GBA, Gaucher Disease, and Parkinson's Disease: From Genetic to Clinic to New Therapeutic Approaches

Lewy pathology formation in patient-derived GBA1 Parkinson's disease midbrain organoids

Fibrillary aggregation of α-synuclein in Lewy body inclusions and nigrostriatal dopaminergic neuron degeneration define Parkinson's disease neuropathology. Mutations in GBA1, encoding glucocerebrosidase, are the most frequent genetic risk factor for Parkinson's disease. However, the lack of reliable experimental models able to reproduce key neuropathological signatures has hampered clarification of the link between mutant glucocerebrosidase and Parkinson's disease pathology. Here, we describe an innovative protocol for the generation of human induced pluripotent stem cell-derived midbrain organoids containing dopaminergic neurons with nigral identity that reproduce characteristics of advanced maturation. When applied to patients with GBA1-related Parkinson's disease, this method enabled the differentiation of midbrain organoids recapitulating dopaminergic neuron loss and fundamental features of Lewy pathology observed in human brains, including the generation of α-synuclein fibrillary aggregates with seeding activity that also propagate pathology in healthy control organoids. Concurrently, we found that the retention of mutant glucocerebrosidase in the endoplasmic reticulum and increased levels of its substrate, glucosylceramide, are determinants of α-synuclein aggregation into Lewy body-like inclusions, and the reduction of glucocerebrosidase activity accelerated α-synuclein pathology by promoting fibrillary α-synuclein deposition. Finally, we demonstrated the efficacy of ambroxol and GZ667161 (two modulators of the glucocerebrosidase pathway in clinical development for the treatment of GBA1-related Parkinson's disease) in reducing α-synuclein pathology in this model, supporting the use of midbrain organoids as a relevant preclinical platform for investigational drug screening.

A PheWAS approach to identify associations of GBA1 variants with comprehensive phenotypes beyond neurological diseases

Given the established association between numerous GBA1 variants and specific neurological diseases, we extended the exploration by a phenome-wide association study to assess the impact of GBA1 variants on a wider spectrum of health-related traits. We identified 41 phenotypes associated with GBA1 variants, 39 of which were unreported, including 21 non-neurological and 20 neurological phenotypes. Based on variant-level association tests, we found beyond the neurological phenotypes particularly decreased gray-white matter contrast measures across 13 distinct brain regions, the non-coding variant rs9628662 was associated with six non-neurological traits such as hypermetropia. Another non-coding variant rs3115534 showed associations with eight biomarkers of multiple categories, and an increased risk of benign digestive neoplasms. Notably, compared to protein-coding variant p.T408M, the rs3115534 had opposing effects on three hematological biomarkers. Additionally, gene-level association analyses revealed significant associations with three neurological diseases including Parkinson's disease. The findings demonstrated that GBA1 variants significantly impact various health-related traits.

LONG-NEXT: A new accurate and efficient NGS-based method for GBA1 analysis in Parkinson disease

INTRODUCTION

GBA1 variants are the most common genetic risk factor for Parkinson disease (PD). Sequencing of GBA1 on a large scale represents a burdensome task with currently adopted diagnostic techniques, namely Sanger sequencing and conventional short read next generation sequencing (sr-NGS). The high degree of sequence homology between GBA1 and its pseudogene GBA1LP is the major driver behind this complexity, leading to false positive and false negative results. We designed, optimized and validated LONG-NEXT, a new NGS-based strategy to streamline large scale GBA1 sequencing.

METHODS

LONG-NEXT relies on a specific long-range PCR, encompassing the whole GBA1 gene, in one fragment (6.5 kb), followed by short-read NGS and a tailored bioinformatic pipeline masking the GBA1LP sequence on the reference genome.

RESULTS

This protocol was optimized and tested on selected cases suspected of diagnostic mistakes by conventional testing (n = 13) and then validated on consecutively collected PD patients already screened either by Sanger sequencing (n = 101) or conventional sr-NGS (n = 294). LONG-NEXT reanalysis of 13 patients disclosed: 3 false positive cases due to mismapping of pseudogene reads on GBA1, 4 false homozygotes due to PCR-related allele dropout events, and 6 false negative cases, due to misalignment of GBA1 reads against the pseudogene or PCR-related allele dropout events. The validation phase disclosed one additional false homozygote in the Sanger cohort, and one false negative result in the sr-NGS cohort.

CONCLUSION

LONG-NEXT is a reliable, fast, cost-effective alternative for GBA1 sequencing and may prove strategic in light of current genotype-based tailored therapies specifically targeting GBA1-PD patients.

Comprehensive analysis of SLC17A5 variants in large European cohorts reveals no association with Parkinson's disease risk

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopaminergic neuron loss and α-synuclein aggregation. Aging is the primary risk factor, with both rare and common genetic variants playing a role. Previous studies have implicated lysosomal storage disorder (LSD)-related genes, including SLC17A5, in PD susceptibility.

OBJECTIVE

This study aimed to investigate the association of SLC17A5 variants, including rare and common variants and the FSASD-associated p.Arg39Cys missense variant, with PD risk in large European ancestry cohorts.

METHODS

Rare variant burden analyses were performed at minor allele frequency (MAF) thresholds of ≤1 % and ≤0.1 % in 7,184 PD cases and 51,650 controls using whole-genome and whole-exome sequencing data. Association testing of the p.Arg39Cys variant was conducted across five cohorts, encompassing both Finnish and non-Finnish Europeans. Common variant associations were examined using summary statistics from the largest European GWAS of PD.

RESULTS

No significant association was observed between rare SLC17A5 variants and PD at either MAF threshold. The p.Arg39Cys variant, though enriched in Finnish Europeans, showed no significant association with PD across several cohorts. Similarly, common SLC17A5 variants (MAF ≥1%) were not associated with PD risk.

CONCLUSION

Our findings do not support a role for SLC17A5 variants in PD susceptibility. While lysosomal dysfunction is central to PD pathogenesis, its contribution appears pathway-specific, with SLC17A5 unlikely to influence risk. Larger, multiethnic studies and functional analyses are needed to further investigate sialic acid metabolism in PD and related disorders.

Challenges in Gaucher disease: Perspectives from an expert panel

This focused review concentrates on eight topics of high importance for Gaucher disease (GD) clinicians and researchers: 1) The consideration of GD as distinct types rather than a spectrum. A review of the literature clearly supports the view that there are distinct types of GD. Type 1 is characterized by the absence of primary neuronopathic involvement, while types 2 and 3 are characterized by progressive primary neuronopathic disease. 2) Neurologic and neuronopathic manifestations. A growing body of evidence indicates that the peripheral nervous system may be involved in GD type 1 and that there may also be signs and symptoms of central nervous system (CNS) disease in this group. However, GD type 1 is characterized by the absence of primary neuronopathic disease, whereas GD types 2 and 3 are characterized by progressive, albeit variable, primary neuronopathic disease. Abnormalities in saccadic eye movements have been suggested as being diagnostic for neuronopathic GD, but they may also occur in GD type 1 and in other inflammatory diseases. 3) The importance of whole GBA1 sequencing. This approach is superior to exome sequencing because of potential effects of deep intronic variants on gene expression. It also has the capacity to detect variant alleles that might be missed with gene panels. 4) Monoclonal gammopathy of undetermined significance (MGUS). The risks of MGUS, multiple myeloma, and non-Hodgkin's lymphoma are elevated in patients with GD compared to the general population and strong evidence indicates that lyso-Gb1 stimulates the formation of monoclonal immunoglobulins (M-protein) in patients with GD and MGUS. 5) Pulmonary involvement in GD. Pulmonary complications can be identified through spirometry in up to 45 % of patients with GD type 1 and 55 % of those with GD type 3. Limited evidence exists that enzyme replacement therapy (ERT) reduces the severity of these complications in patients with GD type 1. 6) Gaucheromas. These may occur in patients with GD types 1 or 3, but there is little detailed information about their inception, mechanisms underlying growth, cellular organization, and biochemical activities, and no definitive guidance for their management. Gaucheromas behave like benign (i.e. non-metastasizing) neoplasms, and it may be reasonable to classify them as such. 7) Bone and joint involvement. Dual-energy X-ray absorptiometry scans alone are insufficient for monitoring all changes in bone that may occur in patients with GD. Quantitative magnetic resonance imaging (MRI) techniques using Dixon quantitative chemical shift imaging have provided results that correlate with GD severity scores, bone complications, and biomarkers for GD bone involvement. Thoracic kyphosis is a common complication of GD types 1 and 3, and there is very limited information regarding the effects of ERT or substrate synthesis inhibition therapy (SSIT) on this condition. 8) Treatment initiation, selection, combination, and switching. Prompt initiation of treatment in pediatric patients is important as GD can lead to impaired growth, lower peak bone mass, and delayed puberty. These adverse outcomes can often be ameliorated or prevented with timely treatment. Either ERT or eliglustat, a SSIT agent, is suitable as first-line treatment of adults with GD. Studies of switching from ERT to eliglustat, or between different ERT products, have indicated that changing treatment is safe, although efficacy outcomes vary. A critical remaining issue is the lack of treatments capable of reaching the CNS to slow or halt the progression of neuronopathic disease in patients with GD type 2 or 3 and potentially reduce the risk of Parkinson's disease in GD type 1 patients and heterozygotes for GBA1 variants.

