Publications by authors named "Owen A Ross"

315 Publications

Copy Number Variation in Parkinson's Disease: An Update from Sub-Saharan Africa.

Mov Disord 2021 Jul 6. Epub 2021 Jul 6.

Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.

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http://dx.doi.org/10.1002/mds.28710DOI Listing
July 2021

A molecular pathology, neurobiology, biochemical, genetic and neuroimaging study of progressive apraxia of speech.

Nat Commun 2021 06 8;12(1):3452. Epub 2021 Jun 8.

Department of Radiology, Mayo Clinic, Rochester, MN, USA.

Progressive apraxia of speech is a neurodegenerative syndrome affecting spoken communication. Molecular pathology, biochemistry, genetics, and longitudinal imaging were investigated in 32 autopsy-confirmed patients with progressive apraxia of speech who were followed over 10 years. Corticobasal degeneration and progressive supranuclear palsy (4R-tauopathies) were the most common underlying pathologies. Perceptually distinct speech characteristics, combined with age-at-onset, predicted specific 4R-tauopathy; phonetic subtype and younger age predicted corticobasal degeneration, and prosodic subtype and older age predicted progressive supranuclear palsy. Phonetic and prosodic subtypes showed differing relationships within the cortico-striato-pallido-nigro-luysial network. Biochemical analysis revealed no distinct differences in aggregated 4R-tau while tau H1 haplotype frequency (69%) was lower compared to 1000+ autopsy-confirmed 4R-tauopathies. Corticobasal degeneration patients had faster rates of decline, greater cortical degeneration, and shorter illness duration than progressive supranuclear palsy. These findings help define the pathobiology of progressive apraxia of speech and may have consequences for development of 4R-tau targeting treatment.
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http://dx.doi.org/10.1038/s41467-021-23687-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8187627PMC
June 2021

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

Ann Neurol 2021 Jul 17;90(1):76-88. Epub 2021 May 17.

23andMe, Inc., Sunnyvale, CA.

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.
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http://dx.doi.org/10.1002/ana.26094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252519PMC
July 2021

Dancing Feet Dyskinesia in a Patient with GBA-PD.

J Mov Disord 2021 05 3. Epub 2021 May 3.

The Dublin Neurological Institute at the Mater Misericordiae University Hospital, Dublin, Ireland.

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http://dx.doi.org/10.14802/jmd.20169DOI Listing
May 2021

Transcriptomic analysis to identify genes associated with selective hippocampal vulnerability in Alzheimer's disease.

Nat Commun 2021 04 19;12(1):2311. Epub 2021 Apr 19.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.

Selective vulnerability of different brain regions is seen in many neurodegenerative disorders. The hippocampus and cortex are selectively vulnerable in Alzheimer's disease (AD), however the degree of involvement of the different brain regions differs among patients. We classified corticolimbic patterns of neurofibrillary tangles in postmortem tissue to capture extreme and representative phenotypes. We combined bulk RNA sequencing with digital pathology to examine hippocampal vulnerability in AD. We identified hippocampal gene expression changes associated with hippocampal vulnerability and used machine learning to identify genes that were associated with AD neuropathology, including SERPINA5, RYBP, SLC38A2, FEM1B, and PYDC1. Further histologic and biochemical analyses suggested SERPINA5 expression is associated with tau expression in the brain. Our study highlights the importance of embracing heterogeneity of the human brain in disease to identify disease-relevant gene expression.
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http://dx.doi.org/10.1038/s41467-021-22399-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055900PMC
April 2021

Impact of variant-level batch effects on identification of genetic risk factors in large sequencing studies.

PLoS One 2021 16;16(4):e0249305. Epub 2021 Apr 16.

Division of Computational Biology, Department of Quantitative Health Sciences, Mayo Clinic, Jacksonville, Florida, United States of America.

