GD who have neurological symptoms that develop during early childhood or adolescence. Here we report the development of a language-validated HRQOL questionnaire specifically for patients with neuronopathic types 2 and 3 GD in Japan, which is the first step toward HRQOL questionnaire provision for all types of GD in the future.

METHODS

In February and March 2021, semi-structured interviews were conducted by the authors (supported by qualified interviewers) with patients and/or their caregivers (for patients < 16 years old) who were recruited from a Japanese patient association, the Association of Gaucher Disease Patients in Japan. Qualitative analysis of interview transcripts was used to identify major themes and key topics within those themes. Hierarchical cluster analysis and co-occurrence network analysis were performed to map relationships between commonly occurring words. The study is registered at the UMIN Clinical Trials Registry ( https://www.umin.ac.jp/ctr/index.htm [UMIN000042872]).

RESULTS

Three main themes emerged from qualitative analysis: treatment status, patient burden, and social support systems. Key topics within each theme included hearing impairment, visual impairment, difficulty swallowing, difficulty speaking, involuntary movement of extremities, epileptic seizures, and body aches (treatment status); anxiety about symptoms, difficulty with exercise and work, anxiety about continuing treatment, anxiety about going out, and tiredness from hospital visit or treatment (patient burden); and dissatisfaction about government service, lack of social support, and information exchange in the patient association (social support systems). Commonly used words and the relationships between words identified through the hierarchical cluster and co-occurrence network analyses supported these themes and topics.

CONCLUSIONS

The themes and topics identified in this analysis were specific to patients with types 2 and 3 GD and will be used to inform the development of a HRQOL questionnaire specifically for patients with all GD types.

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.

Newborn screening for Gaucher disease in Japan

Gaucher disease (GD) is an autosomal recessive inborn metabolic disorder caused by a glucocerebrosidase (GCase) defect. GD is classified into three main types depending on accompanying neurological symptoms. Enzyme replacement therapy and substrate reduction therapy are limited in the treatment of neurological symptoms, and using genotype and GCase activity to discriminate between non-neuronopathic and neuronopathic GD may be challenging as the two sometimes phenotypically overlap. The number of patients exhibiting neurological symptoms in Japan is significantly higher than that in Europe and the United States, and newborn screening (NBS) is still not actively performed in Japan. Definitive determination of the actual frequency and proportion of the type of GD from the results of NBS remains inconclusive. We performed NBS for Fabry disease, Pompe disease, and GD, mainly in the Kyushu area in Japan. Herein, we discuss the results of NBS for GD, as well as, the insights gained from following the clinical course of patients diagnosed through NBS. A total of 155,442 newborns were screened using an enzyme activity assay using dried blood spots. We found four newborns showing lower GCase activity and were definitively diagnosed with GD by GBA gene analysis. The frequency of GD diagnosis through NBS was 1 in 77,720 when limited to the probands. This frequency is higher than that previously estimated in Japan. In the future, NBS for GD is expected to be performed in many regions of Japan and contribute to detecting more patients with GD. Early screening and diagnosis may have a very significant impact on the quality of life and potentially longevity in infants with GD.

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Newborn screening (NBS) identified 4 cases of Gaucher disease (GD) with few false positives in Japan.

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The frequency of GD diagnosis through NBS was 1 in 77,720, being higher than the previously estimated.

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Early diagnosis may have a very significant impact on the quality of life and potentially longevity in infants with GD.

The diagnosis and management of Gaucher disease in pediatric patients: Where do we go from here?

Gaucher disease (GD) is an autosomal recessive inherited lysosomal storage disease that often presents in early childhood and is associated with damage to multiple organ systems. Many challenges associated with GD diagnosis and management arise from the considerable heterogeneity of disease presentations and natural history. Phenotypic classification has traditionally been based on the absence (in type 1 GD) or presence (in types 2 and 3 GD) of neurological involvement of varying severity. However, patient management and prediction of prognosis may be best served by a dynamic, evolving definition of individual phenotype rather than by a rigid system of classification. Patients may experience considerable delays in diagnosis, which can potentially be reduced by effective screening programs; however, program implementation can involve ethical and practical challenges. Variation in the clinical course of GD and an uncertain prognosis also complicate decisions concerning treatment initiation, with differing stakeholder perspectives around efficacy and acceptable cost/benefit ratio. We review the challenges faced by physicians in the diagnosis and management of GD in pediatric patients. We also consider future directions and goals, including acceleration of accurate diagnosis, improvements in the understanding of disease heterogeneity (natural history, response to treatment, and prognosis), the need for new treatments to address unmet needs for all forms of GD, and refinement of the tools for monitoring disease progression and treatment efficacy, such as specific biomarkers.

