Are rare heterozygous SYNJ1 variants associated with Parkinson's disease?

Previous studies have established that rare biallelic SYNJ1 mutations cause autosomal recessive parkinsonism and Parkinson's disease (PD). We analyzed 8165 PD cases, 818 early-onset-PD (EOPD, < 50 years) and 70,363 controls. Burden meta-analysis revealed an association between rare nonsynonymous variants and variants with high Combined Annotation-Dependent Depletion score (> 20) in the Sac1 SYNJ1 domain and PD (Pfdr = 0.040). A meta-analysis of EOPD patients demonstrated an association between all rare heterozygous SYNJ1 variants and PD (Pfdr = 0.029).

Crizanlizumab for retinal vasculopathy with cerebral leukoencephalopathy in a phase II clinical study.

BackgroundRetinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare, autosomal dominant, universally fatal disease without effective treatment options. This study explores the safety and preliminary efficacy of crizanlizumab, a humanized monoclonal antibody against P-selectin approved for the prevention of sickle cell crises, in slowing retinal nonperfusion and preserving vision in patients with RVCL-S.METHODSEleven patients with RVCL-S with confirmed exonuclease 3 prime repair exonuclease 1 (TREX1) mutations received monthly crizanlizumab infusions over 2 years. The study measured the nonperfusion index within 3 retinal zones and the total retina with fluorescein angiography, visual acuity, intraocular pressure (IOP), and optical coherence tomography central subfield thickness (CST) at baseline, 1 year, and 2 years. A mixed repeated-measures analysis was performed to assess the progression rates and changes from baseline.RESULTSEleven participants received crizanlizumab infusions. All of the participants tolerated crizanlizumab well, with 8 of 11 (72.7%) reporting mild adverse effects such as nausea, fatigue, and gastrointestinal symptoms. The change in total retinal nonperfusion was 7.22% [4.47, 9.97] in year 1 and -0.69% [-4.06, 2.68] in year 2 (P < 0.001). In the mid periphery, the change in nonperfusion was 10.6% [5.1, 16.1] in year 1 and -0.68% [-3.98, 5.35] in year 2 (P < 0.01), demonstrating a reduction in progression of nonperfusion in the second year of treatment. Visual acuity, IOP, and CST remained stable.CONCLUSIONCrizanlizumab has an acceptable safety profile. These results show promising potential for examining crizanlizumab in larger studies of RVCL-S and similar small-vessel diseases and for using the retina as a biomarker for systemic disease.Trial registrationClinicalTrials.gov NCT04611880.FUNDINGThe Clayco Foundation; DeNardo Education and Research Foundation Grant; Jeffrey T. Fort Innovation Fund; Siteman Retina Research Fund; unrestricted grant from Research to Prevent Blindness Inc.; National Heart,Lung, and Blood Institute (NHLBI), NIH (R01HL129241); National Institute of Neurological Disorders and Stroke (NINDS), NIH (RF1NS116565).

A combined radio-immunotherapy regimen eradicates late-stage tumors in mice.

Background: The majority of experimental approaches for cancer immunotherapy are tested against relatively small tumors in tumor-bearing mice, because in most cases advanced cancers are resistant to the treatments. In this study, we asked if even late-stage mouse tumors can be eradicated by a rationally designed combined radio-immunotherapy (CRI) regimen. Methods: CRI consisted of local radiotherapy, intratumoral IL-12, slow-release systemic IL-2 and anti- CTLA-4 antibody. Therapeutic effects of CRI against several weakly immunogenic and immunogenic mouse tumors including B78 melanoma, MC38 and CT26 colon carcinomas and 9464D neuroblastoma were evaluated. Immune cell depletion and flow cytometric analysis were performed to determine the mechanisms of the antitumor effects. Results: Tumors with volumes of 2,000 mm3 or larger were eradicated by CRI. Flow analyses of the tumors revealed reduction of T regulatory (Treg) cells and increase of CD8/Treg ratios following CRI. Rapid shrinkage of the treated tumors did not require T cells, whereas T cells were involved in the systemic effect against the distant tumors. Cured mice developed immunological memory. Conclusions: These findings underscore that rationally designed combination immunotherapy regimens can be effective even against large, late-stage tumors.

Are rare heterozygous SYNJ1 variants associated with Parkinson's disease?