Genetic studies have shifted to sequencing-based rare variants discovery after decades of success in identifying common disease variants by Genome-Wide Association Studies using Single Nucleotide Polymorphism chips. Sequencing-based studies require large sample sizes for statistical power and therefore often inadvertently introduce batch effects because samples are typically collected, processed, and sequenced at multiple centers. Conventionally, batch effects are first detected and visualized using Principal Components Analysis and then controlled by including batch covariates in the disease association models. For sequencing-based genetic studies, because all variants included in the association analyses have passed sequencing-related quality control measures, this conventional approach treats every variant as equal and ignores the substantial differences still remaining in variant qualities and characteristics such as genotype quality scores, alternative allele fractions (fraction of reads supporting alternative allele at a variant position) and sequencing depths. In the Alzheimer's Disease Sequencing Project (ADSP) exome dataset of 9,904 cases and controls, we discovered hidden variant-level differences between sample batches of three sequencing centers and two exome capture kits. Although sequencing centers were included as a covariate in our association models, we observed differences at the variant level in genotype quality and alternative allele fraction between samples processed by different exome capture kits that significantly impacted both the confidence of variant detection and the identification of disease-associated variants. Furthermore, we found that a subset of top disease-risk variants came exclusively from samples processed by one exome capture kit that was more effective at capturing the alternative alleles compared to the other kit. Our findings highlight the importance of additional variant-level quality control for large sequencing-based genetic studies. More importantly, we demonstrate that automatically filtering out variants with batch differences may lead to false negatives if the batch discordances come largely from quality differences and if the batch-specific variants have better quality.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0249305PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8051815PMC
April 2021

Frequency of mutations in PRKN, PINK1, and DJ1 in Patients With Early-Onset Parkinson Disease from neighboring countries in Central Europe.

Parkinsonism Relat Disord 2021 May 2;86:48-51. Epub 2021 Apr 2.

Department of Neurology, Mayo Clinic, Jacksonville, FL, USA. Electronic address:

Introduction: Approximately 10% of patients with Parkinson disease (PD) present with early-onset disease (EOPD), defined as diagnosis before 50 years of age. Genetic factors are known to contribute to EOPD, with most commonly observed mutations in PRKN, PINK1, and DJ1 genes. The aim of our study was to analyze the frequency of PRKN, PINK1, and DJ1 mutations in an EOPD series from 4 neighboring European countries: Czech Republic, Germany, Poland, and Ukraine.

Methods: Diagnosis of PD was made based on UK Brain Bank diagnostic criteria in departments experienced in movement disorders (1 from Czech Republic, 1 from Germany, 9 from Poland, and 3 from Ukraine). EOPD was defined as onset at or before 50 years of age. Of the 541 patients recruited to the study, 11 were Czech, 38 German, 476 Polish, and 16 Ukrainian. All cohorts were fully screened with Sanger sequencing for PRKN, PINK1, and DJ1 and multiplex ligation-dependent probe amplification for exon dosage.

Results: PRKN homozygous or double heterozygous mutations were identified in 17 patients: 1 Czech (9.1%), 1 German (2.6%), 14 Polish (2.9%), and 1 Ukrainian (6.3%). PINK1 homozygous mutations were only identified in 3 Polish patients (0.6%). There were no homozygous or compound heterozygous DJ1 mutations in analyzed subpopulations. One novel variant in PRKN was identified in the Ukrainian series.

Conclusion: In the analyzed cohorts, mutations in the genes PRKN, PINK1, and DJ1 are not frequently observed.
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http://dx.doi.org/10.1016/j.parkreldis.2021.03.026DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192481PMC
May 2021

Coping with brain amyloid: genetic heterogeneity and cognitive resilience to Alzheimer's pathophysiology.

Acta Neuropathol Commun 2021 03 23;9(1):48. Epub 2021 Mar 23.

Department of Radiology, Mayo Clinic-Minnesota, 200 First Street SW, Rochester, MN, 55905, USA.