Natural history of inflammation and impaired autophagy in children with Gaucher disease identified by newborn screening

Introduction

Gaucher disease is a lysosomal storage disease due to deficiency of glucocerebrosidase, leading to the accumulation of glucosylceramide, particularly in macrophages. In addition to storage, secondary abnormalities such as inflammation, cellular stress, and impaired autophagy may contribute to the disease pathogenesis. The onset and course of progression of these secondary abnormalities remains unclear. Owing to the increasingly widespread newborn screening programs, diagnosis can be made at a presymptomatic stage. Understanding the early natural course of the disease is important for optimal monitoring and management of such at-risk individuals.The aim of our study is to investigate secondary abnormalities in very young children with type 1 Gaucher disease identified through neonatal screening.

Materials and methods

We enrolled five children (<4 years old) with type I Gaucher disease in a presymptomatic stage and not receiving therapy. We assessed plasma cytokine profiles (TNFα, IL1β, and IL6 by ELISA), activation of pro-inflammatory p38 mitogen-activated protein kinase (MAPK) and the abundance of LC3-II as indicator of autophagic flux, by immunoblotting.

Results

All subjects exhibited elevated TNFα (mean 21.74 μmol/L, SD 37.48, range 2.37-88.72 μmol/L). The other cytokines analyzed were within normal range. Cellular stress (activation of p38) was present in the child with higher glucosylsphingosine (GluSph) accumulation. Additionally, all subjects showed a significant reduction in LC3-II (mean 88 %, SD 9 %, range 77-98 %), indicating reduced autophagic flux.

Discussion

We have identified the presence of inflammation with inhibition of autophagic flux in presymptomatic young children with a genetically confirmed high-risk of developing Gaucher disease. These findings contribute insights into the early course of Gaucher disease and support the management of at-risk individuals identified by newborn screening. Therapeutic interventions including specific enzyme replacement or other means to address inflammation or autophagy could delay or prevent the onset of symptomatic disease and consequential disability. Further clinical studies are warranted to explore these possibilities.

Increased α-synuclein phosphorylation and oligomerization and altered enzymes in plasma of patients with Parkinson's disease

The brain of patients with Parkinson's disease (PD) was characterized by increased phosphorylation and oligomerization of α-synuclein (α-syn) and altered activity of enzymes regulating α-syn phosphorylation and oligomerization. Whether increased α-syn phosphorylation and oligomerization as well as related enzyme changes can be detected in the plasma of PD patients remains unclear. Here, we showed that human α-syn proteins incubated in PD plasma formed more oligomerized α-syn (O-α-syn) and phosphorylated α-syn (pS-α-syn) than those in healthy control (HC) plasma. Receiver operating characteristic (ROC) curve indicated that α-syn oligomerization rate and phosphorylation rate discriminated PD patients well from HC subjects. Moreover, they were both positively correlated with Hoehn and Yahr staging and polo-like kinase 2 (PLK2, an enzyme promoting α-syn phosphorylation) levels, and negatively correlated with protein phosphatase 2A levels (PP2A, an enzyme dephosphorylating α-syn) and glucocerebrosidase (GCase, an enzyme whose deficiency causes α-syn oligomerization) activity and ceramide (a product of GCase and a natural PP2A activator) levels. The above results suggest that increased α-syn oligomerization and phosphorylation rates and related enzyme changes can be detected in PD plasma and used to discriminate PD patients from HC subjects and predict PD progression.

Early-onset Parkinson's disease in a patient with a rare homozygous pathogenic GBA1 variant and no Gaucher disease symptoms

Parkinson's disease (PD) is a multifaceted neurodegenerative disorder with both non-motor and motor symptoms. Variants in the glucosylceramidase beta 1 (GBA1) gene are the strongest genetic risk factor for PD, while homozygous or compound heterozygous variants in this gene classically cause Gaucher disease (GD). This study presents an early-onset PD patient with a homozygous GBA1 deletion. Whole-exome sequencing (WES) was performed, and the identified variant was validated via Sanger sequencing. The variant was classified according to ACMG guidelines and ClinGen updates. The patient, a Brazilian female of mixed ethnicity, exhibited the full spectrum of classical motor and non-motor PD symptoms without evident hallmarks of GD. The identified homozygous GBA1 variant (NM_000157.4:c.222_224del; p.T75del; rs761621516) has a very low global allele frequency (0.00003284) and is associated with reduced enzymatic activity. This variant exhibits a founder effect among individuals of African descent. This case highlights an intricate genotype-phenotype landscape for GBA1 variants, underscoring the role of homozygous GBA1 variants in PD pathogenesis.

TTC7A missense variants in intestinal disease can be classified by molecular and cellular phenotypes

Biallelic mutations in tetratricopeptide repeat domain 7A (TTC7A) give rise to intestinal and immune disorders. However, our understanding of the genotype-phenotype relationship is limited, because TTC7A variants are mostly compound heterozygous and the disease phenotypes are highly diverse. This study aims to clarify how different TTC7A variants impact the severity of intestinal epithelial disorders. We individually characterized the molecular and cellular consequences of 11 different TTC7A missense mutations in TTC7A knockout Caco-2 cells. We examined variant-specific RNA expression profiles, TTC7A protein abundance, and endoplasmic reticulum (ER) stress by using RNA sequencing and imaging flow cytometry. For six variants we detected no significant alterations on these assays, suggesting that protein function may not be severely compromised. However, for five variants we observed molecular phenotypes, with overlapping gene expression signatures between specific variants. Remarkably, the TTC7AE71K variant displayed a unique expression profile, along with reduced TTC7A RNA and protein expression, which set it apart from all other variants. The findings from this study offer a better understanding of the role of specific TTC7A variants in disease and provide a framework for the classification of the variants based on the severity of impact. We propose a classification system for TTC7A variants that could help diagnosis, guide future treatment decisions and may aid in developing effective molecular therapies for patients that carry specific TTC7A variants.

Genetic evidence for the liver-brain axis: lipid metabolism and neurodegenerative disease risk

BACKGROUND

The liver‒brain axis is critical in neurodegenerative diseases (NDs), with lipid metabolism influencing neuroinflammation and microglial function. A systematic investigation of the genetic relationship between lipid metabolism abnormalities and ND, namely, Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS), is lacking. To assess potential causal links between ND and six lipid parameters, two-sample Mendelian randomization (MR) was used.

METHODS

Large-scale European ancestry GWAS data for lipid parameters and ND (AD, ALS, PD, and MS) were used. Genetic variants demonstrating significant correlations (P < 5 × 10-8) with lipid metabolism parameters were identified and employed as instrumental variables (IVs) after proper validation. The research incorporated UK Biobank genomic data to examine associations between genetic variants and lipid metabolism parameters. The analysis included primary MR, sensitivity analyses, and multivariable MR, which considered potential mediators.

RESULTS

MR via the inverse-variance weighted method revealed causal effects of cholesterol (CHOL, OR = 1.10, 95% CI: 1.03-1.18, P = 4.23 × 10⁻3) and low-density lipoprotein cholesterol (LDLC, OR = 1.10, 95% CI: 1.03-1.17, P = 3.28 × 10⁻3) on the risk of ALS, which were validated across multiple methods. Potential correlations were observed between ApoB and ALS and inversely correlated with AD, whereas no significant associations were found for PD or MS. CHOL and LDLC associations with ALS demonstrated no significant heterogeneity or pleiotropy, supporting their reliability.

CONCLUSIONS

Higher CHOL and LDLC levels were associated with increased ALS risk, suggesting a potential causal link, and supporting the liver‒brain axis hypothesis in ND. Current genetic evidence does not support a significant role for lipid metabolism in PD and MS etiology, suggesting the relationship between lipid metabolism and other NDs may be more complex and warrants further investigation.

Association between the Amplification Parameters of the α-Synuclein Seed Amplification Assay and Clinical and Genetic Subtypes of Parkinson's Disease

BACKGROUND

α-Synuclein seed amplification assay on cerebrospinal fluid (CSF-αSyn-SAA) has shown high accuracy for Parkinson's disease (PD) diagnosis. The analysis of CSF-αSyn-SAA parameters may provide useful insight to dissect the heterogeneity of synucleinopathies.

OBJECTIVE

To assess differences in CSF-αSyn-SAA amplification parameters in participants with PD stratified by rapid eye movement (REM) sleep behavior disorder (RBD), dysautonomia, GBA, and LRRK2 variants.