Previous studies have suggested that rare biallelic SYNJ1 mutations may cause autosomal recessive parkinsonism and Parkinson's disease (PD). Our study explored the impact of rare SYNJ1 variants in non-familial settings, including 8,165 PD cases, 818 early-onset PD (EOPD, <50 years) and 70,363 controls. Burden meta-analysis using optimized sequence Kernel association test (SKAT-O) revealed an association between rare nonsynonymous variants in the Sac1 SYNJ1 domain and PD (Pfdr=0.040). Additionally, a meta-analysis focusing on patients with EOPD demonstrated an association between all rare SYNJ1 variants and PD (Pfdr=0.029). Rare SYNJ1 variants may be associated with sporadic PD, and more specifically with EOPD.

The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons.

Background: Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified. Methods: Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils. Results: We first identified specific non-coding variants in CTSB that drive the association with PD and are linked to changes in brain CTSB expression levels. Using iPSC-derived dopaminergic neurons we then find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1) activity, and leads to an accumulation of lysosomal content. Moreover, in cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. Similarly, in midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition or knockout potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein. Conclusions: The results of our genetic and functional studies indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

Rare-variant and polygenic analyses of amyotrophic lateral sclerosis in the French-Canadian genome.

PURPOSE: The genetic etiology of amyotrophic lateral sclerosis (ALS) includes few rare, large-effect variants and potentially many common, small-effect variants per case. The genetic risk liability for ALS might require a threshold comprised of a certain amount of variants. Here, we tested the degree to which risk for ALS was affected by rare variants in ALS genes, polygenic risk score, or both. METHODS: 335 ALS cases and 356 controls from Québec, Canada were concurrently tested by microarray genotyping and targeted sequencing of ALS genes known at the time of study inception. ALS genome-wide association studies summary statistics were used to estimate an ALS polygenic risk score (PRS). Cases and controls were subdivided into rare-variant heterozygotes and non-heterozygotes. RESULTS: Risk for ALS was significantly associated with PRS and rare variants independently in a logistic regression model. Although ALS PRS predicted a small amount of ALS risk overall, the effect was most pronounced between ALS cases and controls that were not heterozygous for a rare variant in the ALS genes surveyed. CONCLUSION: Both PRS and rare variants in ALS genes impact risk for ALS. PRS for ALS is most informative when rare variants are not observed in ALS genes.

The Parkinson's disease risk gene cathepsin B promotes fibrillar alpha-synuclein clearance, lysosomal function and glucocerebrosidase activity in dopaminergic neurons.

Variants in the CTSB gene encoding the lysosomal hydrolase cathepsin B (catB) are associated with increased risk of Parkinson's disease (PD). However, neither the specific CTSB variants driving these associations nor the functional pathways that link catB to PD pathogenesis have been characterized. CatB activity contributes to lysosomal protein degradation and regulates signaling processes involved in autophagy and lysosome biogenesis. Previous in vitro studies have found that catB can cleave monomeric and fibrillar alpha-synuclein, a key protein involved in the pathogenesis of PD that accumulates in the brains of PD patients. However, truncated synuclein isoforms generated by catB cleavage have an increased propensity to aggregate. Thus, catB activity could potentially contribute to lysosomal degradation and clearance of pathogenic alpha synuclein from the cell, but also has the potential of enhancing synuclein pathology by generating aggregation-prone truncations. Therefore, the mechanisms linking catB to PD pathophysiology remain to be clarified. Here, we conducted genetic analyses of the association between common and rare CTSB variants and risk of PD. We then used genetic and pharmacological approaches to manipulate catB expression and function in cell lines and induced pluripotent stem cell-derived dopaminergic neurons and assessed lysosomal activity and the handling of aggregated synuclein fibrils. We find that catB inhibition impairs autophagy, reduces glucocerebrosidase (encoded by GBA1) activity, and leads to an accumulation of lysosomal content. In cell lines, reduction of CTSB gene expression impairs the degradation of pre-formed alpha-synuclein fibrils, whereas CTSB gene activation enhances fibril clearance. In midbrain organoids and dopaminergic neurons treated with alpha-synuclein fibrils, catB inhibition potentiates the formation of inclusions which stain positively for phosphorylated alpha-synuclein. These results indicate that the reduction of catB function negatively impacts lysosomal pathways associated with PD pathogenesis, while conversely catB activation could promote the clearance of pathogenic alpha-synuclein.

Generation of Novel Immunocompetent Mouse Cell Lines to Model Experimental Metastasis of High-Risk Neuroblastoma.