Although abnormal accumulation of amyloid in the brain is an early biomarker of Alzheimer's disease (AD), wide variation in cognitive trajectories during life can be seen in the setting of brain amyloidosis, ranging from maintenance of normal function to progression to dementia. It is widely presumed that cognitive resilience (i.e., coping) to amyloidosis may be influenced by environmental, lifestyle, and inherited factors, but relatively little in specifics is known about this architecture. Here, we leveraged multimodal longitudinal data from a large, population-based sample of older adults to discover genetic factors associated with differential cognitive resilience to brain amyloidosis determined by positron emission tomography (PET). Among amyloid-PET positive older adults, the AD risk allele APOE ɛ4 was associated with worse longitudinal memory trajectories as expected, and was thus covaried in the main analyses. Through a genome-wide association study (GWAS), we uncovered a novel association with cognitive resilience on chromosome 8 at the MTMR7/CNOT7/ZDHHC2/VPS37A locus (p = 4.66 × 10, β = 0.23), and demonstrated replication in an independent cohort. Post-hoc analyses confirmed this association as specific to the setting of elevated amyloid burden and not explained by differences in tau deposition or cerebrovascular disease. Complementary gene-based analyses and publically available functional data suggested that the causative variant at this locus may tag CNOT7 (CCR4-NOT Transcription Complex Subunit 7), a gene linked to synaptic plasticity and hippocampal-dependent learning and memory. Pathways related to cell adhesion and immune system activation displayed enrichment of association in the GWAS. Our findings, resulting from a unique study design, support the hypothesis that genetic heterogeneity is one of the factors that explains differential cognitive resilience to brain amyloidosis. Further characterization of the underlying biological mechanisms influencing cognitive resilience may facilitate improved prognostic counseling, therapeutic application, and trial enrollment in AD.
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http://dx.doi.org/10.1186/s40478-021-01154-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986461PMC
March 2021

PARKIN, PINK1, and DJ1 analysis in early-onset Parkinson's disease in Ireland.

Ir J Med Sci 2021 Mar 22. Epub 2021 Mar 22.

The Dublin Neurological Institute at the Mater Misericordiae University Hospital, Dublin, Ireland.

Background: Variants in PARKIN, PINK1, and DJ1 are associated with early-onset Parkinson' disease (EOPD, age-at-onset < 45). We previously reported a single PINK1 and a single DJ1 heterozygous variant carrier.

Purpose: We aimed to expand upon our previous EOPD studies and investigate for any genotype-phenotype correlations in Irish PD.

Methods: Three hundred fourteen PD patients were recruited from Dublin Neurological Institute, Ireland. Genetic analysis was performed at the Mayo Clinic, Jacksonville, USA. We screened 81 patients with young-onset PD (age-at-onset < 50), of which 58 had EOPD.

Results: We identified 4 patients with homozygous/compound heterozygous variants and 3 heterozygote carriers (pathogenic PINK1/DJ1 variants were not found). Expansion of one of the pedigrees showed a novel variant in exon 9, in a symptomatic patient. We identified 6.89% PARKIN variant carriers associated with EOPD.

Conclusion: These findings suggest that PINK1 and DJ1 are rarely associated with Irish YOPD, while PARKIN variant frequency is similar to that reported worldwide.
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http://dx.doi.org/10.1007/s11845-021-02563-wDOI Listing
March 2021

Early-Onset Parkinsonism and Early-Onset Parkinson's Disease: A Population-Based Study (2010-2015).

J Parkinsons Dis 2021 Mar 10. Epub 2021 Mar 10.

Department of Neurology, Mayo Clinic, Rochester, MN, USA.

Background: Early-onset Parkinson's disease (EOPD), occurring between ages 40 and 55, carries social, societal, and personal consequences and may progress, with fewer comorbidities than typical, later-onset disease.

Objective: To examine the incidence and survival of EOPD and other Parkinsonism occurring before age 55 in the population-based cohort of residents in seven Minnesota counties.

Methods: A movement-disorder specialist reviewed all the medical records in a 2010-2015 Parkinsonism-incident cohort to confirm diagnosis and subtypes.