METHODS

Clinical and CSF-αSyn-SAA data from the Parkinson's Progression Marker Initiative dataset were used. CSF-αSyn-SAA parameters included maximum fluorescence (Fmax), time to reach 50% of Fmax (T50), time to threshold (TTT), slope, and area under the curve (AUC). Sporadic PD (n = 371) was stratified according to RBD and dysautonomia (DysA) symptoms. Genetic PD included carriers of pathogenic variants of GBA (GBA-PD, n = 52) and LRRK2 (LRRK2-PD, n = 124) gene.

RESULTS

CSF-αSyn-SAA was positive in 77% of LRRK2-PD, 92.3% of GBA-PD, and 93.8% of sporadic PD. The LRRK2-PD cohort showed longer T50 and TTT, and smaller AUC than GBA-PD (P = 0.029, P = 0.029, P = 0.016, respectively) and sporadic PD (P = 0.034, P = 0.033, P = 0.014, respectively). In the sporadic cohort, CSF-αSyn-SAA parameters were similar between PD with (n = 157) and without (n = 190) RBD, whereas participants with DysA (n = 193) presented shorter T50 (P = 0.026) and larger AUC (P = 0.029) than those without (n = 150).

CONCLUSION

CSF-αSyn-SAA parameters vary across genetic and non-genetic PD subtypes at the group level. These differences are mostly driven by the presence of LRRK2 variants and DysA. Significant overlaps in the amplification parameter values exist between groups and limit their use at the individual level. Further studies are necessary to understand the mechanisms of CSF-αSyn-SAA parameter differences. © 2024 International Parkinson and Movement Disorder Society.

A Global Perspective of GBA1-Related Parkinson's Disease: A Narrative Review

Parkinson's disease (PD) is considered to be the second most prominent neurodegenerative disease and has a global prevalence. Glucocerebrosidase (GBA1) gene mutations represent a significant hereditary risk factor for the development of PD and have a profound impact on the motor and cognitive progression of the disease. The aim of this review is to summarize the literature data on the prevalence, type, and peculiarities of GBA1 mutations in populations of different ethnic backgrounds. We reviewed articles spanning the 2000-2024 period. GBA1-related PD has a worldwide distribution. It has long been recognized that pathogenic GBA1 mutations are particularly common in certain ethnic populations, including PD patients of Ashkenazi Jewish ancestry. Moreover, a considerable number of studies focused on European ancestry patients from Europe and North America have revealed a high proportion (up to 15%) of carriers among the PD population. GBA1 mutations also appear to play an important role in patient groups with an East Asian background, although the frequency of specific variants may differ as compared to those of European ancestry. Notably, the assessment of underrepresented populations in other parts of Asia (including India) and Latin America is in the spotlight of current research, while a variant with a newly described pathogenic mechanism has been reported in Sub-Saharan Africans. Given the importance of GBA1 mutations for PD genetics and clinical phenotype, a focused assessment of the prevalence and type of GBA1 variants in distinct ethnic populations will possibly inform ongoing PD-related clinical studies and facilitate upcoming therapeutic trials.

Comparing GBA1-Parkinson's disease and idiopathic Parkinson's disease: α-Synuclein oligomers and synaptic density as biomarkers in the skin biopsy

The main genetic risk factors for Parkinson's disease (PD) are presently represented by variants in GBA1 gene encoding for the β-glucocerebrosidase (GCase). Searching for a peripheral biomarker that can be used for selecting and monitoring patients in clinical trials targeting GBA1-associated PD (GBA1-PD) is a current challenge. We previously demonstrated that α-synuclein oligomers expressed as proximity ligation assay (PLA) score in synaptic terminals of skin biopsy are a reliable biomarker for distinguishing idiopathic PD (iPD) from healthy controls (HC). This cross-sectional study investigates an unexplored cohort of GBA1-PD (n = 27) compared to 28 HC, and 36 iPD cases to (i) analyze α-synuclein oligomers and quantify them throughout PLA score, (ii) investigate GCase expression in brain and synaptic terminals targeting the sweat gland, (iii) unravel indicators that could differentiate patients with specific GBA1 mutations. PLA score discriminates GBA1-PD from HC with sensitivity = 88.9% (95% CI 70.84-97.65), specificity = 88.5% (95% CI 69.85-97.55), and PPV = 88.9% (95% CI 73.24-95.90), AUC value = 0.927 (95% CI 0.859-0.996). No difference was found between GBA1-PD patients and iPD, suggesting a common pathological pathway based on α-synuclein oligomers. GCase score did not differ in GBA1-PD, iPD, and HC in the synaptic terminals, whereas a positive correlation was found between PLA score and GCase score. Moreover, a significant increase in synaptic density was observed in GBA1-PD compared to iPD and HC (P < 0.0001). Employing ROC curve to discriminate GBA1-PD from iPD, we found an AUC value for synaptic density = 0.855 (95% CI 0.749-0.961) with sensitivity = 85.2% (95% CI 66.27%-95.81%), specificity = 77.1% (95% CI 59.86%-89.58%), and PPV = 74.19% (60.53%-84.35%). The highest synaptic density values were observed in p.N409S patients. This work points out to the value of both PLA score and synaptic density in distinguishing GBA1-PD from iPD and to their potential to stratify and monitor patients in the context of new pathway-specific therapeutic options.

Comprehensive genome analysis and variant detection at scale using DRAGEN

Research and medical genomics require comprehensive, scalable methods for the discovery of novel disease targets, evolutionary drivers and genetic markers with clinical significance. This necessitates a framework to identify all types of variants independent of their size or location. Here we present DRAGEN, which uses multigenome mapping with pangenome references, hardware acceleration and machine learning-based variant detection to provide insights into individual genomes, with ~30 min of computation time from raw reads to variant detection. DRAGEN outperforms current state-of-the-art methods in speed and accuracy across all variant types (single-nucleotide variations, insertions or deletions, short tandem repeats, structural variations and copy number variations) and incorporates specialized methods for analysis of medically relevant genes. We demonstrate the performance of DRAGEN across 3,202 whole-genome sequencing datasets by generating fully genotyped multisample variant call format files and demonstrate its scalability, accuracy and innovation to further advance the integration of comprehensive genomics. Overall, DRAGEN marks a major milestone in sequencing data analysis and will provide insights across various diseases, including Mendelian and rare diseases, with a highly comprehensive and scalable platform.

Investigating the Impact of the Parkinson's-Associated GBA1 E326K Mutation on β-Glucocerebrosidase Dimerization and Interactome Dynamics Through an In Silico Approach

Heterozygous mutations or genetic variants in the GBA1 gene, which encodes for the β-glucocerebrosidase (GCase), a lysosomal hydrolase enzyme, may increase the risk of Parkinson's disease (PD) onset. The heterozygous E326K form is one of the most common genetic risk factors for PD worldwide, but, to date, the underlying molecular mechanisms remain unclear. Here, we investigate the effect of the E326K on the structure, stability, dimerization process, and interaction mode with some proteins of the interactome of GCase using multiple molecular dynamics (MD) simulations at pH 5.5 and pH 7.0 to mimic the lysosomal and endoplasmic reticulum environments, respectively. The analysis of the MD trajectories highlights that the E326K mutation did not significantly alter the structural conformation of the catalytic dyad but significantly makes the structure of the dimeric complexes unstable, especially at lysosomal pH, potentially impacting the organization of the quaternary structure. Furthermore, the E326K mutation significantly impacts protein interactions by altering the binding mode with the activator Saposin C (SapC), reducing the binding affinity with the inhibitor α-Synuclein (α-Syn), and increasing the affinity for the Lysosomal integral membrane protein-2 (LIMP-2) transporter.

Parkinson's families project: a UK-wide study of early onset and familial Parkinson's disease

The Parkinson's Families Project is a UK-wide study aimed at identifying genetic variation associated with familial and early-onset Parkinson's disease (PD). We recruited individuals with a clinical diagnosis of PD and age at motor symptom onset ≤45 years and/or a family history of PD in up to third-degree relatives. Where possible, we also recruited affected and unaffected relatives. We analysed DNA samples with a combination of single nucleotide polymorphism (SNP) array genotyping, multiplex ligation-dependent probe amplification (MLPA), and whole-genome sequencing (WGS). We investigated the association between identified pathogenic mutations and demographic and clinical factors such as age at motor symptom onset, family history, motor symptoms (MDS-UPDRS) and cognitive performance (MoCA). We performed baseline genetic analysis in 718 families, of which 205 had sporadic early-onset PD (sEOPD), 113 had familial early-onset PD (fEOPD), and 400 had late-onset familial PD (fLOPD). 69 (9.6%) of these families carried pathogenic variants in known monogenic PD-related genes. The rate of a molecular diagnosis increased to 28.1% in PD with motor onset ≤35 years. We identified pathogenic variants in LRRK2 in 4.2% of families, and biallelic pathogenic variants in PRKN in 3.6% of families. We also identified two families with SNCA duplications and three families with a pathogenic repeat expansion in ATXN2, as well as single families with pathogenic variants in VCP, PINK1, PNPLA6, PLA2G6, SPG7, GCH1, and RAB32. An additional 73 (10.2%) families were carriers of at least one pathogenic or risk GBA1 variant. Most early-onset and familial PD cases do not have a known genetic cause, indicating that there are likely to be further monogenic causes for PD.