NB, being a highly metastatic cancer, is one of the leading causes of cancer-related deaths in children. Increased disease recurrence and clinical resistance in patients with metastatic high-risk NBs (HR-NBs) result in poor outcomes and lower overall survival. However, the paucity of appropriate in vivo models for HR-NB metastasis has limited investigations into the underlying biology of HR-NB metastasis. This study was designed to address this limitation and develop suitable immunocompetent models for HR-NB metastasis. Here, we developed several highly metastatic immunocompetent murine HR-NB cell lines. Our newly developed cell lines show 100% efficiency in modeling experimental metastasis in C57BL6 mice and feature metastasis to the sites frequently observed in humans with HR-NB (liver and bone). In vivo validation demonstrated their specifically gained metastatic phenotype. The in vitro characterization of the cell lines showed increased cell invasion, acquired anchorage-independent growth ability, and resistance to MHC-I induction upon IFN-γ treatment. Furthermore, RNA-seq analysis of the newly developed cells identified a differentially regulated gene signature and an enrichment of processes consistent with their acquired metastatic phenotype, including extracellular matrix remodeling, angiogenesis, cell migration, and chemotaxis. The presented newly developed cell lines are, thus, suitable and promising tools for HR-NB metastasis and microenvironment studies in an immunocompetent system.

HLA in isolated REM sleep behavior disorder and Lewy body dementia.

Synucleinopathies-related disorders such as Lewy body dementia (LBD) and isolated/idiopathic REM sleep behavior disorder (iRBD) have been associated with neuroinflammation. In this study, we examined whether the human leukocyte antigen (HLA) locus plays a role in iRBD and LBD. In iRBD, HLA-DRB1*11:01 was the only allele passing FDR correction (OR = 1.57, 95% CI = 1.27-1.93, p = 2.70e-05). We also discovered associations between iRBD and HLA-DRB1 70D (OR = 1.26, 95%CI = 1.12-1.41, p = 8.76e-05), 70Q (OR = 0.81, 95%CI = 0.72-0.91, p = 3.65e-04) and 71R (OR = 1.21, 95%CI = 1.08-1.35, p = 1.35e-03). Position 71 (pomnibus = 0.00102) and 70 (pomnibus = 0.00125) were associated with iRBD. Our results suggest that the HLA locus may have different roles across synucleinopathies.

Association of Rare Variants in ARSA with Parkinson's Disease.

BACKGROUND: Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA remains unclear. OBJECTIVES: To study rare ARSA variants in PD. METHODS: To study rare ARSA variants (minor allele frequency < 0.01) in PD, we performed burden analyses in six independent cohorts with 5801 PD patients and 20,475 controls, followed by a meta-analysis. RESULTS: We found evidence for associations between functional ARSA variants and PD in four cohorts (P ≤ 0.05 in each) and in the meta-analysis (P = 0.042). We also found an association between loss-of-function variants and PD in the United Kingdom Biobank cohort (P = 0.005) and in the meta-analysis (P = 0.049). These results should be interpreted with caution as no association survived multiple comparisons correction. Additionally, we describe two families with potential co-segregation of ARSA p.E382K and PD. CONCLUSIONS: Rare functional and loss-of-function ARSA variants may be associated with PD. Further replications in large case-control/familial cohorts are required. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

NPC1 variants are not associated with Parkinson's disease, REM-sleep behavior disorder or dementia with Lewy bodies in European cohorts.

NPC1 encodes a lysosomal protein involved in cholesterol transport. Biallelic mutations in this gene may lead to Niemann-Pick disease type C (NPC), a lysosomal storage disorder. The role of NPC1 in alpha synucleinopathies is still unclear, as different genetic, clinical, and pathological studies have reported contradictory results. This study aimed to evaluate the association of NPC1 variants with the synucleinopathies Parkinson's disease (PD), dementia with Lewy bodies (DLB), and rapid eye movement-sleep behavior disorder (RBD). We analyzed common and rare variants from 3 cohorts of European descent: 1084 RBD cases and 2945 controls, 2852 PD cases and 1686 controls, and 2610 DLB cases and 1920 controls. Logistic regression models were used to assess common variants while optimal sequence Kernel association tests were used to assess rare variants, both adjusted for sex, age, and principal components. No variants were associated with any of the synucleinopathies, supporting that common and rare NPC1 variants do not play an important role in alpha synucleinopathies.