A rare cause of hydrops fetalis in two Gaucher disease type 2 patients with a novel mutation

Gaucher disease type 2 is the most progressive and the rarest form of Gaucher disease, defined as the acute neuronopathic type. We presented two GD2 patients who died before three months of age due to severe septicemia, respiratory and liver failure. One was homozygous for a novel GBA variant c.590 T > A (p.197 K), and the second homozygous for the known GBA mutation c.1505G > A (p.R502H). Ichthyosis, hydrops fetalis, apnea, myoclonic seizures, and hepatosplenomegaly occurred in both patients, but hypertrophic cardiomyopathy was observed only in the second and unilateral cataract in the first patient. Due to the disease's early and rapid neurological progression, we did not administer ERT to our patients. It is strongly believed that early diagnosis is essential, and prenatal diagnosis makes genetic counselling possible for future pregnancies.

Glucocerebrosidase Mutations Cause Mitochondrial and Lysosomal Dysfunction in Parkinson’s Disease: Pathogenesis and Therapeutic Implications

Parkinson’s disease (PD) is the second most common neurodegenerative disease and is characterized by multiple motor and non-motor symptoms. Mutations in the glucocerebrosidase (GBA) gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase), which hydrolyzes glucosylceramide (GlcCer) to glucose and ceramide, are the most important and common genetic PD risk factors discovered to date. Homozygous GBA mutations result in the most common lysosomal storage disorder, Gaucher’s disease (GD), which is classified according to the presence (neuronopathic types, type 2 and 3 GD) or absence (non-neuronopathic type, type 1 GD) of neurological symptoms. The clinical manifestations of PD in patients with GBA mutations are indistinguishable from those of sporadic PD at the individual level. However, accumulating data have indicated that GBA-associated PD patients exhibit a younger age of onset and a greater risk for cognitive impairment and psychiatric symptoms. The mechanisms underlying the increased risk of developing PD in GBA mutant carriers are currently unclear. Contributors to GBA-PD pathogenesis may include mitochondrial dysfunction, autophagy-lysosomal dysfunction, altered lipid homeostasis and enhanced α-synuclein aggregation. Therapeutic strategies for PD and GD targeting mutant GCase mainly include enzyme replacement, substrate reduction, gene and pharmacological small-molecule chaperones. Emerging clinical, genetic and pathogenic studies on GBA mutations and PD are making significant contributions to our understanding of PD-associated pathogenetic pathways, and further elucidating the interactions between GCase activity and neurodegeneration may improve therapeutic approaches for slowing PD progression.

Discovery of Brain-Penetrant Glucosylceramide Synthase Inhibitors with a Novel Pharmacophore

Inhibition of glucosylceramide synthase (GCS) is a major therapeutic strategy for Gaucher's disease and has been suggested as a potential target for treating Parkinson's disease. Herein, we report the discovery of novel brain-penetrant GCS inhibitors. Assessment of the structure-activity relationship revealed a unique pharmacophore in this series. The lipophilic ortho-substituent of aromatic ring A and the appropriate directionality of aromatic ring B were key for potency. Optimization of the absorption, distribution, metabolism, elimination, toxicity (ADMETox) profile resulted in the discovery of T-036, a potent GCS inhibitor in vivo. Pharmacophore-based scaffold hopping was performed to mitigate safety concerns associated with T-036. The ring opening of T-036 resulted in another potent GCS inhibitor with a lower toxicological risk, T-690, which reduced glucosylceramide in a dose-dependent manner in the plasma and cortex of mice. Finally, we discuss the structural aspects of the compounds that impart a unique inhibition mode and lower the cardiovascular risk.

Long-term safety and effectiveness of velaglucerase alfa in Gaucher disease: 6-year interim analysis of a post-marketing surveillance in Japan

BACKGROUND

Gaucher disease (GD) is caused by reduced lysosomal enzyme β-glucocerebrosidase activity. Heterogeneous genotypes and phenotypes have been observed within GD types and across ethnicities. Enzyme replacement therapy is generally recommended for patients with type 1 GD, the least severe form of GD. In Japan, velaglucerase alfa has a broad indication covering type 1, 2 or 3 GD.  METHODS: All patients with type 1, 2, or 3 GD administered velaglucerase alfa 60 U/kg every 2 weeks via intravenous infusion after its launch date in Japan in 2014, were enrolled in a non-interventional, observational post-marketing surveillance (PMS). Individual patient data were reported via case report forms (CRFs). Key safety endpoints investigated included the incidence of infusion-related reactions (IRRs), the safety of velaglucerase alfa in patients with types 2 and 3 GD, from patients under one year of age to elderly patients (≥ 65 years of age). Long-term efficacy was also assessed.  RESULTS: In total, 53 patients with GD were registered. CRFs were available for 41 (77.4%) patients at the 6-year interim analysis. Fourteen adverse drug reactions (ADRs) were reported in seven patients. All reported ADRs occurred in patients with type 2 GD. ADRs were reported by 63.6% (7/11) of patients with type 2 GD. Ten ADRs were reported in five patients aged < 4 years. No elderly patients experienced any ADR during the surveillance period. Five ADRs occurring in three (10.0%) patients were classified as IRRs, with one case of vomiting (moderate severity) resulting in treatment discontinuation. Ten serious adverse events were reported in five (16.7%) patients. Three fatal events were considered to be unrelated to treatment with velaglucerase alfa. Platelet counts increased after the administration of velaglucerase alfa and were generally maintained within the normal range over the administration period. Among eleven patients tested for neutralizing anti-velaglucerase alfa antibodies, two (18.2%) were assessed as positive results.  CONCLUSION: PMS data from patients with types 1-3 GD in Japan indicate that long-term treatment with velaglucerase alfa was well-tolerated and associated with increased platelet counts, which is consistent with observations made in studies outside of Japan.