Results: We identified 27 patients diagnosed at <  50 years with incident Parkinsonism 2010-15:11 (41%) cases of EOPD, 13 (48%) drug-induced Parkinsonism, and 3 (11%) other Parkinsonism and 69 incident cases of Parkinsonism <  55 years of age. Overall incidence for Parkinsonism <  50 years was 1.98/100,000 person-years, and for EOPD was 0.81/100,000 person-years. In patients <  55 years, Parkinsonism incidence was 5.05/100,000 person-years: in EOPD, 2.05/100,000 person-years. Levodopa-induced dyskinesia was present in 45%of EOPD (both <  50 years and <  55 years). Onset of cardinal motor symptoms was proximate to the diagnosis of EOPD, except for impaired postural reflexes, which occurred later in the course of EOPD. Among the 69 Parkinsonism cases <  55 years, 9 (13%; all male) were deceased (only 1 case of EOPD). Men had a higher mortality risk compared to women (p = 0.049).

Conclusion: The incidence of EOPD <  50 years was 0.81/100,000 person-years (1.98 in Parkinsonism all type); prior to 55 years was 2.05/100,000 person-years (5.05 in Parkinsonism all type) with higher incidence in men than women. Men with Parkinsonism, all type, had higher mortality compared to women.
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http://dx.doi.org/10.3233/JPD-202464DOI Listing
March 2021

Latent trait modeling of tau neuropathology in progressive supranuclear palsy.

Acta Neuropathol 2021 05 26;141(5):667-680. Epub 2021 Feb 26.

Department of Neuroscience, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

Progressive supranuclear palsy (PSP) is the second most common neurodegenerative Parkinsonian disorder after Parkinson's disease, and is characterized as a primary tauopathy. Leveraging the considerable clinical and neuropathologic heterogeneity associated with PSP, we measured tau neuropathology as quantitative traits to perform a genome-wide association study (GWAS) within PSP to identify genes and biological pathways that underlie the PSP disease process. In 882 PSP cases, semi-quantitative scores for phosphorylated tau-immunoreactive coiled bodies (CBs), neurofibrillary tangles (NFTs), tufted astrocytes (TAs), and tau threads were documented from 18 brain regions, and converted to latent trait (LT) variables using the R ltm package. LT analysis utilizes a multivariate regression model that links categorical responses to unobserved covariates allowing for a reduction of dimensionality, generating a single, continuous variable to account for the multiple lesions and brain regions assessed. We first tested for association with PSP LTs and the top PSP GWAS susceptibility loci. Significant SNP/LT associations were identified at rs242557 (MAPT H1c sub-haplotype) with hindbrain CBs and rs1768208 (MOBP) with forebrain tau threads. Digital microscopy was employed to quantify phosphorylated tau burden in midbrain tectum and red nucleus in 795 PSP cases and tau burdens were used as quantitative phenotypes in GWAS. Top associations were identified at rs1768208 with midbrain tectum and red nucleus tau burden. Additionally, we performed a PSP LT GWAS on an initial cohort, a follow-up SNP panel (37 SNPs, P < 10) in an extended cohort, and a combined analysis. Top SNP/LT associations were identified at SNPs in or near SPTBN5/EHD4, SEC13/ATP2B2, EPHB1/PPP2R3A, TBC1D8, IFNGR1/OLIG3, ST6GAL1, HK1, CALB1, and SGCZ. Finally, testing for SNP/transcript associations using whole transcriptome and whole genome data identified significant expression quantitative trait loci at rs3088159/SPTBN5/EHD4 and rs154239/GHRL. Modeling tau neuropathology heterogeneity using LTs as quantitative phenotypes in a GWAS may provide substantial insight into biological pathways involved in PSP by affecting regional tau burden.
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http://dx.doi.org/10.1007/s00401-021-02289-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8043857PMC
May 2021

Investigating ELOVL7 coding variants in multiple system atrophy.