Genetic influence on microstructure integrity and motor progression in Parkinson's disease

BACKGROUND

Up to 10 % of Parkinson's disease (PD) populations carry a genetic risk variant, which may not only increase one's chance of developing PD but also affect disease presentation and progression. We hypothesize motor impairment in genetic carriers of PD correlate to different patterns of microstructural changes over time.

DESIGN/METHODS

Data were accessed from the Parkinson's Progression Markers Initiative (PPMI) project. Connectometry analyses were performed for GBA1+ PD, LRRK2+ PD, and sporadic PD correlating white matter structural changes, as measured by quantitative anisotropy (QA), with motor impairment, as measured by MDS-UPDRS III.

RESULTS

There was a negative correlation between QA and MDS-UPDRS III in all 3 cohorts at 48 months. In GBA1+ PD (n = 12), the white matter tracts identified were cortical and subcortical, while in the LRRK2+ PD (n = 18) and sporadic PD (n = 45) cohorts white tracts identified were primarily subcortical and within the brainstem.

CONCLUSIONS

Our findings highlight the association between motor symptom progrerssion and structural connectivity in individuals with GBA1+ PD, LRRK2+ PD, and sporadic PD. Due to the small sample size, larger studies are needed in the future to confirm the findings.

[Lysosomal storage disorders - Fabry disease and Gaucher disease]

Lysosomal storage disorders (LSD) are a heterogenous group of inborn errors of metabolism due to lysosomal malfunction. LSDs affect 1 in 5000 live births, albeit every LSD itself has a low incidence. The most common LSDs are Fabry disease and Gaucher disease. The underlying cause mainly is an enzyme deficiency but may also be due to defects in transport or activation proteins, which result in progressive intra- and extra-lysosomal accumulation of undegraded storage material. The lysosomes play a key role in degradation and cellular recycling of macromolecules. Besides disturbance of cellular function, substrate accumulation may result in secondary toxic and/or inflammatory processes. For treatment of Fabry and Gaucher disease, several therapeutic approaches are approved including enzyme replacement therapy, chaperon therapy for Fabry disease and substrate reduction therapy for Gaucher disease.

A PIKfyve modulator combined with an integrated stress response inhibitor to treat lysosomal storage diseases

Lysosomal degradation pathways coordinate the clearance of superfluous and damaged cellular components. Compromised lysosomal degradation is a hallmark of many degenerative diseases, including lysosomal storage diseases (LSDs), which are caused by loss-of-function mutations within both alleles of a lysosomal hydrolase, leading to lysosomal substrate accumulation. Gaucher's disease, characterized by <15% of normal glucocerebrosidase function, is the most common LSD and is a prominent risk factor for developing Parkinson's disease. Here, we show that either of two structurally distinct small molecules that modulate PIKfyve activity, identified in a high-throughput cellular lipid droplet clearance screen, can improve glucocerebrosidase function in Gaucher patient-derived fibroblasts through an MiT/TFE transcription factor that promotes lysosomal gene translation. An integrated stress response (ISR) antagonist used in combination with a PIKfyve modulator further improves cellular glucocerebrosidase activity, likely because ISR signaling appears to also be slightly activated by treatment by either small molecule at the higher doses employed. This strategy of combining a PIKfyve modulator with an ISR inhibitor improves mutant lysosomal hydrolase function in cellular models of additional LSD.

Neurosteroid Levels in GBA Mutated and Non-Mutated Parkinson's Disease: A Possible Factor Influencing Clinical Phenotype?

Neurosteroids are pleiotropic molecules involved in various neurodegenerative diseases with neuroinflammation. We assessed neurosteroids' serum levels in a cohort of Parkinson's Disease (PD) patients with heterozygous glucocerebrosidase (GBA) mutations (GBA-PD) compared with matched cohorts of consecutive non-mutated PD (NM-PD) patients and healthy subjects with (GBA-HC) and without (NM-HC) GBA mutations. A consecutive cohort of GBA-PD was paired for age, sex, disease duration, Hoehn and Yahr stage, and comorbidities with a cohort of consecutive NM-PD. Two cohorts of GBA-HC and HC were also considered. Clinical assessment included the Movement Disorder Society revision of the Unified Parkinson's Disease Rating Scale (MDS-UPDRS) and the Montreal Cognitive Assessment (MoCA). Serum samples were processed and analyzed by liquid chromatography coupled with the triple quadrupole mass spectrometry. Twenty-two GBA-PD (males: 11, age: 63.68), 22 NM-PD (males: 11, age: 63.05), 14 GBA-HC (males: 8; age: 49.36), and 15 HC (males: 4; age: 60.60) were studied. Compared to NM-PD, GBA-PD showed more hallucinations and psychosis (p < 0.05, Fisher's exact test) and higher MDS-UPDRS part-II (p < 0.05). Most of the serum neurosteroids were reduced in both GBA-PD and NM-PD compared to the respective control cohorts, except for 5α-dihydroprogesterone. Allopregnanolone was the only neurosteroid significantly lower (p < 0.01, Dunn's test) in NM-PD compared to GBA-PD patients. Only in GBA-PD, allopregnanolone, and pregnanolone levels correlated (Spearman) with a more severe MDS-UPDRS part-III. Allopregnanolone levels also negatively correlated with MoCA scores, and pregnanolone levels correlated with more pronounced bradykinesia. This pilot study provides the first observation of changes in neurosteroid peripheral levels in GBA-PD. The involvement of the observed changes in the development of neuropsychological and motor symptoms of GBA-PD deserves further attention.

Evaluation of a Liquid Chromatography-Tandem Mass Spectrometry Method for the Analysis of Glucosylceramide and Galactosylceramide Isoforms in Cerebrospinal Fluid of Parkinson's Disease Patients

Mutations in GBA1, encoding glucocerebrosidase beta 1 (GCase), are the most common genetic risk factor for Parkinson's disease (PD). GCase dysfunction leads to an accumulation of glucosylceramide (GluCer) substrates in different organs and fluids. Despite the challenges in quantifying GluCer isoforms in biological samples, their potential clinical interest as PD biomarkers justifies the development of robust assays. An extensively evaluated high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for quantifying 14 GluCer and galactosylceramide (GalCer) isoforms in human cerebrospinal fluid (CSF) samples is presented. Sample pretreatment, HPLC, and MS/MS parameters were optimized. Evaluation was performed according to the recommendations of the Clinical and Laboratory Standards Institute and European Medicines Agency guidelines. Four 7-point calibration curves were generated, with a linearity interval from 2.5 to 200 nM (R2 ≥ 0.995). The limit of quantification was set at 5 nM. Between-run precision and accuracy were up to 12.5 and 9%, respectively. After method validation, we measured the levels of GluCer and GalCer isoforms in CSF human samples, including 6 healthy controls (HC), 22 idiopathic GBA1 wild-type PD (iPD) patients, and 5 GBA1-associated PD (PD-GBA) patients. GluCer/GalCer median ratios were found to be higher in the CSF of PD-GBA patients, particularly in severe GBA1 mutations, than those in iPD and HC. The observed trends in GluCer/GalCer ratios among groups provide novel information for the comprehensive analysis of sphingolipids as potential biomarkers of PD.

GBA-AAV mitigates sleep disruptions and motor deficits in mice with REM sleep behavior disorder

Sleep disturbances, including rapid eye movement sleep behavior disorder (RBD), excessive daytime sleepiness, and insomnia, are common non-motor manifestations of Parkinson's disease (PD). Little is known about the underlying mechanisms, partly due to the inability of current rodent models to adequately mimic the human PD sleep phenotype. Clinically, increasing studies have reported that variants of the glucocerebrosidase gene (GBA) increase the risk of PD. Here, we developed a mouse model characterized by sleep-wakefulness by injecting α-synuclein preformed fibronectin (PFF) into the sublaterodorsal tegmental nucleus (SLD) of GBA L444P mutant mice and investigated the role of the GBA L444P variant in the transition from rapid eye movement sleep behavior disorder to PD. Initially, we analyzed spectral correlates of REM and NREM sleep in GBA L444P mutant mice. Importantly, EEG power spectral analysis revealed that GBA L444P mutation mice exhibited reduced delta power during non-rapid eye movement (NREM) sleep and increased theta power (8.2-10 Hz) in active rapid eye movement (REM) sleep phases. Our study revealed that GBA L444P-mutant mice, after receiving PFF injections, exhibited increased sleep fragmentation, significant motor and cognitive dysfunctions, and loss of dopaminergic neurons in the substantia nigra. Furthermore, the over-expression of GBA-AAV partially improved these sleep disturbances and motor and cognitive impairments. In conclusion, we present the initial evidence that the GBA L444P mutant mouse serves as an essential tool in understanding the complex sleep disturbances associated with PD. This model further provides insights into potential therapeutic approaches, particularly concerning α-synuclein accumulation and its subsequent pathological consequences.