TRIAL REGISTRATION

NCT03625882 registered July 2014.

The Future of Fetal Surgery

The field of fetal medicine has evolved significantly over the past several decades. Our ability to identify and treat the unborn patient has been shaped by advancements in imaging technology, genetic diagnosis, an improved understanding of fetal physiology, and the development and optimization of in utero surgical techniques. The future of the field will be shaped by medical innovators pushing for the continued refinement of minimally invasive surgical technique, the application of pioneering technologies such as robotic surgery and in utero stem cell and gene therapies, and the development of innovative ex utero fetal support systems.

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.

Movement Disorders and Liver Disease

The association of movement disorders with structural or functional hepatic disease occurs in three principal scenarios: (1) combined involvement of both organ systems from a single disease entity, (2) nervous system dysfunction resulting from exposure to toxic compounds in the setting of defective hepatic clearance, or (3) hepatic and/or neurological injury secondary to exposure to exogenous drugs or toxins. An important early step in the workup of any patient with combined movement disorders and liver disease is the exclusion of Wilson's disease. Diagnostic delay remains common for this treatable disorder, and this has major implications for patient outcomes. Thereafter, a structured approach integrating variables such as age of onset, tempo of progression, nature and severity of liver involvement, movement disorder phenomenology, exposure to drugs/toxins and laboratory/neuroimaging findings is key to ensuring timely diagnosis and disease‐specific therapy. Herein, we provide an overview of disorders which may manifest with a combination of movement disorders and liver disease, structured under the three headings as detailed above. In each section, the most common disorders are discussed, along with important clinical pearls, suggested diagnostic workup, differential diagnoses and where appropriate, treatment considerations.

A new brain-penetrant glucosylceramide synthase inhibitor as potential Therapeutics for Gaucher disease

Gaucher disease (GD), the most common lysosomal storage disorders, is caused by GBA gene mutations resulting in glycosphingolipids accumulations in various tissues, such as the brain. While suppressing glycosphingolipid accumulation is the central strategy for treating peripheral symptoms of GD, there is no effective treatment for the central nervous system symptoms. As glycosphingolipid biosynthesis starts from ceramide glycosylation by glucosylceramide synthase (GCS), inhibiting GCS in the brain is a promising strategy for neurological GD. Herein, we discovered T-036, a potent and brain-penetrant GCS inhibitor with a unique chemical structure and binding property. T-036 does not harbor an aliphatic amine moiety and has a noncompetitive inhibition mode to the substrates, unlike other known inhibitors. T-036 exhibited sufficient exposure and a significant reduction of glucosylsphingolipids in the plasma and brain of the GD mouse model. Therefore, T-036 could be a promising lead molecule for treating central nervous system symptoms of GD.

Clinicogenetic Profile, Treatment Modalities, and Mortality Predictors of Gaucher Disease: A 15-Year Retrospective Study

INTRODUCTION

Gaucher disease (GD) is a rare autosomal recessive lysosomal storage disorder, in which biallelic pathogenic variants in the Glucosidase beta acid (GBA) gene result in defective functioning of glucosylceramidase that causes deposition of glucocerebroside in cells. GD has 3 major types namely, non-neuronopathic (type I), acute neuronopathic (type II), and chronic neuronopathic (type III). Definite treatment options are limited and expensive. They succumb early to the disease, if untreated. There is paucity of studies from the Indian subcontinent, which elicit the factors resulting in their premature mortality.

MATERIALS AND METHODS

A retrospective study was carried out in a tertiary care setting of South India to assess the clinical profile, mutation spectrum, and various management strategies (only supportive therapy, enzyme replacement therapy [ERT], substrate reduction therapy [SRT] haematopoietic stem cell transplant [HSCT]), and mortality predictors of patients with GD from 2004 to 2019. A Kaplan-Meier survival curve was plotted. In silico predictions were performed for novel variants.