Neurosci Lett 2021 04 15;749:135723. Epub 2021 Feb 15.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Mayo Graduate School Neuroscience Track, Mayo Clinic, Jacksonville, FL, USA; Department of Clinical Genomics, Mayo Clinic, Jacksonville, FL, USA. Electronic address:

Multiple system atrophy (MSA) is a rare sporadic, progressive parkinsonism characterised by autonomic dysfunction. A recent genome-wide association study reported an association at the Elongation of Very Long Fatty Acids Protein 7 (ELOVL7) locus with MSA risk. In the current study four independent and unrelated cohorts were assessed, consisting of pathologically confirmed MSA cases, Parkinson's disease (PD) cases, and two unrelated, healthy control groups. All exons of ELOVL7 were sequenced in pathologically confirmed MSA cases; data for PPMI samples and Biobank controls was extracted from whole genome sequence. Coding variants in ELOVL7 were extremely rare, and we observed no significant association of ELOVL7 coding variants with risk of MSA.
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http://dx.doi.org/10.1016/j.neulet.2021.135723DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7983070PMC
April 2021

Genome sequencing analysis identifies new loci associated with Lewy body dementia and provides insights into its genetic architecture.

Nat Genet 2021 03 15;53(3):294-303. Epub 2021 Feb 15.

Reta Lila Weston Institute, UCL Queen Square Institute of Neurology, University College London, London, UK.

The genetic basis of Lewy body dementia (LBD) is not well understood. Here, we performed whole-genome sequencing in large cohorts of LBD cases and neurologically healthy controls to study the genetic architecture of this understudied form of dementia, and to generate a resource for the scientific community. Genome-wide association analysis identified five independent risk loci, whereas genome-wide gene-aggregation tests implicated mutations in the gene GBA. Genetic risk scores demonstrate that LBD shares risk profiles and pathways with Alzheimer's disease and Parkinson's disease, providing a deeper molecular understanding of the complex genetic architecture of this age-related neurodegenerative condition.
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http://dx.doi.org/10.1038/s41588-021-00785-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7946812PMC
March 2021

Association of Mitochondrial DNA Genomic Variation With Risk of Pick Disease.

Neurology 2021 03 10;96(13):e1755-e1760. Epub 2021 Feb 10.

From the Department of Neuroscience (R.R.V., M.C.B., A.I.S.-B., R.L.W., S.K., S.F.R., R.R., D.W.D., O.A.R.), Division of Biomedical Statistics and Informatics (M.G.H., P.W.J.), Department of Neurology (R.J.U., Z.K.W.), and Department of Clinical Genomics (O.A.R.), Mayo Clinic, Jacksonville, FL; Perelman School of Medicine (E.S., J.Q.T., V.M.V.D.) and Department of Neurology (M.G.), University of Pennsylvania, Philadelphia; and VIB-UAntwerp Center for Molecular Neurology (R.R.), University of Antwerp, Belgium.

Objective: To determine whether stable polymorphisms that define mitochondrial haplogroups in mitochondrial DNA (mtDNA) are associated with Pick disease risk, we genotyped 52 pathologically confirmed cases of Pick disease and 910 neurologically healthy controls and performed case-control association analysis.

Methods: Fifty-two pathologically confirmed cases of Pick disease from Mayo Clinic Florida (n = 38) and the University of Pennsylvania (n = 14) and 910 neurologically healthy controls collected from Mayo Clinic Florida were genotyped for unique mtDNA haplogroup-defining variants. Mitochondrial haplogroups were determined, and in a case-control analysis, associations of mtDNA haplogroups with risk of Pick disease were evaluated with logistic regression models that were adjusted for age and sex.

Results: No individual mtDNA haplogroups or superhaplogroups were significantly associated with risk of Pick disease after adjustment for multiple testing ( < 0.0021, considered significant). However, nominally significant ( < 0.05) associations toward an increased risk of Pick disease were observed for mtDNA haplogroup W (5.8% cases vs 1.6% controls, odds ratio [OR] 4.78, = 0.020) and subhaplogroup H4 (5.8% cases vs 1.2% controls, OR 4.82, = 0.021).

Conclusion: Our findings indicate that mtDNA variation is not a disease driver but may influence disease susceptibility. Ongoing genetic assessments in larger cohorts of Pick disease are currently underway.
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http://dx.doi.org/10.1212/WNL.0000000000011649DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8055308PMC
March 2021

Genetics of Parkinson's disease in the Polish population.