Factors impacting the efficacy of the in-situ vaccine with CpG and OX40 agonist.

BACKGROUND: The in-situ vaccine using CpG oligodeoxynucleotide combined with OX40 agonist antibody (CpG + OX40) has been shown to be an effective therapy activating an anti-tumor T cell response in certain settings. The roles of tumor volume, tumor model, and the addition of checkpoint blockade in the efficacy of CpG + OX40 in-situ vaccination remains unknown. METHODS: Mice bearing flank tumors (B78 melanoma or A20 lymphoma) were treated with combinations of CpG, OX40, and anti-CTLA-4. Tumor growth and survival were monitored. In vivo T cell depletion, tumor cell phenotype, and tumor infiltrating lymphocyte (TIL) studies were performed. Tumor cell sensitivity to CpG and macrophages were evaluated in vitro. RESULTS: As tumor volumes increased in the B78 (one-tumor) and A20 (one-tumor or two-tumor) models, the anti-tumor efficacy of the in-situ vaccine decreased. In vitro, CpG had a direct effect on A20 proliferation and phenotype and an indirect effect on B78 proliferation via macrophage activation. As A20 tumors progressed in vivo, tumor cell phenotype changed, and T cells became more involved in the local CpG + OX40 mediated anti-tumor response. In mice with larger tumors that were poorly responsive to CpG + OX40, the addition of anti-CTLA-4 enhanced the anti-tumor efficacy in the A20 but not B78 models. CONCLUSIONS: Increased tumor volume negatively impacts the anti-tumor capability of CpG + OX40 in-situ vaccine. The addition of checkpoint blockade augmented the efficacy of CpG + OX40 in the A20 but not B78 model. These results highlight the importance of considering multiple preclinical model conditions when assessing the efficacy of cancer immunotherapy regimens and their translation to clinical testing.

Genetic analyses of DNA repair pathway associated genes implicate new candidate cancer predisposing genes in ancestrally defined ovarian cancer cases.

Not all familial ovarian cancer (OC) cases are explained by pathogenic germline variants in known risk genes. A candidate gene approach involving DNA repair pathway genes was applied to identify rare recurring pathogenic variants in familial OC cases not associated with known OC risk genes from a population exhibiting genetic drift. Whole exome sequencing (WES) data of 15 OC cases from 13 families tested negative for pathogenic variants in known OC risk genes were investigated for candidate variants in 468 DNA repair pathway genes. Filtering and prioritization criteria were applied to WES data to select top candidates for further analyses. Candidates were genotyped in ancestry defined study groups of 214 familial and 998 sporadic OC or breast cancer (BC) cases and 1025 population-matched controls and screened for additional carriers in 605 population-matched OC cases. The candidate genes were also analyzed in WES data from 937 familial or sporadic OC cases of diverse ancestries. Top candidate variants in ERCC5, EXO1, FANCC, NEIL1 and NTHL1 were identified in 5/13 (39%) OC families. Collectively, candidate variants were identified in 7/435 (1.6%) sporadic OC cases and 1/566 (0.2%) sporadic BC cases versus 1/1025 (0.1%) controls. Additional carriers were identified in 6/605 (0.9%) OC cases. Tumour DNA from ERCC5, NEIL1 and NTHL1 variant carriers exhibited loss of the wild-type allele. Carriers of various candidate variants in these genes were identified in 31/937 (3.3%) OC cases of diverse ancestries versus 0-0.004% in cancer-free controls. The strategy of applying a candidate gene approach in a population exhibiting genetic drift identified new candidate OC predisposition variants in DNA repair pathway genes.

Association of rare variants in ARSA with Parkinson's disease.

Background: Several lysosomal genes are associated with Parkinson's disease (PD), yet the association between PD and ARSA , which encodes for the enzyme arylsulfatase A, remains controversial. Objectives: To evaluate the association between rare ARSA variants and PD. Methods: To study possible association of rare variants (minor allele frequency<0.01) in ARSA with PD, we performed burden analyses in six independent cohorts with a total of 5,801 PD patients and 20,475 controls, using optimized sequence Kernel association test (SKAT-O), followed by a meta-analysis. Results: We found evidence for an association between functional ARSA variants and PD in four independent cohorts (P≤0.05 in each) and in the meta-analysis (P=0.042). We also found an association between loss-of-function variants and PD in the UKBB cohort (P=0.005) and in the meta-analysis (P=0.049). However, despite replicating in four independent cohorts, these results should be interpreted with caution as no association survived correction for multiple comparisons. Additionally, we describe two families with potential co-segregation of the ARSA variant p.E384K and PD. Conclusions: Rare functional and loss-of-function ARSA variants may be associated with PD. Further replication in large case-control cohorts and in familial studies is required to confirm these associations.