RESULTS

There were 60 patients with all types of GD seen over the study period of 15 years. Their median age at diagnosis was 2 years. The median follow-up was for 5 years (interquartile range [IQR] = 2-8). The overall mortality rate was 35%; however, it was only 10% in those receiving definite treatment. Mortality was higher (47.5%) by more than 4 folds in those only on supportive therapy. The median survival from the time of diagnosis was 6.3 years (IQR = 3.5-10.8) in the definite treatment group and 3.5 years (IQR = 1-5) in those on supportive therapy. The Kaplan-Meier survival analysis showed significant (p value 0.001) mortality difference between these groups. The multiple logistic regression analysis found the neuronopathic type (OR = 5) and only supportive therapy (OR = 6.3) to be the independent risk factors for premature mortality.

CONCLUSION

GD is a rare disease with a high mortality rate, if left untreated. ERT and SRT are the definitive treatments which increase the survival. In resource-limited settings like India, with higher prevalence of the neuronopathic type, HSCT may be a more suitable definitive treatment option, due to its one-time intervention and cost, assuming similar efficacy to ERT. However, the efficacy and safety of HSCT in GD needs to be established further by substantial patient numbers undergoing it.

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.

Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease

Gaucher Disease (GD), which is the most common lysosomal storage disorder, is caused by bi-allelic mutations in GBA1-a gene that encodes the lysosomal hydrolase β-glucocerebrosidase (GCase). The neuronopathic forms of GD (nGD) are characterized by severe neurological abnormalities that arise during gestation or early in infancy. Using GD-induced pluripotent stem cell (iPSC)-derived neuronal progenitor cells (NPCs), we have previously reported that neuronal cells have neurodevelopmental defects associated with the downregulation of canonical Wnt signaling. In this study, we report that GD NPCs display elevated levels of Dkk1, which is a secreted Wnt antagonist that prevents receptor activation. Dkk1 upregulation in mutant NPCs resulted in an increased degradation of β-catenin, and there was a concomitant reduction in lysosomal numbers. Consistent with these results, incubation of the mutant NPCs with recombinant Wnt3a (rWnt3a) was able to outcompete the excess Dkk1, increasing β-catenin levels and rescuing lysosomal numbers. Furthermore, the incubation of WT NPCs with recombinant Dkk1 (rDkk1) phenocopied the mutant phenotype, recapitulating the decrease in β-catenin levels and lysosomal depletion seen in nGD NPCs. This study provides evidence that downregulation of the Wnt/β-catenin pathway in nGD neuronal cells involves the upregulation of Dkk1. As Dkk1 is an extracellular Wnt antagonist, our results suggest that the deleterious effects of Wnt/β-catenin downregulation in nGD may be ameliorated by the prevention of Dkk1 binding to the Wnt co-receptor LRP6, pointing to Dkk1 as a potential therapeutic target for GBA1-associated neurodegeneration.

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.

Small Molecule Chaperones for the Treatment of Gaucher Disease and GBA1-Associated Parkinson Disease

Parkinson disease, the second most common movement disorder, is a complex neurodegenerative disorder hallmarked by the accumulation of alpha-synuclein, a neural-specific small protein associated with neuronal synapses. Mutations in the glucocerebrosidase gene (GBA1), implicated in the rare, autosomal recessive lysosomal disorder Gaucher disease, are the most common known genetic risk factor for Parkinson disease. Insights into the inverse relationship between glucocerebrosidase and alpha-synuclein have led to new therapeutic approaches for the treatment of Gaucher disease and GBA1-associated Parkinson disease. Unlike the current drugs used to treat Gaucher disease, which are highly expensive and do not cross the blood-brain-barrier, new small molecules therapies, including competitive and non-competitive chaperones that enhance glucocerebrosidase levels are being developed to overcome these limitations. Some of these include iminosugars, ambroxol, other competitive glucocerebrosidase inhibitors, and non-inhibitory chaperones or activators that do not compete for the active site. These drugs, which have been shown in different disease models to increase glucocerebrosidase activity, could have potential as a therapy for Gaucher disease and GBA1- associated Parkinson disease. Some have been demonstrated to reduce α-synuclein levels in pre-clinical studies using cell-based or animal models of GBA1-associated Parkinson disease, and may also have utility for idiopathic Parkinson disease.