Neurol Neurochir Pol 2021 4;55(3):241-252. Epub 2021 Feb 4.

Department of Neurology, Mayo Clinic Florida, United States.

Introduction: Genetic forms of Parkinson's disease (PD) often cluster in different ethnic groups and may present with recognisable unique clinical manifestations. Our aim was to summarise the current state of knowledge regarding the genetic causes of PD and describe the first Polish patient with SNCA duplication.

Methodology: We searched the electronic database, PubMed, for studies between January 1995 and June 2020 that evaluated genetics in Polish patients with PD, using the search terms 'Parkinson's disease, 'Polish', 'genetics', 'mutations', and 'variants'.

Results: In total, 73 publications were included in the review; 11 genes responsible for monogenic forms and 19 risk factor genes have been analysed in the Polish population. Pathogenic variants were reported in four monogenic genes (LRRK2, PRKN, PINK1, and SNCA). Eight genes were associated with PD risk in the Polish population (GBA, TFAM, NFE2L2, MMP12, HLA-DRA, COMT, MAOB, and DBH). Multiplex ligation-dependent probe amplification and Sanger sequencing in PRKN, PINK1, DJ1, LRRK2, and SNCA revealed SNCA duplication in a 43-year-old Polish patient with PD examined by movement disorder specialists.

Conclusion: Only a limited number of positive results have been reported in genes previously associated with PD in the Polish population. In the era of personalised medicine, it is important to report on genetic findings in specific populations.
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http://dx.doi.org/10.5603/PJNNS.a2021.0013DOI Listing
July 2021

Early-Onset Parkinson Disease Screening in Patients From Nigeria.

Front Neurol 2020 14;11:594927. Epub 2021 Jan 14.

Department of Neurology, Mayo Clinic Florida, Jacksonville, FL, United States.

Nigeria is one of the most populated countries in the world; however, there is a scarcity of studies in patients with age-related neurodegenerative diseases, such as Parkinson disease (PD). The aim of this study was to screen patients with PD including a small cohort of early-onset PD (EOPD) cases from Nigeria for multiplication, and LRRK2 p.G2019S. We assembled a cohort of 109 Nigerian patients with PD from the four main Nigerian tribes: Yoruba, Igbo, Edo, and Hausa. Fifteen cases [14 from the Yoruba tribe (93.3%)] had EOPD (defined as age-at-onset <50 years). All patients with EOPD were sequenced for the coding regions of , and . Exon dosage analysis was performed with a multiplex ligation-dependent probe amplification assay, which also included a probe and LRRK2 p.G2019S. We screened for LRRK2 p.G2019S in the entire PD cohort using a genotyping assay. The PINK1 p.R501Q functional analysis was conducted. In 15 patients with EOPD, 22 variants were observed [, 9 (40.9%); , 10 (45.5%); and , 3 (13.6%)]. Three (13.6%) rare, nonsynonymous variants were identified, but no homozygous or compound heterozygous carriers were found. No exonic rearrangements were present in the three genes, and no carriers of genomic multiplications or LRRK2 p.G2019S were identified. The PINK1 p.R501Q functional analysis revealed pathogenic loss of function. More studies on age-related neurodegenerative diseases are needed in sub-Saharan African countries, including Nigeria. Population-specific variation may provide insight into the genes involved in PD in the local population but may also contribute to larger studiesperformed in White and Asian populations.
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http://dx.doi.org/10.3389/fneur.2020.594927DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7841006PMC
January 2021

Frequency of spinocerebellar ataxia mutations in patients with multiple system atrophy.

Clin Auton Res 2021 Feb 27;31(1):117-125. Epub 2021 Jan 27.

Department of Neuroscience, Mayo Clinic Jacksonville, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

Purpose: Investigate single nucleotide variants and short tandem repeats in 39 genes related to spinocerebellar ataxia in clinical and pathologically defined cohorts of multiple system atrophy.

