Generation and characterization of induced pluripotent stem cells from a Parkinson's disease patient carrying the digenic LRRK2 p.G2019S and GBA1 p.N409S mutations.

We describe an induced pluripotent stem cell (iPSC) line that was derived from fibroblasts obtained from a Parkinson's disease (PD) patient carrying the p.G2019S mutation in the LRRK2 gene and the p.N409S mutation in the GBA1 gene. iPSCs were generated via Sendai virus transduction of Yamanaka factors. The presence of GBA1 p.N409S and LRRK2 p.G2019S was confirmed by Sanger sequencing. The iPSCs express pluripotency markers, are capable of in vitro differentiation into the three germ layers and have a normal karyotype. The newly generated line will be used for in vitro PD modeling by investigating the role of each mutation in iPSC-derived dopaminergic neurons.

TARDBP mutations in a cohort of Italian patients with Parkinson's disease and atypical parkinsonisms.

Background: Aggregates of TAR DNA-binding protein of 43 kDa (TDP-43) represent the pathological hallmark of most amyotrophic lateral sclerosis (ALS) and of nearly 50% of frontotemporal dementia (FTD) cases but were also observed to occur as secondary neuropathology in the nervous tissue of patients with different neurodegenerative diseases, including Parkinson's disease (PD) and atypical parkinsonism. Mutations of TARDBP gene, mainly in exon 6 hotspot, have been reported to be causative of some forms of ALS and FTD, with clinical signs of parkinsonism observed in few mutation carriers. Methods: Direct DNA sequencing of TARDBP exon 6 was performed in a large Italian cohort of 735 patients affected by PD (354 familial and 381 sporadic) and 142 affected by atypical parkinsonism, including 39 corticobasal syndrome (CBS) and 103 progressive sopranuclear palsy (PSP). Sequencing data from 1710 healthy, ethnically matched controls were already available. Results: Four TARDBP missense variants (p.N267S, p. G294A, p.G295S, p.S393L) were identified in four patients with typical PD and in two individuals with atypical parkinsonism (1 CBS and 1 PSP). None of the detected mutations were found in healthy controls and only the variant p.N267S was previously described in association to idiopathic familial and sporadic PD and to CBS. Conclusion: In this study we provide further insight into the clinical phenotypic heterogeneity associated with TARDBP mutations, which expands beyond the classical ALS and FTD diseases to include also PD and atypical parkinsonism, although with a low mutational frequency, varying considerably in different Caucasian populations. In addition, our study extends the spectrum of TARDBP pathogenetic mutations found in familial and sporadic PD.

VPS13C-associated Parkinson's disease: Two novel cases and review of the literature.

VPS13C is a protein-coding gene involved in the regulation of mitochondrial function through the endolysosomal pathway in neurons. Homozygous and compound heterozygous VPS13C mutations are etiologically associated with early-onset Parkinson's disease (PD). Moreover, recent studies linked biallelic VPS13C mutations with the development of dementia with Lewy bodies (DLB). Neuropathological studies on two mutated subjects showed diffuse Lewy body disease. In this article, we report the clinical and genetic findings of two subjects affected by early-onset PD carrying three novel VPS13C mutations (i.e., one homozygous and one compound heterozygous), and review the previous literature on the genetic and clinical findings of VPS13C-mutated patients, contributing to the knowledge of this rare genetic alpha-synucleinopathy.

Genomewide Association Studies of LRRK2 Modifiers of Parkinson's Disease.

OBJECTIVE: The aim of this study was to search for genes/variants that modify the effect of LRRK2 mutations in terms of penetrance and age-at-onset of Parkinson's disease. METHODS: We performed the first genomewide association study of penetrance and age-at-onset of Parkinson's disease in LRRK2 mutation carriers (776 cases and 1,103 non-cases at their last evaluation). Cox proportional hazard models and linear mixed models were used to identify modifiers of penetrance and age-at-onset of LRRK2 mutations, respectively. We also investigated whether a polygenic risk score derived from a published genomewide association study of Parkinson's disease was able to explain variability in penetrance and age-at-onset in LRRK2 mutation carriers. RESULTS: A variant located in the intronic region of CORO1C on chromosome 12 (rs77395454; p value = 2.5E-08, beta = 1.27, SE = 0.23, risk allele: C) met genomewide significance for the penetrance model. Co-immunoprecipitation analyses of LRRK2 and CORO1C supported an interaction between these 2 proteins. A region on chromosome 3, within a previously reported linkage peak for Parkinson's disease susceptibility, showed suggestive associations in both models (penetrance top variant: p value = 1.1E-07; age-at-onset top variant: p value = 9.3E-07). A polygenic risk score derived from publicly available Parkinson's disease summary statistics was a significant predictor of penetrance, but not of age-at-onset. INTERPRETATION: This study suggests that variants within or near CORO1C may modify the penetrance of LRRK2 mutations. In addition, common Parkinson's disease associated variants collectively increase the penetrance of LRRK2 mutations. ANN NEUROL 2021;90:82-94.