Characterization of the visceral and neuronal phenotype of 4L/PS-NA mice modeling Gaucher disease

Gaucher disease is caused by a deficiency in glucocerebrosidase that can result in non-neuronal as well as neuronal symptoms. Common visceral symptoms are an increased organ size, specifically of the spleen, and glucosylceramide as well as glucosylsphingosine substrate accumulations as a direct result of the glucocerebrosidase deficiency. Neuronal symptoms include motor deficits and strong alterations in the cerebellum. To evaluate the effect of new compounds for the treatment of this devastating disease, animal models are needed that closely mimic the human phenotype. The 4L/PS-NA mouse as model of Gaucher disease is shown to present reduced glucocerebrosidase activity similar to human cases but an in-depth characterization of the model was still not performed. We therefore analyzed 4L/PS-NA mice for visceral alterations, motor deficits and also neuronal changes like glucocerebrosidase activity, substrate levels and neuroinflammation. A special focus was set at pathological changes of the cerebellum. Our results show that 4L/PS-NA mice have strongly enlarged visceral organs that are infiltrated by enlarged leukocytes and macrophages. Furthermore, animals present strong motor deficits that are accompanied by increased glucosylceramide and glucosylsphingosine levels in the brain, astrocytosis and activated microglia in the cortex and hippocampus as well as reduced calbindin levels in the cerebellum. The latter was directly related to a strong Purkinje cell loss. Our results thus provide a detailed characterization of the 4L/PS-NA mouse model over age showing the translational value of the model and validating its usefulness for preclinical efficiency studies to evaluate new compounds against Gaucher disease.

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.

mTOR hyperactivity mediates lysosomal dysfunction in Gaucher's disease iPSC-neuronal cells

Bi-allelic GBA1 mutations cause Gaucher's disease (GD), the most common lysosomal storage disorder. Neuronopathic manifestations in GD include neurodegeneration, which can be severe and rapidly progressive. GBA1 mutations are also the most frequent genetic risk factors for Parkinson's disease. Dysfunction of the autophagy-lysosomal pathway represents a key pathogenic event in GBA1-associated neurodegeneration. Using an induced pluripotent stem cell (iPSC) model of GD, we previously demonstrated that lysosomal alterations in GD neurons are linked to dysfunction of the transcription factor EB (TFEB). TFEB controls the coordinated expression of autophagy and lysosomal genes and is negatively regulated by the mammalian target of rapamycin complex 1 (mTORC1). To further investigate the mechanism of autophagy-lysosomal pathway dysfunction in neuronopathic GD, we examined mTORC1 kinase activity in GD iPSC neuronal progenitors and differentiated neurons. We found that mTORC1 is hyperactive in GD cells as evidenced by increased phosphorylation of its downstream protein substrates. We also found that pharmacological inhibition of glucosylceramide synthase enzyme reversed mTORC1 hyperactivation, suggesting that increased mTORC1 activity is mediated by the abnormal accumulation of glycosphingolipids in the mutant cells. Treatment with the mTOR inhibitor Torin1 upregulated lysosomal biogenesis and enhanced autophagic clearance in GD neurons, confirming that lysosomal dysfunction is mediated by mTOR hyperactivation. Further analysis demonstrated that increased TFEB phosphorylation by mTORC1 results in decreased TFEB stability in GD cells. Our study uncovers a new mechanism contributing to autophagy-lysosomal pathway dysfunction in GD, and identifies the mTOR complex as a potential therapeutic target for treatment of GBA1-associated neurodegeneration.

Twenty- five years of biochemical diagnosis of Gaucher disease: the Egyptian experience

BACKGROUND

Gaucher disease is a rare multi-systemic metabolic disorder resulting from the deficiency of acid β-glucosidase activity, with consequent accumulation of glucocerebroside. Less than 15% of mean normal acid β-glucosidase activity in leukocytes is the gold standard for the diagnosis of Gaucher disease, and is generally supplemented by a massive elevation in chitotriosidase activity. We report here our experience in the biochemical diagnosis of Gaucher disease by showing the heterogeneity of the activity of enzymes over 25 years from 1993-2017, through the analysis of 5128 clinically suspected Gaucher disease cases referred to the Biochemical Genetics Department, National Research Centre, as the main reference lab in Egypt for the diagnosis of Inherited Metabolic Disorders.

METHODS

Acid β-glucosidase and chitotriosidase activities were measured in all referred cases. Sphinogmylinase activity was estimated for all cases with normal β-glucosidase activity and moderate elevation of chitotriosidase.

RESULTS

Out of the 5128 suspected cases, 882 (17%) showed a deficiency in acid β-glucosidase activity, accompanied by a raised chitotriosidase activity, ranges (213-66700 umol/l/h) and mean (7255 umol/l/h). Deficient chitotriosidase activity was found in 9 patients (1%) with low β-glucosidase. 451 cases were diagnosed with acid sphingomyelinase deficiency patients (8.8%).

CONCLUSION

Other biochemical markers are needed in addition to chitotriosidase for the diagnosis and follow up. Molecular testing was done to a relatively small number but needs to be done to all diagnosed patients as many mutations are known to predict the course of the disease.

Glucocerebrosidase and its relevance to Parkinson disease

Mutations in GBA1, the gene encoding the lysosomal enzyme glucocerebrosidase, are among the most common known genetic risk factors for the development of Parkinson disease and related synucleinopathies. A great deal is known about GBA1, as mutations in GBA1 are causal for the rare autosomal storage disorder Gaucher disease. Over the past decades, significant progress has been made in understanding the genetics and cell biology of glucocerebrosidase. A least 495 different mutations, found throughout the 11 exons of the gene are reported, including both common and rare variants. Mutations in GBA1 may lead to degradation of the protein, disruptions in lysosomal targeting and diminished performance of the enzyme in the lysosome.