Methods: Exome sequencing was conducted in 28 clinical multiple system atrophy patients to identify single nucleotide variants in spinocerebellar ataxia-related genes. Novel variants were validated in two independent disease cohorts: 86 clinically diagnosed multiple system atrophy patients and 166 pathological multiple system atrophy cases. Expanded repeat alleles in spinocerebellar ataxia genes were evaluated in 36 clinically diagnosed multiple system atrophy patients, and CAG/CAA repeats in TATA-Box Binding Protein (TBP, causative of SCA17) were screened in 216 clinical and pathological multiple system atrophy patients and 346 controls.

Results: No known pathogenic spinocerebellar ataxia single nucleotide variants or pathogenic range expanded repeat alleles of ATXN1, ATXN2, ATXN3, CACNA1A, AXTN7, ATXN8OS, ATXN10, PPP2R2B, and TBP were detected in any clinical multiple system atrophy patients. However, four novel variants were identified in four spinocerebellar ataxia-related genes across three multiple system atrophy patients. Additionally, four multiple system atrophy patients (1.6%) and one control (0.3%) carried an intermediate length 41 TBP CAG/CAA repeat allele (OR = 4.11, P = 0.21). There was a significant association between the occurrence of a repeat length of longer alleles (> 38 repeats) and an increased risk of multiple system atrophy (OR = 1.64, P = 0.03).

Conclusion: Occurrence of TBP CAG/CAA repeat length of longer alleles (> 38 repeats) is significantly associated with increased multiple system atrophy risk. This discovery warrants further investigation and supports a possible genetic overlap of multiple system atrophy with SCA17.
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http://dx.doi.org/10.1007/s10286-020-00759-1DOI Listing
February 2021

Role of gut microbiota in regulating gastrointestinal dysfunction and motor symptoms in a mouse model of Parkinson's disease.

Gut Microbes 2021 Jan;13(1):1866974

Division of Gastroenterology and Hepatology, Mayo Clinic , Rochester, MN, USA.

Parkinson's disease (PD) is a common neurodegenerative disorder characterized primarily by motor and non-motor gastrointestinal (GI) deficits. GI symptoms' including compromised intestinal barrier function often accompanies altered gut microbiota composition and motor deficits in PD. Therefore, in this study, we set to investigate the role of gut microbiota and epithelial barrier dysfunction on motor symptom generation using a rotenone-induced mouse model of PD. We found that while six weeks of 10 mg/kg of chronic rotenone administration by oral gavage resulted in loss of tyrosine hydroxylase (TH) neurons in both germ-free (GF) and conventionally raised (CR) mice, the decrease in motor strength and coordination was observed only in CR mice. Chronic rotenone treatment did not disrupt intestinal permeability in GF mice but resulted in a significant change in gut microbiota composition and an increase in intestinal permeability in CR mice. These results highlight the potential role of gut microbiota in regulating barrier dysfunction and motor deficits in PD.
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http://dx.doi.org/10.1080/19490976.2020.1866974DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7833732PMC
January 2021

Fine-mapping of the non-coding variation driving the Caucasian LRRK2 GWAS signal in Parkinson's disease.

Parkinsonism Relat Disord 2021 02 11;83:22-30. Epub 2021 Jan 11.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; Department of Clinical Genomics, Mayo Clinic, Jacksonville, FL, USA. Electronic address:

Introduction: Genome-wide association studies (GWAS) have confirmed the leucine-rich repeat kinase 2 (LRRK2) gene as a susceptibility locus for idiopathic Parkinson's disease (PD) in Caucasians. Though the rs1491942 and rs76904798 variants have shown the strongest associations, the causal variant(s) remains unresolved. Therefore, the aim of this study was to identify variants that may be driving the LRRK2 GWAS signal by sequencing the entire LRRK2 gene in Caucasian PD patients and controls.

Methods: A discovery series (287 PD patients, 294 controls) and replication series (362 PD patients, 168 controls) were included. The entire LRRK2 gene as well as 10 Kb upstream/downstream was sequenced. Candidate potential causal variants were considered to be those that (a) were in at least weak linkage disequilibrium with the two GWAS-nominated variants (rs1491942 and rs76904798), and (b) displayed an association odds ratio (OR) that is stronger than the two GWAS variants.