HLA in isolated REM sleep behavior disorder and Lewy body dementia.

Background and Objectives: Isolated/idiopathic REM sleep behavior disorder (iRBD) and Lewy body dementia (LBD) are synucleinopathies that have partial genetic overlap with Parkinson's disease (PD). Previous studies have shown that neuroinflammation plays a substantial role in these disorders. In PD, specific residues of the human leukocyte antigen ( HLA ) were suggested to be associated with a protective effect. This study examined whether the HLA locus plays a similar role in iRBD, LBD and PD. Methods: We performed HLA imputation on iRBD genotyping data (1,072 patients and 9,505 controls) and LBD whole-genome sequencing (2,604 patients and 4,032 controls) using the multi-ethnic HLA reference panel v2 from the Michigan Imputation Server. Using logistic regression, we tested the association of HLA alleles, amino acids and haplotypes with disease susceptibility. We included age, sex and the top 10 principal components as covariates. We also performed an omnibus test to examine which HLA residue positions explain the most variance. Results: In iRBD, HLA-DRB1 *11:01 was the only allele passing FDR correction (OR=1.57, 95% CI=1.27-1.93, p =2.70e-05). We also discovered associations between iRBD and HLA-DRB1 70D (OR=1.26, 95%CI=1.12-1.41, p =8.76e-05), 70Q (OR=0.81, 95% CI=0.72-0.91, p =3.65e-04) and 71R (OR=1.21, 95% CI=1.08-1.35, p =1.35e-03). In HLA-DRB1 , position 71 ( p omnibus =0.00102) and 70 ( p omnibus =0.00125) were associated with iRBD. We found no association in LBD. Discussion: This study identified an association between HLA-DRB1 11:01 and iRBD, distinct from the previously reported association in PD. Therefore, the HLA locus may play different roles across synucleinopathies. Additional studies are required better to understand HLA's role in iRBD and LBD.

GALC variants affect galactosylceramidase enzymatic activity and risk of Parkinson's disease.

The association between glucocerebrosidase, encoded by GBA, and Parkinson's disease (PD) highlights the role of the lysosome in PD pathogenesis. Genome-wide association studies in PD have revealed multiple associated loci, including the GALC locus on chromosome 14. GALC encodes the lysosomal enzyme galactosylceramidase, which plays a pivotal role in the glycosphingolipid metabolism pathway. It is still unclear whether GALC is the gene driving the association in the chromosome 14 locus and, if so, by which mechanism. We first aimed to examine whether variants in the GALC locus and across the genome are associated with galactosylceramidase activity. We performed a genome-wide association study in two independent cohorts from (i) Columbia University; and (ii) the Parkinson's Progression Markers Initiative study, followed by a meta-analysis with a total of 976 PD patients and 478 controls with available data on galactosylceramidase activity. We further analysed the effects of common GALC variants on expression and galactosylceramidase activity using genomic colocalization methods. Mendelian randomization was used to study whether galactosylceramidase activity may be causal in PD. To study the role of rare GALC variants, we analysed sequencing data from 5028 PD patients and 5422 controls. Additionally, we studied the functional impact of GALC knockout on alpha-synuclein accumulation and on glucocerebrosidase activity in neuronal cell models and performed in silico structural analysis of common GALC variants associated with altered galactosylceramidase activity. The top hit in PD genome-wide association study in the GALC locus, rs979812, is associated with increased galactosylceramidase activity (b = 1.2; SE = 0.06; P = 5.10 × 10-95). No other variants outside the GALC locus were associated with galactosylceramidase activity. Colocalization analysis demonstrated that rs979812 was also associated with increased galactosylceramidase expression. Mendelian randomization suggested that increased galactosylceramidase activity may be causally associated with PD (b = 0.025, SE = 0.007, P = 0.0008). We did not find an association between rare GALC variants and PD. GALC knockout using CRISPR-Cas9 did not lead to alpha-synuclein accumulation, further supporting that increased rather than reduced galactosylceramidase levels may be associated with PD. The structural analysis demonstrated that the common variant p.I562T may lead to improper maturation of galactosylceramidase affecting its activity. Our results nominate GALC as the gene associated with PD in this locus and suggest that the association of variants in the GALC locus may be driven by their effect of increasing galactosylceramidase expression and activity. Whether altering galactosylceramidase activity could be considered as a therapeutic target should be further studied.