Gaucher disease is phenotypically diverse and has both neuronopathic and non-neuronopathic forms. Both patients with Gaucher disease and heterozygous carriers are at increased risk of developing Parkinson disease and Dementia with Lewy Bodies, although our understanding of the mechanism for this association remains incomplete. There appears to be an inverse relationship between glucocerebrosidase and α-synuclein levels, and even patients with sporadic Parkinson disease have decreased glucocerebrosidase. Glucocerebrosidase may interact with α-synuclein to maintain basic cellular functions, or impaired glucocerebrosidase could contribute to Parkinson pathogenesis by disrupting lysosomal homeostasis, enhancing endoplasmic reticulum stress or contributing to mitochondrial impairment. However, the majority of patients with GBA1 mutations never develop parkinsonism, so clearly other risk factors play a role. Treatments for Gaucher disease have been developed that increase visceral glucocerebrosidase levels and decrease lipid storage, although they have yet to properly address the neurological defects associated with impaired glucocerebrosidase. Mouse and induced pluripotent stem cell derived models have improved our understanding of glucocerebrosidase function and the consequences of its deficiency. These models have been used to test novel therapies including chaperone proteins, histone deacetylase inhibitors, and gene therapy approaches that enhance glucocerebrosidase levels and could prove efficacious in the treatment of forms of parkinsonism. Consequently, this rare monogenic disorder, Gaucher disease, provides unique insights directly applicable to our understanding and treatment of Parkinson disease, a common and complex neurodegenerative disorder.

Can GBA1-Associated Parkinson Disease Be Modeled in the Mouse?

Homozygous and heterozygous mutations in GBA1, the gene implicated in Gaucher disease, increase the risk and severity of Parkinson disease (PD). We evaluated the design, phenotype, strengths, and limitations of current GBA1-associated PD mouse models. Although faithful modeling of a genetic risk factor poses many challenges, the different approaches taken were successful in revealing predisposing abnormalities in heterozygotes for GBA1 mutations and demonstrating the deleterious effects of GBA1 impairment on the PD course in PD models. GBA1-PD models differ in key parameters, with no single model recapitulating all aspects of the GBA1-PD puzzle, emphasizing the importance of selecting the proper in vivo model depending on the specific molecular mechanism or potential therapy being studied.

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.

Lysosomal Leukodystrophies Lysosomal Storage Diseases Associated With White Matter Abnormalities

The leukodystrophies are a group of genetic metabolic diseases characterized by an abnormal development or progressive degeneration of the myelin sheath. The myelin is a complex sheath composed of several macromolecules covering axons as an insulator. Each of the leukodystrophies is caused by mutations in genes encoding enzymes that are involved in myelin production and maintenance. The lysosomal storage diseases are inborn disorders of compartmentalized cellular organelles with broad clinical manifestations secondary to the progressive accumulation of undegraded macromolecules within lysosomes and related organelles. The more than 60 different lysosomal storage diseases are rare diseases; however, collectively, the incidence of lysosomal storage diseases ranges just over 1 in 2500 live births. The majority of lysosomal storage diseases are associated with neurologic manifestations including developmental delay, seizures, acroparesthesia, motor weakness, and extrapyramidal signs. These inborn organelle disorders show wide clinical variability affecting individuals from all age groups. In addition, several of neurologic, also known as neuronopathic, lysosomal storage diseases are associated with some level of white matter disease, which often triggers the diagnostic investigation. Most lysosomal storage diseases are autosomal recessively inherited and few are X-linked, with females being at risk of presenting with mild, but clinically relevant neurologic manifestations. Biochemical assays are the basis of the diagnosis and are usually confirmed by molecular genetic testing. Novel therapies have emerged. However, most affected patients with lysosomal storage diseases have only supportive management to rely on. A better understanding of the mechanisms resulting in the leukodystrophy will certainly result in innovative and efficacious disease-modifying therapies.

Ophthalmological findings in Gaucher disease

Gaucher disease is an autosomal recessive lysosomal storage disorder caused by mutations in the gene GBA1, which encodes the lysosomal protein glucocerebrosidase. Patients with Gaucher disease generally have a variety of clinical manifestations ranging from visceral to neurological involvement and some develop ocular involvement. The most commonly affected organs include the spleen, liver, and bone. Moreover, patients often have hepatosplenomegaly, thrombocytopenia, anemia, and bone involvement related to deficient glucocerebrosidase and the subsequent accumulation of glucosylceramide and glucosylsphingosine in cells. A subset of patients develops neurological manifestations, including seizures, myoclonic epilepsy, and progressive neurodegeneration. Eye involvement tends to be less common and presents with diverse clinical findings. These rare and variable ocular manifestations, involving the vitreous, retina, cornea, uvea, conjunctiva and eye movements, can pose a diagnostic challenge for clinicians, especially those not familiar with the disorder. In this review, we explore the different ophthalmologic findings reported in patients with Gaucher disease, aiming to facilitate diagnosis and expedite treatment for patients presenting with ocular manifestations of this rare disorder.