Artificial intelligence in Parkinson's disease: Early detection and diagnostic advancements

Parkinson's disease (PD) is the second most common neurodegenerative disorder, globally affecting men and women at an exponentially growing rate, with currently no cure. Disease progression starts when dopaminergic neurons begin to die. In PD, the loss of neurotransmitter, dopamine is responsible for the overall communication of neural cells throughout the body. Clinical symptoms of PD are slowness of movement, involuntary muscular contractions, speech & writing changes, lessened automatic movement, and chronic tremors in the body. PD occurs in both familial and sporadic forms and modifiable and non-modifiable risk factors and socioeconomic conditions cause PD. Early detectable diagnostics and treatments have been developed in the last several decades. However, we still do not have precise early detectable biomarkers and therapeutic agents/drugs that prevent and/or delay the disease process. Recently, artificial intelligence (AI) science and machine learning tools have been promising in identifying early detectable markers with a greater rate of accuracy compared to past forms of treatment and diagnostic processes. Artificial intelligence refers to the intelligence exhibited by machines or software, distinct from the intelligence observed in humans that is based on neural networks in a form and can be used to diagnose the longevity and disease severity of disease. The term Machine Learning or Neural Networks is a blanket term used to identify an emerging technology that is created to work in the way of a "human brain" using many intertwined neurons to achieve the same level of raw intelligence as that of a brain. These processes have been used for neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease, to assess the severity of the patient's condition. In the current article, we discuss the prevalence and incidence of PD, and currently available diagnostic biomarkers and therapeutic strategies. We also highlighted currently available artificial intelligence science and machine learning tools and their applications to detect disease and develop therapeutic interventions.

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.

Expanding the Spectrum of GBA1-Associated Neurodegenerative Diseases in an Italian Family

BACKGROUND

Heterozygous mutations in GBA1 gene are known as most common genetic risk factor for Parkinson's disease (PD). However, role of GBA1 mutations in non-α-synuclein disorders is unclear.

CASES

Case index, 76 year-old woman referred to our movement disorders outpatient clinic for 2-year history of gait impairment, falls and motor slowness, with partial response to levodopa. Clinical and instrumental examinations were consistent with Progressive Supranuclear Palsy-Corticobasal Syndrome (PSP-CBS). Case 2 is older sister reporting depressive symptoms; however, she had dementia (MMSE 18/30), gait apraxia and vertical supranuclear gaze palsy (VSNGP). Case 3 is her deceased older sister who had been diagnosed with Corticobasal Syndrome (CBS). Case 4, older brother had been diagnosed with Parkinson's disease-dementia (PDD) with good response to levodopa. Two affected living siblings harboring same genetic variant.

CONCLUSIONS

To our knowledge, this is the first family showing such intrafamilial variability ranging from CBS to PDD to dementia.

GBA moderates cognitive reserve's effect on cognitive function in patients with Parkinson's disease

BACKGROUND

Cognitive reserve (CR) involves an individual's ability to maintain cognitive vitality over their lifespan. Glucocerebrosidase (GBA) gene mutations contribute to additional effects on cognitive function in Parkinson's disease (PD) patients, but the interplay between GBA mutations and CR remains unclear. We investigated the interactions among CR, GBA, and diseases, aiming to examine whether the CR established at different stages interacts with specific genotypes to affect cognitive function.

METHODS

Three hundred and eighteen participants' CR indicators (i.e., education, occupation, and social function) and comprehensive neuropsychological function (i.e., tests for executive function, attention/working memory, visuospatial function, memory, and language) were evaluated.

RESULTS

We found that CR established in a specific life stage influences the individual's cognitive function, particularly in PD, based on their distinct GBA rs9628662 genotypes. Attention/working memory and memory performance are affected by occupational complexity in midlife in PD patients with the GG genotype (q < 0.0001; q < 0.0001) and healthy adults with the T genotype (q = 0.0440; q < 0.0001). Language is influenced by early education and occupation, and the effects of occupation are also observed in PD patients with the GG genotype (q = 0.0040) and in healthy adults carrying the T genotype (q = 0.0040).

CONCLUSIONS

CR, established at different life stages, can be influenced by the GBA rs9628662 genotype, impacting later-life cognition. Validating genotypes and incorporating genotype information when assessing cognitive reserve effects is crucial and can enhance targeted cognitive training.

Neurological symptoms in adults with Gaucher disease: a systematic review

INTRODUCTION

Gaucher disease (GD) is classically divided into three types, based on the presence or absence of neurological signs and symptoms. However, presentation can be highly variable in adulthood, and this aspect has not been adequately addressed in the literature so far. We performed a systematic literature review to analyze the entire spectrum of neurological manifestations in adult patients previously classified as GD type I, II, or III, evaluating the role of variants in different neurological manifestations.

METHODS

We searched databases for studies reporting clinical data of adult GD patients (age ≥ 18). Data extraction included GD types, GBA1 variants, age at disease onset and diagnosis, duration of GD, and age at onset and type of neurological symptoms reported.

RESULTS

Among 4190 GD patients from 85 studies, 555 exhibited neurological symptoms in adulthood. The median age at evaluation was 46.8 years (IQR 26.5), age at neurological symptoms onset was 44 years (IQR 35.1), and age at GD clinical onset was 23 years (IQR 23.4). Parkinsonism, including Parkinson's disease and Lewy Body dementia, was the most reported neurological manifestation. Other symptoms and signs encompassed oculomotor abnormalities, peripheral neuropathy, seizures, myoclonus, and cerebellar, cognitive and psychiatric symptoms. The genotype N370S/N370S mostly presented with Parkinsonism and the L444P variant with severe and earlier neurological symptoms.

CONCLUSION

The findings of this systematic review highlight: (1) the relevance of a comprehensive neurological assessment in GD patients, and (2) the importance of considering possible undiagnosed GD in adult patients with mild systemic symptoms presenting unexplained neurological symptoms.

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

INTRODUCTION

Gaucher's disease (GD) is caused by biallelic mutations in the GBA1 gene, leading to reduced glucocerebrosidase (GCase) activity and substrate (glucosylceramide and glucosylsphingosine, GlcSph) accumulation. GBA1 variant carriers are at risk of Parkinson's disease (PD), but only those with biallelic mutations cross the threshold of GCase reduction, leading to substrate accumulation and GD. The link between GBA1 mutations, GD and PD is not fully understood. Here we aimed at reporting the results of a large PD population screening with dried blood spot tests for GD.

METHODS

We measured GCase activity and GlcSph levels in 1344 PD patients with dried blood spot tests, and performed GBA1 genetic sequencing.

RESULTS

While the GCase activity was reduced in GBA1-PD carriers compared to wild type PD, GlcSph was increased in GBA1-PD compared to GBA1-controls, regardless of the underlying type of GBA1 variant. 13.6 % and 0.4 % of PD patients had mono- or biallelic GBA1 mutations respectively. GCase deficiency, lipid accumulation and clinical manifestations of GD was detected in five PD patients with biallelic GBA1 mutations, of whom four had a risk combined with a GD causing variant.

CONCLUSIONS

GlcSph appearing higher in PD may represent a reliable biomarker of the disease and deserves to be further investigated. This study highlights the importance of screening PD patients for possible underlying GD, which is a treatable condition that should not be missed. We diagnosed GD cases carrying a "risk" variant in one allele, which is an unprecedented finding deserving further investigation.

GBA1-Associated Parkinson's Disease Is a Distinct Entity

GBA1-associated Parkinson's disease (GBA1-PD) is increasingly recognized as a distinct entity within the spectrum of parkinsonian disorders. This review explores the unique pathophysiological features, clinical progression, and genetic underpinnings that differentiate GBA1-PD from idiopathic Parkinson's disease (iPD). GBA1-PD typically presents with earlier onset and more rapid progression, with a poor response to standard PD medications. It is marked by pronounced cognitive impairment and a higher burden of non-motor symptoms compared to iPD. Additionally, patients with GBA1-PD often exhibit a broader distribution of Lewy bodies within the brain, accentuating neurodegenerative processes. The pathogenesis of GBA1-PD is closely associated with mutations in the GBA1 gene, which encodes the lysosomal enzyme beta-glucocerebrosidase (GCase). In this review, we discuss two mechanisms by which GBA1 mutations contribute to disease development: 'haploinsufficiency,' where a single functional gene copy fails to produce a sufficient amount of GCase, and 'gain of function,' where the mutated GCase acquires harmful properties that directly impact cellular mechanisms for alpha-synuclein degradation, leading to alpha-synuclein aggregation and neuronal cell damage. Continued research is advancing our understanding of how these mechanisms contribute to the development and progression of GBA1-PD, with the 'gain of function' mechanism appearing to be the most plausible. This review also explores the implications of GBA1 mutations for therapeutic strategies, highlighting the need for early diagnosis and targeted interventions. Currently, small molecular chaperones have shown the most promising clinical results compared to other agents. This synthesis of clinical, pathological, and molecular aspects underscores the assertion that GBA1-PD is a distinct clinical and pathobiological PD phenotype, necessitating specific management and research approaches to better understand and treat this debilitating condition.