TNF-α and α-synuclein fibrils differently regulate human astrocyte immune reactivity and impair mitochondrial respiration.

Here, we examine the cellular changes triggered by tumor necrosis factor alpha (TNF-α) and different alpha-synuclein (αSYN) species in astrocytes derived from induced pluripotent stem cells. Human astrocytes treated with TNF-α display a strong reactive pro-inflammatory phenotype with upregulation of pro-inflammatory gene networks, activation of the nuclear factor κB (NF-κB) pathway, and release of pro-inflammatory cytokines, whereas those treated with high-molecular-weight αSYN fibrils acquire a reactive antigen (cross)-presenting phenotype with upregulation of major histocompatibility complex (MHC) genes and increased human leukocyte antigen (HLA) molecules at the cell surface. Surprisingly, the cell surface location of MHC proteins is abrogated by larger F110 fibrillar polymorphs, despite the upregulation of MHC genes. Interestingly, TNF-α and αSYN fibrils compete to drive the astrocyte immune reactive response. The astrocyte immune responses are accompanied by an impaired mitochondrial respiration, which is exacerbated in Parkinson's disease (PD) astrocytes. Our data provide evidence for astrocytic involvement in PD pathogenesis and reveal their complex immune reactive responses to exogenous stressors.

Penetrance of Glucocerebrosidase (GBA) Mutations in Parkinson's Disease: A Kin Cohort Study.

BACKGROUND: Homozygous glucocerebrosidase mutations cause Gaucher disease, whereas heterozygous mutations are the most important genetic risk factor for Parkinson's disease (PD). The penetrance of heterozygous glucocerebrosidase mutations for PD is variable (10%-30%), depends on the population studied, and has only been assessed in Gaucher disease or familial PD. The aim of this study was to assess the penetrance of glucocerebrosidase mutations in PD in unselected PD patients. METHODS: The penetrance of glucocerebrosidase mutations was estimated using the kin-cohort method. RESULTS: Data on family history were available for 63 of 123 PD glucocerebrosidase mutation carriers, identified among 2843 unrelated consecutive PD patients. Three hundred eighty-one first-degree relatives were analyzed. The risk of developing PD was 10% at 60 years, 16% at 70 years, and 19% at 80 years. CONCLUSIONS: The estimated penetrance of glucocerebrosidase mutations in unselected PD patients is higher than that estimated in Gaucher disease cohorts and lower than that estimated in familial PD cohorts. © 2020 International Parkinson and Movement Disorder Society.

Nonsteroidal Anti-inflammatory Use and LRRK2 Parkinson's Disease Penetrance.