Lysosomal storage disease overview

The lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders that are caused for the most part by enzyme deficiencies within the lysosome resulting in accumulation of undegraded substrate. This storage process leads to a broad spectrum of clinical manifestations depending on the specific substrate and site of accumulation. Examples of LSDs include the mucopolysaccharidoses, mucolipidoses, oligosaccharidoses, Pompe disease, Gaucher disease, Fabry disease, the Niemann-Pick disorders, and neuronal ceroid lipofuscinoses. This review summarizes the main clinical features, diagnosis, and management of LSDs with an emphasis on those for which treatment is available.

Inborn errors of metabolism

Inborn errors of metabolism, also known as inherited metabolic diseases, constitute an important group of conditions presenting with neurologic signs in newborns. They are individually rare but collectively common. Many are treatable through restoration of homeostasis of a disrupted metabolic pathway. Given their frequency and potential for treatment, the clinician should be aware of this group of conditions and learn to identify the typical manifestations of the different inborn errors of metabolism. In this review, we summarize the clinical, laboratory, electrophysiologic, and neuroimaging findings of the different inborn errors of metabolism that can present with florid neurologic signs and symptoms in the neonatal period.

Lysosomal storage disease overview

The lysosomal storage diseases (LSDs) are a group of inherited metabolic disorders that are caused for the most part by enzyme deficiencies within the lysosome resulting in accumulation of undegraded substrate. This storage process leads to a broad spectrum of clinical manifestations depending on the specific substrate and site of accumulation. Examples of LSDs include the mucopolysaccharidoses, mucolipidoses, oligosaccharidoses, Pompe disease, Gaucher disease, Fabry disease, the Niemann-Pick disorders, and neuronal ceroid lipofuscinoses. This review summarizes the main clinical features, diagnosis, and management of LSDs with an emphasis on those for which treatment is available.

The heat shock protein amplifier arimoclomol improves refolding, maturation and lysosomal activity of glucocerebrosidase

BACKGROUND

Gaucher Disease is caused by mutations of the GBA gene which encodes the lysosomal enzyme acid beta-glucosidase (GCase). GBA mutations commonly affect GCase function by perturbing its protein homeostasis rather than its catalytic activity. Heat shock proteins are well known cytoprotective molecules with functions in protein homeostasis and lysosomal function and their manipulation has been suggested as a potential therapeutic strategy for GD. The investigational drug arimoclomol, which is in phase II/III clinical trials, is a well-characterized HSP amplifier and has been extensively clinically tested. Importantly, arimoclomol efficiently crosses the blood-brain-barrier presenting an opportunity to target the neurological manifestations of GD, which remains without a disease-modifying therapy.

METHODS

We used a range of biological and biochemical in vitro assays to assess the effect of arimoclomol on GCase activity in ex vivo systems of primary fibroblasts and neuronal-like cells from GD patients.

FINDINGS

We found that arimoclomol induced relevant HSPs such as ER-resident HSP70 (BiP) and enhanced the folding, maturation, activity, and correct cellular localization of mutated GCase across several genotypes including the common L444P and N370S mutations in primary cells from GD patients. These effects where recapitulated in a human neuronal model of GD obtained by differentiation of multipotent adult stem cells.

INTERPRETATION

These data demonstrate the potential of HSP-targeting therapies in GCase-deficiencies and strongly support the clinical development of arimoclomol as a potential therapeutic option for the neuronopathic forms of GD.

FUNDING

The research was funded by Orphazyme A/S, Copenhagen, Denmark.

Genotypes and phenotypes in 20 Chinese patients with type 2 Gaucher disease

BACKGROUND

Gaucher disease (GD) is one of the most common lysosomal storage diseases resulting from a deficiency of glucocerebrosidase. Three main types have been described, with type 2 being the most rare and severe form. Here we investigated the clinical symptoms and mutation spectrum in 20 unrelated type 2 GD patients.

METHOD

The diagnosis of GD was based on the acid β-glucocerebrosidase (GBA) enzyme activity and direct sequencing of the GBA gene. GBA activity was measured in leukocytes and the GBA gene was amplified by a polymerase chain reaction (PCR). For patient 7, the GBA gene was analyzed by PCR as well as quantitative real-time PCR.