GBA-associated Parkinson's disease in Hungary: clinical features and genetic insights

INTRODUCTION

Parkinson's disease (PD) has a complex genetic background involving both rare and common genetic variants. Although a small percentage of cases show a clear Mendelian inheritance pattern, it is much more relevant to identify patients who present with a complex genetic profile of risk variants with different severity. The ß-glucocerebrosidase coding gene (GBA1) is recognized as the most frequent genetic risk factor for PD and Lewy body dementia, irrespective of reduction of the enzyme activity due to genetic variants.

METHODS

In a selected cohort of 190 Hungarian patients with clinical signs of PD and suspected genetic risk, we performed the genetic testing of the GBA1 gene. As other genetic hits can modify clinical features, we also screened for additional rare variants in other neurodegenerative genes and assessed the APOE-ε genotype of the patients.

RESULTS

In our cohort, we identified 29 GBA1 rare variant (RV) carriers. Out of the six different detected RVs, the highly debated E365K and T408M variants are composed of the majority of them (22 out of 32). Three patients carried two GBA1 variants, and an additional three patients carried rare variants in other neurodegenerative genes (SMPD1, SPG11, and SNCA). We did not observe differences in age at onset or other clinical features of the patients carrying two GBA1 variants or patients carrying heterozygous APOE-ε4 allele.

CONCLUSION

We need further studies to better understand the drivers of clinical differences in these patients, as this could have important therapeutic implications.

Efficacy of non-computerized cognitive rehabilitation in Parkinson's disease: A one year follow up study

In this study, we explored the effect of non-computerized cognitive rehabilitation in patients with Parkinson's disease in comparison with an intervention with elements of music therapy after the completion of a three-month program and one year after the end of the intervention. After the initial neuropsychological examination, the respondents were divided into two intervention groups. The experimental group (n = 26) underwent a twelve-week program of cognitive rehabilitation at a frequency of 60 minutes once a week. The control group (n = 27) underwent an intervention program with elements of music therapy at the same frequency. Respondents who underwent the cognitive rehabilitation program improved in the delayed recall from visual memory in the follow-up examination after the end of the cognitive intervention. One year after the end, the effect of cognitive rehabilitation persisted in delayed recall from visual memory and in executive mental flexibility. Cognitive rehabilitation is an effective approach to compensate for cognitive deficits in P D, but other approaches to cognitive stimulation may be equally effective.

Mutations in Glycosyltransferases and Glycosidases: Implications for Associated Diseases

Glycosylation, a crucial and the most common post-translational modification, coordinates a multitude of biological functions through the attachment of glycans to proteins and lipids. This process, predominantly governed by glycosyltransferases (GTs) and glycoside hydrolases (GHs), decides not only biomolecular functionality but also protein stability and solubility. Mutations in these enzymes have been implicated in a spectrum of diseases, prompting critical research into the structural and functional consequences of such genetic variations. This study compiles an extensive dataset from ClinVar and UniProt, providing a nuanced analysis of 2603 variants within 343 GT and GH genes. We conduct thorough MTR score analyses for the proteins with the most documented variants using MTR3D-AF2 via AlphaFold2 (AlphaFold v2.2.4) predicted protein structure, with the analyses indicating that pathogenic mutations frequently correlate with Beta Bridge secondary structures. Further, the calculation of the solvent accessibility score and variant visualisation show that pathogenic mutations exhibit reduced solvent accessibility, suggesting the mutated residues are likely buried and their localisation is within protein cores. We also find that pathogenic variants are often found proximal to active and binding sites, which may interfere with substrate interactions. We also incorporate computational predictions to assess the impact of these mutations on protein function, utilising tools such as mCSM to predict the destabilisation effect of variants. By identifying these critical regions that are prone to disease-associated mutations, our study opens avenues for designing small molecules or biologics that can modulate enzyme function or compensate for the loss of stability due to these mutations.

Early deficits in an in vitro striatal microcircuit model carrying the Parkinson's GBA-N370S mutation

Understanding medium spiny neuron (MSN) physiology is essential to understand motor impairments in Parkinson's disease (PD) given the architecture of the basal ganglia. Here, we developed a custom three-chambered microfluidic platform and established a cortico-striato-nigral microcircuit partially recapitulating the striatal presynaptic landscape in vitro using induced pluripotent stem cell (iPSC)-derived neurons. We found that, cortical glutamatergic projections facilitated MSN synaptic activity, and dopaminergic transmission enhanced maturation of MSNs in vitro. Replacement of wild-type iPSC-derived dopamine neurons (iPSC-DaNs) in the striatal microcircuit with those carrying the PD-related GBA-N370S mutation led to a depolarisation of resting membrane potential and an increase in rheobase in iPSC-MSNs, as well as a reduction in both voltage-gated sodium and potassium currents. Such deficits were resolved in late microcircuit cultures, and could be reversed in younger cultures with antagonism of protein kinase A activity in iPSC-MSNs. Taken together, our results highlight the unique utility of modelling striatal neurons in a modular physiological circuit to reveal mechanistic insights into GBA1 mutations in PD.

Hereditary spastic paraparesis type 46 (SPG46): new GBA2 variants in a large Italian case series and review of the literature

Hereditary spastic paraparesis (HSP) is a group of central nervous system diseases primarily affecting the spinal upper motor neurons, with different inheritance patterns and phenotypes. SPG46 is a rare, early-onset and autosomal recessive HSP, linked to biallelic GBA2 mutations. About thirty families have been described worldwide, with different phenotypes like complicated HSP, recessive cerebellar ataxia or Marinesco-Sjögren Syndrome. Herein, we report five SPG46 patients harbouring five novel GBA2 mutations, the largest series described in Italy so far. Probands were enrolled in five different centres and underwent neurological examination, clinical cognitive assessment, column imaging for scoliosis assessment, ophthalmologic examination, brain imaging, GBA2 activity in peripheral blood cells and genetic testing. Their phenotype was consistent with HSP, with notable features like upper gaze palsy and movement disorders. We review demographic, genetic, biochemical and clinical information from all documented cases in the existing literature, focusing on the global distribution of cases, the features of the syndrome, its variable presentation, new potential identifying features and the significance of measuring GBA2 enzyme activity.

Gaucher Disease Coexisting with Cytomegalovirus Infection: A Rare Presentation in an Infant

BACKGROUND Gaucher disease is a rare autosomal recessive disorder characterized by mutations in the glucocerebrosidase gene, resulting in deficient enzyme activity and accumulation of glucocerebroside in macrophages, which leads to pathological changes in affected organs. The atypical clinical manifestations of Gaucher disease often contribute to delays in diagnosis and treatment. CASE REPORT We present the case of a 4-month-old female infant admitted to the Department of Pediatrics with progressive hepatosplenomegaly since birth. Concurrently, she had cytomegalovirus infection and sensory neurological hearing loss. Gaucher disease diagnosis was confirmed through whole-exome sequencing and validated by a glucocerebrosidase activity test, revealing the mutation site as c.1448T>C. This report outlines the differential diagnosis process for Gaucher disease in this infant before confirmation, contributing valuable insights for early diagnosis. CONCLUSIONS Our case underscores the challenge of diagnosing Gaucher disease due to its atypical presentation. The coexistence of cytomegalovirus infection complicates the clinical picture, emphasizing the need for careful differential diagnosis. Unfortunately, delayed diagnosis is all too common in rare diseases like Gaucher disease, even when the clinical presentation is seemingly typical. This highlights the need for increased awareness and education within the medical community to facilitate early recognition, which is essential for prompt intervention and improved outcomes. This report contributes valuable clinical and genetic information, aiming to enhance awareness and deepen the understanding of Gaucher disease in infants, particularly those with concurrent infections.

Protocol for image-based small-molecule screen to identify neuroprotective compounds for dopaminergic neurons in zebrafish

Whole-organism-based screen holds promise for discovering biologically active compounds. However, high-content imaging is challenging due to the difficulty of positioning live animals and individual variability of neuron counts. Here, we present a protocol to identify neuroprotective compounds for dopaminergic neurons in zebrafish using an image-based small-molecule screen. We describe steps for raising larvae, agarose embedding, and treatment to induce neurodegeneration. We then detail procedures for live confocal imaging, image processing, and data analysis. For complete details on the use and execution of this protocol, please refer to Kim et al. (2021).1.

Genetics in Parkinson's disease, state-of-the-art and future perspectives

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disorder and is clinically characterized by the presence of motor (bradykinesia, rigidity, rest tremor and postural instability) and non-motor symptoms (cognitive impairment, autonomic dysfunction, sleep disorders, depression and hyposmia). The aetiology of PD is unknown except for a small but significant contribution of monogenic forms.

SOURCES OF DATA

No new data were generated or analyzed in support of this review.

AREAS OF AGREEMENT

Up to 15% of PD patients carry pathogenic variants in PD-associated genes. Some of these genes are associated with mendelian inheritance, while others act as risk factors. Genetic background influences age of onset, disease course, prognosis and therapeutic response.