BACKGROUND: The penetrance of leucine rich repeat kinase 2 (LRRK2) mutations is incomplete and may be influenced by environmental and/or other genetic factors. Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to reduce inflammation and may lower Parkinson's disease (PD) risk, but their role in LRRK2-associated PD is unknown. OBJECTIVES: The objective of this study is to evaluate the association of regular NSAID use and LRRK2-associated PD. METHODS: Symptomatic ("LRRK2-PD") and asymptomatic ("LRRK2-non-PD") participants with LRRK2 G2019S, R1441X, or I2020T variants (definitely pathogenic variant carriers) or G2385R or R1628P variants (risk variant carriers) from 2 international cohorts provided information on regular ibuprofen and/or aspirin use (≥2 pills/week for ≥6 months) prior to the index date (diagnosis date for PD, interview date for non-PD). Multivariate logistic regression was used to evaluate the relationship between regular NSAID use and PD for any NSAID, separately for ibuprofen and aspirin in all carriers and separately in pathogenic and risk variant groups. RESULTS: A total of 259 LRRK2-PD and 318 LRRK2-non-PD participants were enrolled. Regular NSAID use was associated with reduced odds of PD in the overall cohort (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.21-0.57) and in both pathogenic and risk variant carriers (ORPathogenic , 0.38; 95% CI, 0.21-0.67 and ORRiskVariant , 0.19; 95% CI, 0.04-0.99). Similar associations were observed for ibuprofen and aspirin separately (ORIbuprofen , 0.19; 95% CI, 0.07-0.50 and ORAspirin , 0.51; 95% CI, 0.28-0.91). CONCLUSIONS: Regular NSAID use may be associated with reduced penetrance in LRRK2-associated PD. The LRRK2 protein is involved in inflammatory pathways and appears to be modulated by regular anti-inflammatory use. Longitudinal observational and interventional studies of NSAID exposure and LRRK2-PD are needed to confirm this association. © 2020 International Parkinson and Movement Disorder Society.

A human minisatellite hosts an alternative transcription start site for NPRL3 driving its expression in a repeat number-dependent manner.

Minisatellites, also called variable number of tandem repeats (VNTRs), are a class of repetitive elements that may affect gene expression at multiple levels and have been correlated to disease. Their identification and role as expression quantitative trait loci (eQTL) have been limited by their absence in comparative genomic hybridization and single nucleotide polymorphisms arrays. By taking advantage of cap analysis of gene expression (CAGE), we describe a new example of a minisatellite hosting a transcription start site (TSS) which expression is dependent on the repeat number. It is located in the third intron of the gene nitrogen permease regulator like protein 3 (NPRL3). NPRL3 is a component of the GAP activity toward rags 1 protein complex that inhibits mammalian target of rapamycin complex 1 (mTORC1) activity and it is found mutated in familial focal cortical dysplasia and familial focal epilepsy. CAGE tags represent an alternative TSS identifying TAGNPRL3 messenger RNAs (mRNAs). TAGNPRL3 is expressed in red blood cells both at mRNA and protein levels, it interacts with its protein partner NPRL2 and its overexpression inhibits cell proliferation. This study provides an example of a minisatellite that is both a TSS and an eQTL as well as identifies a new VNTR that may modify mTORC1 activity.

Generation of an induced pluripotent stem cell line (CSC-32) from a patient with Parkinson's disease carrying a heterozygous variation p.A53T in the SNCA gene.

Here, we describe the generation of an induced pluripotent stem cell (iPSC) line, from a male patient diagnosed with Parkinson's disease (PD). The patient carries a heterozygous variation p.A53T in the SNCA gene. Skin fibroblasts were reprogrammed using the non-integrating Sendai virus technology to deliver OCT3/4, SOX2, c-MYC and KLF4 factors. The generated iPSC line (CSC-32) preserved the mutation, displayed expression of common pluripotency markers, differentiated into derivatives of the three germ layers, and exhibited a normal karyotype. The clone CSC-32B is presented thereafter; it can be used to study the mechanisms underlying PD pathogenesis.

Cellular alterations identified in pluripotent stem cell-derived midbrain spheroids generated from a female patient with progressive external ophthalmoplegia and parkinsonism who carries a novel variation (p.Q811R) in the POLG1 gene.