Investigation of the causal relationship between ALS and autoimmune disorders: a Mendelian randomization study.

BACKGROUND: Epidemiological studies have reported an association between amyotrophic lateral sclerosis (ALS) and different autoimmune disorders. This study aims to explore the causal relationship between autoimmune disorders and ALS using Mendelian randomization (MR). METHODS: To test the genetically predicted effects of liability towards immune-related outcomes on ALS risk, we used summary statistics from the largest European genome-wide association studies (GWAS) for these disorders in a two-sample MR setting. To do this, we extracted single nucleotide polymorphisms (SNPs) from the GWAS, which strongly associated with the 12 traits, and queried their effects in a large European ALS GWAS (27,265 cases and 110,881 controls). To avoid bias in our MR instruments related to the complex linkage disequilibrium structure of the human leukocyte antigen (HLA) region, we excluded SNPs within this region from the analyses. We computed inverse-variance weighted (IVW) MR estimates and undertook sensitivity analyses using MR methods robust to horizontal pleiotropy. We also performed a reverse MR analysis testing the causal effects of ALS on the above autoimmune traits. RESULTS: After applying Bonferroni correction for multiple testing, our MR analyses showed that the liability to autoimmune disorders does not affect ALS risk. Our reverse MR analysis also did not support the effects of liability to ALS on other autoimmune disorders. The results of the main IVW MR analyses were generally supported by our sensitivity MR analyses. The variance in the exposures explained by the sets of SNPs used as MR instruments ranged from 8.1 × 10-4 to 0.31. Our MR study was well-powered to detect effects as small as an odds ratio (OR) of 1.045 for ALS in the main MR and as small as an OR of 1.32 in the reverse MR. CONCLUSION: Our MR study does not support a relationship between liability to autoimmune disorders and ALS risk in the European population. The associations observed in epidemiological studies could be partly attributed to shared biology or environmental confounders.

Gene-based burden analysis of damaging private variants in PRKN, PARK7 and PINK1 in Parkinson's disease cohorts of European descent.

Recessive mutations in PRKN, PARK7, and PINK1 are established causes of early-onset Parkinson's disease (EOPD). Previous studies have interrogated the role of heterozygous variants in these genes but mainly focused on rare (minor allele frequency [MAF] <1%) damaging variants or established mutations. Here, we assessed heterozygous private PRKN, PARK7 and PINK1 variants in PD risk in four large-scale PD case-control datasets by performing gene-wise burden analyses using sequencing data totaling 5,829 PD cases and 7,221 controls, and summary allele counts from 9,501 PD cases and 48,207 controls. Results showed no significant burden in all three genes after meta-analyses. Burden in EOPD (age at onset <50 years) and late-onset PD (≥50 years) remained nonsignificant. In summary, we found no evidence to support the association of the excess burden of heterozygous private variants in PRKN, PARK7, and PINK1 with PD risk in the European population. Larger, more diverse cohorts are needed to accurately determine their role in PD.

Questioning the Association of the STMN2 Dinucleotide Repeat With Amyotrophic Lateral Sclerosis.

Objectives: Recently, the number of dinucleotide CA repeats in an intron of the STMN2 gene was reported to be associated with an increased risk for amyotrophic lateral sclerosis (ALS). Therefore, we sought to replicate this observation in an independent group of ALS patients and a much larger control group. Methods: Here, we used whole-genome sequencing and tested the STMN2 CA repeat in a case-control cohort of the European genetic background and in genomes from various populations in the gnomAD cohort to attempt to replicate this proposed association. Results: We find that repeats well above the previously reported pathogenic threshold of 19 are commonly observed in unaffected individuals across different populations. Furthermore, we did not observe an association between longer STMN2 CA repeats and ALS phenotype. Discussion: In summary, our results do not support a role of STMN2 CA repeats toward ALS risk. As TDP-43 aggregation is central to ALS pathogenesis, lowered expression of STMN2 could be used as a biomarker for ALS. Therefore, a variant associated both with the risk for ALS and the level of STMN2 expression would be clinically useful. However, for a variant to be actionable, it must be strongly replicated in independent cohorts and exceed the rigorous statistical thresholds applied.