AREAS OF CONTROVERSY

Genetic testing is not routinely offered in the clinical setting, but it may have relevant implications, especially in terms of prognosis, response to therapies and inclusion in clinical trials. Widely adopted clinical guidelines on genetic testing are still lacking and open to debate. Some new genetic associations are still awaiting confirmation, and selecting the appropriate genes to be included in diagnostic panels represents a difficult task. Finally, it is still under study whether (and to which degree) specific genetic forms may influence the outcome of PD therapies.

GROWING POINTS

Polygenic Risk Scores (PRS) may represent a useful tool to genetically stratify the population in terms of disease risk, prognosis and therapeutic outcomes.

AREAS TIMELY FOR DEVELOPING RESEARCH

The application of PRS and integrated multi-omics in PD promises to improve the personalized care of patients.

Role of GBA variants in Lewy body disease neuropathology

Rare and common GBA variants are risk factors for both Parkinson's disease (PD) and dementia with Lewy bodies (DLB). However, the degree to which GBA variants are associated with neuropathological features in Lewy body disease (LBD) is unknown. Herein, we assessed 943 LBD cases and examined associations of 15 different neuropathological outcomes with common and rare GBA variants. Neuropathological outcomes included LBD subtype, presence of a high likelihood of clinical DLB (per consensus guidelines), LB counts in five cortical regions, tyrosine hydroxylase immunoreactivity in the dorsolateral and ventromedial putamen, ventrolateral substantia nigra neuronal loss, Braak neurofibrillary tangle (NFT) stage, Thal amyloid phase, phospho-ubiquitin (pS65-Ub) level, TDP-43 pathology, and vascular disease. Sequencing of GBA exons revealed a total of 42 different variants (4 common [MAF > 0.5%], 38 rare [MAF < 0.5%]) in our series, and 165 cases (17.5%) had a copy of the minor allele for ≥ 1 variant. In analysis of common variants, p.L483P was associated with a lower Braak NFT stage (OR = 0.10, P < 0.001). In gene-burden analysis, presence of the minor allele for any GBA variant was associated with increased odds of a high likelihood of DLB (OR = 2.00, P < 0.001), a lower Braak NFT stage (OR = 0.48, P < 0.001), a lower Thal amyloid phase (OR = 0.55, P < 0.001), and a lower pS65-Ub level (β: -0.37, P < 0.001). Subgroup analysis revealed that GBA variants were most common in LBD cases with a combination of transitional/diffuse LBD and Braak NFT stage 0-II or Thal amyloid phase 0-1, and correspondingly that the aforementioned associations of GBA gene-burden with a decreased Braak NFT stage and Thal amyloid phase were observed only in transitional or diffuse LBD cases. Our results indicate that in LBD, GBA variants occur most frequently in cases with greater LB pathology and low AD pathology, further informing disease-risk associations of GBA in PD, PD dementia, and DLB.

Deep sequencing of proteotoxicity modifier genes uncovers a Presenilin-2/beta-amyloid-actin genetic risk module shared among alpha-synucleinopathies

Whether neurodegenerative diseases linked to misfolding of the same protein share genetic risk drivers or whether different protein-aggregation pathologies in neurodegeneration are mechanistically related remains uncertain. Conventional genetic analyses are underpowered to address these questions. Through careful selection of patients based on protein aggregation phenotype (rather than clinical diagnosis) we can increase statistical power to detect associated variants in a targeted set of genes that modify proteotoxicities. Genetic modifiers of alpha-synuclein (ɑS) and beta-amyloid (Aβ) cytotoxicity in yeast are enriched in risk factors for Parkinson's disease (PD) and Alzheimer's disease (AD), respectively. Here, along with known AD/PD risk genes, we deeply sequenced exomes of 430 ɑS/Aβ modifier genes in patients across alpha-synucleinopathies (PD, Lewy body dementia and multiple system atrophy). Beyond known PD genes GBA1 and LRRK2, rare variants AD genes (CD33, CR1 and PSEN2) and Aβ toxicity modifiers involved in RhoA/actin cytoskeleton regulation (ARGHEF1, ARHGEF28, MICAL3, PASK, PKN2, PSEN2) were shared risk factors across synucleinopathies. Actin pathology occurred in iPSC synucleinopathy models and RhoA downregulation exacerbated ɑS pathology. Even in sporadic PD, the expression of these genes was altered across CNS cell types. Genome-wide CRISPR screens revealed the essentiality of PSEN2 in both human cortical and dopaminergic neurons, and PSEN2 mutation carriers exhibited diffuse brainstem and cortical synucleinopathy independent of AD pathology. PSEN2 contributes to a common-risk signal in PD GWAS and regulates ɑS expression in neurons. Our results identify convergent mechanisms across synucleinopathies, some shared with AD.

Effects of Paraquat, Dextran Sulfate Sodium, and Irradiation on Behavioral and Cognitive Performance and the Gut Microbiome in A53T and A53T-L444P Mice

Heterozygous carriers of the glucocerebrosidase 1 (GBA) L444P Gaucher mutation have an increased risk of developing Parkinson's disease (PD). The GBA mutations result in elevated alpha synuclein (aSyn) levels. Heterozygous mice carrying one allele with the L444P mutation knocked-into the mouse gene show increased aSyn levels and are more sensitive to motor deficits following exposure to the neurotoxin (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) MPTP than wild-type mice. Paraquat (PQ), a herbicide, increases PD risk in most studies. Its effects on the brain involve alterations in the gut microbiome. Exposure to dextran sulfate sodium (DSS), a mouse model of colitis, can be used to determine whether gut microbiome alterations are sufficient to induce PD-relevant phenotypes. We rederived the A53T-L444P and A53T mouse lines to assess whether PQ, PQ in combination with radiation exposure (IR), and DSS have differential effects in A53T and A53T-L444P mice and whether these effects are associated with alterations in the gut microbiome. PQ and PQ + IR have differential effects in A53T and A53T-L444P mice. In contrast, effects of DSS are only seen in A53T-L444P mice. Exposure and genotype modulate the relationship between the gut microbiome and behavioral performance. The gut microbiome may be an important mediator of how environmental exposures or genetic mutations yield behavioral and cognitive impacts.

Synaptic dysfunction and extracellular matrix dysregulation in dopaminergic neurons from sporadic and E326K-GBA1 Parkinson's disease patients

Parkinson's disease (PD) is a neurodegenerative disease with both genetic and sporadic origins. In this study, we investigated the electrophysiological properties, synaptic activity, and gene expression differences in dopaminergic (DA) neurons derived from induced pluripotent stem cells (iPSCs) of healthy controls, sporadic PD (sPD) patients, and PD patients with E326K-GBA1 mutations. Our results demonstrate reduced sodium currents and synaptic activity in DA neurons derived from PD patients with E326K-GBA1 mutations, suggesting a potential contribution to PD pathophysiology. We also observed distinct electrophysiological alterations in sPD DA neurons, which included a decrease in synaptic currents. RNA sequencing analysis revealed unique dysregulated pathways in sPD neurons and E326K-GBA1 neurons, further supporting the notion that molecular mechanisms driving PD may differ between PD patients. In agreement with our previous reports, Extracellular matrix and Focal adhesion pathways were among the top dysregulated pathways in DA neurons from sPD patients and from patients with E326K-GBA1 mutations. Overall, our study further confirms that impaired synaptic activity is a convergent functional phenotype in DA neurons derived from PD patients across multiple genetic mutations as well as sPD. At the transcriptome level, we find that the brain extracellular matrix is highly involved in PD pathology across multiple PD-associated mutations as well as sPD.

Unraveling the Genetic Landscape of Neurological Disorders: Insights into Pathogenesis, Techniques for Variant Identification, and Therapeutic Approaches

Genetic abnormalities play a crucial role in the development of neurodegenerative disorders (NDDs). Genetic exploration has indeed contributed to unraveling the molecular complexities responsible for the etiology and progression of various NDDs. The intricate nature of rare and common variants in NDDs contributes to a limited understanding of the genetic risk factors associated with them. Advancements in next-generation sequencing have made whole-genome sequencing and whole-exome sequencing possible, allowing the identification of rare variants with substantial effects, and improving the understanding of both Mendelian and complex neurological conditions. The resurgence of gene therapy holds the promise of targeting the etiology of diseases and ensuring a sustained correction. This approach is particularly enticing for neurodegenerative diseases, where traditional pharmacological methods have fallen short. In the context of our exploration of the genetic epidemiology of the three most prevalent NDDs-amyotrophic lateral sclerosis, Alzheimer's disease, and Parkinson's disease, our primary goal is to underscore the progress made in the development of next-generation sequencing. This progress aims to enhance our understanding of the disease mechanisms and explore gene-based therapies for NDDs. Throughout this review, we focus on genetic variations, methodologies for their identification, the associated pathophysiology, and the promising potential of gene therapy. Ultimately, our objective is to provide a comprehensive and forward-looking perspective on the emerging research arena of NDDs.