Variations in the POLG1 gene encoding the catalytic subunit of the mitochondrial DNA polymerase gamma, have recently been associated with Parkinson's disease (PD), especially in patients diagnosed with progressive external ophthalmoplegia (PEO). However, the majority of the studies reporting this association mainly focused on the genetic identification of the variation in POLG1 in PD patient primary cells, and determination of mitochondrial DNA copy number, providing little information about the cellular alterations existing in patient brain cells, in particular dopaminergic neurons. Therefore, through the use of induced pluripotent stem cells (iPSCs), we assessed cellular alterations in novel p.Q811R POLG1 (POLG1Q811R) variant midbrain dopaminergic neuron-containing spheroids (MDNS) from a female patient who developed early-onset PD, and compared them to cultures derived from a healthy control of the same gender. Both POLG1 variant and control MDNS contained functional midbrain regionalized TH/FOXA2-positive dopaminergic neurons, capable of releasing dopamine. Western blot analysis identified the presence of high molecular weight oligomeric alpha-synuclein in POLG1Q811R MDNS compared to control cultures. In order to assess POLG1Q811R-related cellular alterations within the MDNS, we applied mass-spectrometry based quantitative proteomic analysis. In total, 6749 proteins were identified, with 61 significantly differentially expressed between POLG1Q811R and control samples. Pro- and anti-inflammatory signaling and pathways involved in energy metabolism were altered. Notably, increased glycolysis in POLG1Q811R MDNS was suggested by the increase in PFKM and LDHA levels and confirmed using functional analysis of glycolytic rate and oxygen consumption levels. Our results validate the use of iPSCs to assess cellular alterations in relation to PD pathogenesis, in a unique PD patient carrying a novel p.Q811R variation in POLG1, and identify several altered pathways that may be relevant to PD pathogenesis.

Generation of an induced pluripotent stem cell line (CSC-46) from a patient with Parkinson's disease carrying a novel p.R301C mutation in the GBA gene.

Mutations in the glucocerebrosidase (GBA) gene have been associated with the development of Parkinson's disease (PD). An induced pluripotent stem cell (iPSC) line was generated from a 60-year old patient diagnosed with PD and carrying a new mutation variant p.R301C in GBA. Using non-integrating Sendai virus-based technology, we utilized OCT3/4, SOX2, c-MYC and KLF4 transcription factors to reprogram skin fibroblasts into iPSCs. The generated iPSC line retained the mutation, displayed expression of common pluripotency markers, differentiated into the three germ layers, and exhibited normal karyotype. The iPSC line can be further used for studying PD pathogenesis.

Frequency of Loss of Function Variants in LRRK2 in Parkinson Disease.

Importance: Pathogenic variants in LRRK2 are a relatively common genetic cause of Parkinson disease (PD). Currently, the molecular mechanism underlying disease is unknown, and gain and loss of function (LOF) models of pathogenesis have been postulated. LRRK2 variants are reported to result in enhanced phosphorylation of substrates and increased cell death. However, the double knockout of Lrrk2 and its homologue Lrrk1 results in neurodegeneration in a mouse model, suggesting that disease may occur by LOF. Because LRRK2 inhibitors are currently in development as potential disease-modifying treatments in PD, it is critical to determine whether LOF variants in LRRK2 increase or decrease the risk of PD. Objective: To determine whether LRRK1 and LRRK2 LOF variants contribute to the risk of developing PD. Design, Setting, and Participants: To determine the prevailing mechanism of LRRK2-mediated disease in human populations, next-generation sequencing data from a large case-control cohort (>23 000 individuals) was analyzed for LOF variants in LRRK1 and LRRK2. Data were generated at 5 different sites and 5 different data sets, including cases with clinically diagnosed PD and neurologically normal control individuals. Data were collected from 2012 through 2017. Main Outcomes and Measures: Frequencies of LRRK1 and LRRK2 LOF variants present in the general population and compared between cases and controls. Results: Among 11 095 cases with PD and 12 615 controls, LRRK1 LOF variants were identified in 0.205% of cases and 0.139% of controls (odds ratio, 1.48; SE, 0.571; 95% CI, 0.45-4.44; P = .49) and LRRK2 LOF variants were found in 0.117% of cases and 0.087% of controls (odds ratio, 1.48; SE, 0.431; 95% CI, 0.63-3.50; P = .36). All association tests suggested lack of association between LRRK1 or LRRK2 variants and PD. Further analysis of lymphoblastoid cell lines from several heterozygous LOF variant carriers found that, as expected, LRRK2 protein levels are reduced by approximately half compared with wild-type alleles. Conclusions and Relevance: Together these findings indicate that haploinsufficiency of LRRK1 or LRRK2 is neither a cause of nor protective against PD. Furthermore, these results suggest that kinase inhibition or allele-specific targeting of mutant LRRK2 remain viable therapeutic strategies in PD.

Beyond 35 years of Parkinson's disease: a comprehensive clinical and instrumental assessment.