RESULTS

The age of onset was under 12 months for all patients. All patients experienced severe neurological involvement. A total of 19 different GBA gene mutations were identified, including 6 novel mutations: two were exonic point mutations, c.1127T > C (p.Phe376Ser), c.1418T > G (p.Val473Gly); one was splicing error, ISV7-1G > C; one was insertion, c.717_718insACAG; and the other two were a gross deletion that involved exon 6 and a recombinant allele. The most prevalent mutation was Leu483Pro, which constituted 42.5% of all mutant alleles and was associated with a neurological form in Chinese GD patients as calculated by a Fisher's exact test.

CONCLUSION

The clinical characteristics of Chinese type 2 GD were consistent with reports from other ethnic populations. We identified 6 novel mutations that contribute to the spectrum of GBA gene mutations. Our study confirmed that GD patients with the Leu483Pro allele were prone to experience neurological symptoms.

Four Gaucher disease type II patients with three novel mutations: a single centre experience from Turkey

Gaucher disease is the most common lysosomal storage disorder due to glucosylceramidase enzyme deficiency. There are three subtypes of the disease. Neurological involvement accompanies visceral and haematological findings only in type II and type III Gaucher patients. Type II is the acute progressive neuronopathic form which is the most severe and rare subtype. Clinical findings are recognized prenatally or in the first months of life and followed by death within the first two years of age. Among our 81 Gaucher patients, we identified 4 (4,9%) type II patients in our metabolic centre. This rate is significantly higher than the rate reported in the literature (<1%). Three of the patients had novel mutations, one of them was a collodion baby and the other one was mistyped as type III due to its atypical presentation at the beginning and he was treated with ERT for 8 months. In this report, we present our type II Gaucher patients with three novel mutations and one perinatal lethal form with generalized ichthyosis which is a very rare disorder. Additionally, we would like to highlight the phenotypic heterogeneity not only between the subtypes, also even in the same type.

Diagnosis and Management of Gaucher Disease in India – Consensus Guidelines of the Gaucher Disease Task Force of the Society for Indian Academy of Medical Genetics and the Indian Academy of Pediatrics

Justification

Gaucher disease (GD) is amongst the most frequently occurring lysosomal storage disorder in all ethnicities. The clinical manifestations and natural history of GD is highly heterogeneous with extreme geographic and ethnic variations. The literature on GD has paucity of information and optimal management guidelines for Indian patients.

Process

Gaucher Disease Task Force was formed under the auspices of the Society for Indian Academy of Medical Genetics. Invited experts from various specialties formulated guidelines for the management of patients with GD. A writing committee was formed and the draft guidelines were circulated by email to all members for comments and inputs. The guidelines were finalized in December 2016 at the annual meeting of the Indian Academy of Medical Genetics.

Objectives

These guidelines are intended to serve as a standard framework for treating physicians and the health care systems for optimal management of Gaucher disease in India and to define unique needs of this patient population.

Recommendations

Manifestations of GD are protean and a high index of suspicion is essential for timely diagnosis. Patients frequently experience diagnostic delays during which severe irreversible complications occur. Leucocyte acid β-glucosidase activity is mandatory for establishing the diagnosis of Gaucher disease; molecular testing can help identify patients at risk of neuronopathic disease. Enzyme replacement therapy for type 1 and type 3 Gaucher disease is the standard of care. Best outcomes are achieved by early initiation of therapy before onset of irreversible complications. However, in setting of progressive neurological symptoms such as seizures and or/neuroregression, ERT is not recommended, as it cannot cross the blood brain barrier. The recommendations herein are for diagnosis, for initiation of therapy, therapeutic goals, monitoring and follow up of patients. We highlight that prevention of recurrence of the disease through genetic counseling and prenatal diagnosis is essential in India, due to uniformly severe phenotypes encountered in our population.

Perinatal Lethal Gaucher Disease due to RecNcil Recombinant Mutation in the GBA Gene Presenting with Hydrops Fetalis and Severe Congenital Anemia

A 35-year-old woman presented at 27-week gestation with hypertension and pedal edema. Antenatal scan showed hydrops fetalis and growth restriction. Cordocentesis showed severe fetal anemia. This was treated with multiple in utero blood transfusions with no clinically significant improvement and intrauterine death occurred at 28 weeks. Perinatal autopsy confirmed severe hydrops with hepatosplenomegaly and visceral effusions. Microscopic examination of the reticuloendothelial organs showed widespread infiltration by large mono- and multinucleate histiocytic cells with fibrillary appearance (“Gaucher cells”). DNA extracted from fetal tissue was submitted for analysis by next generation sequencing which revealed homozygosity for the RecNcil mutation in the GBA gene. Both parents were found to be heterozygous for the variant. The case report highlights a severe form of Gaucher disease with histopathological and molecular confirmation that presents with hydrops fetalis and severe refractory anemia. It also emphasizes the importance of perinatal autopsy coupled with exome sequencing in confirming syndromic diagnosis in the modern area.