The Impact of 90 Parkinson's Disease-Risk Single Nucleotide Polymorphisms on Urinary Bis(monoacylglycerol)phosphate Levels in the Prodromal and PD Cohorts

Parkinson's disease (PD) is a common neurodegenerative disorder with a prolonged prodromal phase. Higher urinary bis(monoacylglycerol)phosphate (BMP) levels associate with LRRK2 (leucine-rich repeat kinase 2) and GBA1 (glucocerebrosidase) mutations, and are considered as potential noninvasive biomarkers for predicting those mutations and PD progression. However, their reliability has been questioned, with inadequately investigated genetics, cohorts, and population. In this study, multiple statistical hypothesis tests were employed on urinary BMP levels and sequences of 90 PD-risk single nucleotide polymorphisms (SNPs) from Parkinson's Progression Markers Institution (PPMI) participants. Those SNPs were categorized into four groups based on their impact on BMP levels in various cohorts. Variants rs34637584 G/A and rs34637584 A/A (LRRK2 G2019S) were identified as the most relevant on increasing urinary BMP levels in the PD cohort. Meanwhile, rs76763715 T/T (GBA1) was the primary factor elevating BMP levels in the prodromal cohort compared to its T/C and C/C variants (N370S) and the PD cohort. Proteomics analysis indicated the changed transport pathways may be the reasons for elevated BMP levels in prodromal patients. Our findings demonstrated that higher urinary BMP levels alone were not reliable biomarkers for PD progression or gene mutations but might serve as supplementary indicators for early diagnosis and treatment.

Exploring the efficacy and safety of Ambroxol in Gaucher disease: an overview of clinical studies

Gaucher disease (GD) is mainly caused by glucocerebrosidase (GCase) enzyme deficiency due to genetic variations in the GBA1 gene leading to the toxic accumulation of sphingolipids in various organs, which causes symptoms such as anemia, thrombocytopenia, hepatosplenomegaly, and neurological manifestations. GD is clinically classified into the non-neuronopathic type 1, and the acute and chronic neuronopathic forms, types 2 and 3, respectively. In addition to the current approved GD medications, the repurposing of Ambroxol (ABX) has emerged as a prospective enzyme enhancement therapy option showing its potential to enhance mutated GCase activity and reduce glucosylceramide accumulation in GD-affected tissues of different GBA1 genotypes. The variability in response to ABX varies across different variants, highlighting the diversity in patients' therapeutic outcomes. Its oral availability and safety profile make it an attractive option, particularly for patients with neurological manifestations. Clinical trials are essential to explore further ABX's potential as a therapeutic medication for GD to encourage pharmaceutical companies' investment in its development. This review highlights the potential of ABX as a pharmacological chaperone therapy for GD and stresses the importance of addressing response variability in clinical studies to improve the management of this rare and complex disorder.

The Potentiality of Natural Products and Herbal Medicine as Novel Medications for Parkinson's Disease: A Promising Therapeutic Approach

As the global population ages, the prevalence of Parkinson's disease (PD) is steadily on the rise. PD demonstrates chronic and progressive characteristics, and many cases can transition into dementia. This increases societal and economic burdens, emphasizing the need to find effective treatments. Among the widely recognized causes of PD is the abnormal accumulation of proteins, and autophagy dysfunction accelerates this accumulation. The resultant Lewy bodies are also commonly found in Alzheimer's disease patients, suggesting an increased potential for the onset of dementia. Additionally, the production of free radicals due to mitochondrial dysfunction contributes to neuronal damage and degeneration. The activation of astrocytes and the M1 phenotype of microglia promote damage to dopamine neurons. The drugs currently used for PD only delay the clinical progression and exacerbation of the disease without targeting its root cause, and come with various side effects. Thus, there is a demand for treatments with fewer side effects, with much potential offered by natural products. In this study, we reviewed a total of 14 articles related to herbal medicines and natural products and investigated their relevance to possible PD treatment. The results showed that the reviewed herbal medicines and natural products are effective against lysosomal disorder, mitochondrial dysfunction, and inflammation, key mechanisms underlying PD. Therefore, natural products and herbal medicines can reduce neurotoxicity and might improve both motor and non-motor symptoms associated with PD. Furthermore, these products, with their multi-target effects, enhance bioavailability, inhibit antibiotic resistance, and might additionally eliminate side effects, making them good alternative therapies for PD treatment.

[Genetic characteristics and clinical analysis of 20 patients with Gaucher's disease]

Gaucher Disease (GD) is an autosomal recessive lysosomal storage disorder characterized by high heterogeneity. This study aimed to further understand the correlation between clinical phenotypes and genotypes in GD patients through a retrospective analysis of 20 cases in Shanxi Bethune Hospital, including their clinical manifestations, laboratory tests, enzyme studies, and genetic results. Among the 20 GD patients, 16 were classified as Type Ⅰ GD with a median age of diagnosis of 24 years, and 4 were classified as Type Ⅲ GD with a median age of diagnosis of 19 years. All patients exhibited splenomegaly and thrombocytopenia, with 16 patients showing skeletal imaging changes, and 5 of them presenting with bone pain symptoms. Genetic analysis revealed 15 distinct mutations, predominantly missense mutations, with L483P being the most prevalent (35.7%), followed by V414L, L303I, and F252I. Mutation sites were predominantly located in exon 7. Noteworthy findings included the first report of the S310G mutation by our research group and the first occurrence of the K196R mutation in the Chinese population. Additionally, the N227S mutation was implicated in a potential association with neuropathy. Despite advancements, Uncertainties still exist in the correlation between clinical phenotypes and genotypes in GD patients.

Analysis of rare Parkinson's disease variants in millions of people

Although many rare variants have been reportedly associated with Parkinson's disease (PD), many have not been replicated or have failed to replicate. Here, we conduct a large-scale replication of rare PD variants. We assessed a total of 27,590 PD cases, 6701 PD proxies, and 3,106,080 controls from three data sets: 23andMe, Inc., UK Biobank, and AMP-PD. Based on well-known PD genes, 834 variants of interest were selected from the ClinVar annotated 23andMe dataset. We performed a meta-analysis using summary statistics of all three studies. The meta-analysis resulted in five significant variants after Bonferroni correction, including variants in GBA1 and LRRK2. Another eight variants are strong candidate variants for their association with PD. Here, we provide the largest rare variant meta-analysis to date, providing information on confirmed and newly identified variants for their association with PD using several large databases. Additionally we also show the complexities of studying rare variants in large-scale cohorts.

Comprehensive and accurate genome analysis at scale using DRAGEN accelerated algorithms

Research and medical genomics require comprehensive and scalable solutions to drive the discovery of novel disease targets, evolutionary drivers, and genetic markers with clinical significance. This necessitates a framework to identify all types of variants independent of their size (e.g., SNV/SV) or location (e.g., repeats). Here we present DRAGEN that utilizes novel methods based on multigenomes, hardware acceleration, and machine learning based variant detection to provide novel insights into individual genomes with ~30min computation time (from raw reads to variant detection). DRAGEN outperforms all other state-of-the-art methods in speed and accuracy across all variant types (SNV, indel, STR, SV, CNV) and further incorporates specialized methods to obtain key insights in medically relevant genes (e.g., HLA, SMN, GBA). We showcase DRAGEN across 3,202 genomes and demonstrate its scalability, accuracy, and innovations to further advance the integration of comprehensive genomics for research and medical applications.

Secretome Analyses Identify FKBP4 as a GBA1-Associated Protein in CSF and iPS Cells from Parkinson's Disease Patients with GBA1 Mutations

Mutations in the GBA1 gene increase the risk of developing Parkinson's disease (PD). However, most carriers of GBA1 mutations do not develop PD throughout their lives. The mechanisms of how GBA1 mutations contribute to PD pathogenesis remain unclear. Cerebrospinal fluid (CSF) is used for detecting pathological conditions of diseases, providing insights into the molecular mechanisms underlying neurodegenerative disorders. In this study, we utilized the proximity extension assay to examine the levels of metabolism-linked protein in the CSF from 17 PD patients carrying GBA1 mutations (GBA1-PD) and 17 idiopathic PD (iPD). The analysis of CSF secretome in GBA1-PD identified 11 significantly altered proteins, namely FKBP4, THOP1, GLRX, TXNDC5, GAL, SEMA3F, CRKL, APLP1, LRP11, CD164, and NPTXR. To investigate GBA1-associated CSF changes attributed to specific neuronal subtypes responsible for PD, we analyzed the cell culture supernatant from GBA1-PD-induced pluripotent stem cell (iPSC)-derived midbrain dopaminergic (mDA) neurons. The secretome analysis of GBA1-PD iPSC-derived mDA neurons revealed that five differently regulated proteins overlapped with those identified in the CSF analysis: FKBP4, THOP1, GLRX, GAL, and CRKL. Reduced intracellular level of the top hit, FKPB4, was confirmed via Western Blot. In conclusion, our findings identify significantly altered CSF GBA1-PD-associated proteins with FKPB4 being firmly attributed to mDA neurons.