BACKGROUND: We sought to characterize the clinical, neuropsychological, electrophysiological, and neuroimaging features of Parkinson's disease (PD) after over 35 years since the onset of motor symptoms. METHODS: Five consecutively consenting PD patients treated with subthalamic nucleus deep brain stimulation (STN-DBS) were recruited in a cross-sectional study of motor (Unified PD Rating Scale section-III), non-motor (Non-Motor Symptoms Scale), autonomic (Scale for Outcome in PD-Autonomic), and neuropsychological features associated with the very advanced phase of PD. In addition, patients underwent neurophysiological (autonomic tests and nerve conduction studies) and neuroimaging (brain MRI, 123I-FP-CIT SPECT, and 123I-MIBG myocardial scintigraphy) studies, as well as a genetic analysis of 34 genes and single nucleotide polymorphisms associated with PD. RESULTS: There was a sustained motor response to L-dopa (range 14.4-35.6%), STN-DBS (23.3-38.4%), and L-dopa plus STN-DBS (37.8-63.0%). There were mild-to-moderate non-motor symptoms (range 19-83 on a scale of 0 to 360) and autonomic dysfunction (8-28 on a scale of 0-69). Two patients were demented, one had mild cognitive impairment, and two were cognitively preserved. Three patients had a sensory-axonal peripheral neuropathy and two a moderate-to-severe autonomic neuropathy. All cases showed a complete nigro-striatal dopaminergic denervation and a severe cardiovascular noradrenergic denervation. The brain MRI revealed only moderate frontal atrophy. The genetic tests were unremarkable. CONCLUSIONS: Even after more than 35 years of disease, L-dopa  and STN-DBS remain effective on PD cardinal symptoms. Although axial, autonomic, and neuropsychological features may become key determinants of disability, some patients maintain a satisfactory quality of life, without significant motor and non-motor impairment.

Multiple system atrophy and CAG repeat length: A genetic screening of polyglutamine disease genes in Italian patients.

Multiple system atrophy (MSA) is an adult onset, progressive, neurodegenerative disorder of unknown etiology characterized by autonomic dysfunction, parkinsonism (MSA-P) and cerebellar ataxia (MSA-C). The phenotypic spectrum may present overlapping features with other neurodegenerative diseases, particularly the autosomal dominant inherited polyglutamine disorders. To investigate the possible contribution of CAG expansions in the MSA phenotype, we analyzed the triplet repeat length in the autosomal dominant causative genes for spinocerebellar ataxia (SCA) type 1, 2, 3, 6, 7, 17, dentatorubral-pallidoluysian atrophy (DRPLA) and Huntington disease (HD) in a cohort of 246 Italian MSA patients. As comparison, 223 controls were also analyzed. The alleles were classified on the basis of CAG repeat length as "normal", "intermediate" or "expanded" according to literature. The MSA patients (101 men/145 women) had a mean age at onset of 58 years and a mean age at genetic testing of 63 years. MSA-C patients had significantly younger age at onset and at examination in comparison to MSA-P (p < 0.0001). We identified a SCA1 intermediate allele in a MSA-C subject (36 CAG), a SCA2 intermediate allele in a MSA-P patient (31 CAG), and a pathologically expanded SCA2 allele (36 CAG) in a patient initially misdiagnosed as MSA-C. No intermediate or expanded SCA alleles were detected in controls. The distribution of CAG repeat length was similar among groups except for SCA1 gene that showed a higher percentage of longer normal alleles in MSA-C as compared to MSA-P and controls (p < 0.0001). This study supports the utility of polyQ genetic testing in the differential diagnosis of MSA, and may suggest a possible role of SCA1 repeat length as risk factor for MSA-C. SCA1 and SCA2 genetic screening is recommended in MSA Italian patients.

The Length of SNCA Rep1 Microsatellite May Influence Cognitive Evolution in Parkinson's Disease.

BACKGROUND: Alpha-synuclein is a constituent of Lewy bodies and mutations of its gene cause familial Parkinson's disease (PD). A previous study showed that a variant of the alpha-synuclein gene (SNCA), namely the 263 bp allele of Rep1 was associated with faster motor progression in PD. On the contrary, a recent report failed to detect a detrimental effect of Rep1 263 on both motor and cognitive outcomes in PD. Aim of this study was to evaluate the influence of the Rep1 variants on disease progression in PD patients. METHODS: We recruited and genotyped for SNCA Rep1 426 PD patients with age at onset ≥40 years and disease duration ≥4 years. We then analyzed frequency and time of occurrence of wearing-off, dyskinesia, freezing of gait, visual hallucinations, and dementia using a multivariate Cox's proportional hazards regression model. RESULTS: SNCA Rep1 263 carriers showed significantly increased risk of both dementia (HR = 3.03) and visual hallucinations (HR = 2.69) compared to 263 non-carriers. Risk of motor complications did not differ in the two groups. CONCLUSION: SNCA Rep1 263 allele is associated with a worse cognitive outcome in PD.

The LRRK2 Variant E193K Prevents Mitochondrial Fission Upon MPP+ Treatment by Altering LRRK2 Binding to DRP1.

Mutations in leucine-rich repeat kinase 2 gene (LRRK2) are associated with familial and sporadic Parkinson's disease (PD). LRRK2 is a complex protein that consists of multiple domains, including 13 putative armadillo-type repeats at the N-terminus. In this study, we analyzed the functional and molecular consequences of a novel variant, E193K, identified in an Italian family. E193K substitution does not influence LRRK2 kinase activity. Instead it affects LRRK2 biochemical properties, such as phosphorylation at Ser935 and affinity for 14-3-3ε. Primary fibroblasts obtained from an E193K carrier demonstrated increased cellular toxicity and abnormal mitochondrial fission upon 1-methyl-4-phenylpyridinium treatment. We found that E193K alters LRRK2 binding to DRP1, a crucial mediator of mitochondrial fission. Our data support a role for LRRK2 as a scaffolding protein influencing mitochondrial fission.

Insufficient evidence for pathogenicity of SNCA His50Gln (H50Q) in Parkinson's disease.

SNCA missense mutations are a rare cause of autosomal dominant Parkinson's disease (PD). To date, 6 missense mutations in SNCA have been nominated as causal. Here, we assess the frequency of these 6 mutations in public population databases and PD case-control data sets to determine their true pathogenicity. We found that 1 of the 6 reported SNCA mutations, His50Gln, was consistently identified in large population databases, and no enrichment was evident in PD cases compared to controls. These results suggest that His50Gln is probably not a pathogenic variant. This information is important to provide counseling for His50Gln carriers and has implications for the interpretation of His50Gln α-synuclein functional investigations.

Generation of an induced pluripotent stem cell line (CSC-41) from a Parkinson's disease patient carrying a p.G2019S mutation in the LRRK2 gene.

The leucine-rich repeat kinase 2 (LRRK2) p.G2019S mutation is the most common genetic cause of Parkinson's disease (PD). An induced pluripotent stem cell (iPSC) line CSC-41 was generated from a 75-year old patient diagnosed with PD caused by a p.G2019S mutation in LRRK2. Skin fibroblasts were reprogrammed using a non-integrating Sendai virus-based technology to deliver OCT3/4, SOX2, c-MYC and KLF4 transcription factors. The generated iPSC line exhibits expression of common pluripotency markers, differentiates into the three germ layers and has a normal karyotype. The iPSC line can be used to explore the association between LRRK2 mutation and PD.

Generation of a human induced pluripotent stem cell line (CSC-42) from a patient with sporadic form of Parkinson's disease.

Skin fibroblasts were collected from a 44-year-old patient with sporadic case of Parkinson's disease (PD). The non-integrating Sendai virus vector encoding OCT3/4, SOX2, c-MYC and KLF4 was used to reprogram fibroblasts into induced pluripotent stem cells (iPSCs). Generated iPSCs had normal karyotypes, expressed common stem cell markers, and were capable of differentiating into all three germ layers. Generated line could be used for PD modeling to understand the mechanisms that influence the disorder.

Generation of an integration-free induced pluripotent stem cell line (CSC-43) from a patient with sporadic Parkinson's disease.

An induced pluripotent stem cell (iPSC) line was generated from a 36-year-old patient with sporadic Parkinson's disease (PD). Skin fibroblasts were reprogrammed using the non-integrating Sendai virus technology to deliver OCT3/4, SOX2, c-MYC and KLF4 factors. The generated cell line (CSC-43) exhibits expression of common pluripotency markers, in vitro differentiation into three germ layers and normal karyotype. This iPSC line can be used to study the mechanisms underlying the development of PD.