Results: Thirty-four candidate variants (all intronic/intergenic) that may drive the LRRK2 PD GWAS signal were identified in the discovery series. However, examination of the replication series for these variants did not reveal any with a consistently stronger OR than both PD GWAS variants. Evaluation of public databases to determine which candidate variants are most likely to have a direct functional effect on LRRK2 expression was inconclusive.

Conclusion: Though our findings provide novel insights into the LRRK2 GWAS association, a clear causal variant was not identified. The identified candidate variants can form the basis for future experiments and functional studies that can more definitively assess causal LRRK2 variants.
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http://dx.doi.org/10.1016/j.parkreldis.2020.12.016DOI Listing
February 2021

Variants in and are associated with higher tau deposition.

Brain Commun 2020 26;2(2):fcaa159. Epub 2020 Sep 26.

Department of Radiology, Mayo Clinic-Minnesota, Rochester, MN 55905, USA.

Tau deposition is a key biological feature of Alzheimer's disease that is closely related to cognitive impairment. However, it remains poorly understood why certain individuals may be more susceptible to tau deposition while others are more resistant. The recent availability of assessment of tau burden through positron emission tomography provides an opportunity to test the hypothesis that common genetic variants may influence tau deposition. We performed a genome-wide association study of tau-positron emission tomography on a sample of 754 individuals over age 50 (mean age 72.4 years, 54.6% men, 87.6% cognitively unimpaired) from the population-based Mayo Clinic Study of Aging. Linear regression was performed to test nucleotide polymorphism associations with AV-1451 (F-flortaucipir) tau-positron emission tomography burden in an Alzheimer's-signature composite region of interest, using an additive genetic model and covarying for age, sex and genetic principal components. Genome-wide significant associations with higher tau were identified for rs76752255 (=9.91 × 10,  = 0.20) in the tau phosphorylation regulatory gene (protein phosphatase 2 regulatory subunit B) and for rs117402302 (=4.00 × 10,  = 0.19) near (insulin-like growth factor 2 mRNA-binding protein 3). The association remained genome-wide significant after additionally covarying for global amyloid burden and cerebrovascular disease risk, while the association was partially attenuated after accounting for amyloid load. In addition to these discoveries, three single nucleotide polymorphisms within (microtubule-associated protein tau) displayed nominal associations with tau-positron emission tomography burden, and the association of the (apolipoprotein E) ɛ4 allele with tau-positron emission tomography was marginally nonsignificant (=0.06,  = 0.07). No associations with tau-positron emission tomography burden were identified for other single nucleotide polymorphisms associated with Alzheimer's disease clinical diagnosis in prior large case-control studies. Our findings nominate and as novel potential influences on tau pathology which warrant further functional characterization. Our data are also supportive of previous literature on the associations of genetic variation with tau, and more broadly supports the inference that tau accumulation may have a genetic architecture distinct from known Alzheimer's susceptibility genes, which may have implications for improved risk stratification and therapeutic targeting.
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http://dx.doi.org/10.1093/braincomms/fcaa159DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7780444PMC
September 2020

Cilostazol Versus Aspirin for Secondary Stroke Prevention: Systematic Review and Meta-Analysis.

J Stroke Cerebrovasc Dis 2021 Mar 31;30(3):105581. Epub 2020 Dec 31.

Department of Neurology, Mayo Clinic, Jacksonville, FL, United States.

Objectives: Cilostazol has promise as an alternative to aspirin for secondary stroke prevention given its vasodilatory and anti-inflammatory properties in addition to platelet aggregation inhibition. We aimed to conduct a systematic review and meta-analysis to estimate the efficacy and safety of cilostazol compared to aspirin for stroke prevention in patients with previous stroke or transient ischemic attack (TIA).

Materials And Methods: We searched PubMed and the Cochrane Central Register of Controlled Trials from 1996 to 2019. Randomized clinical trials that compared cilostazol to aspirin and reported the endpoints of ischemic stroke, intracranial hemorrhage and any bleeding were included. A random-effects estimate was computed based on the Mantel-Haenszel method. The pooled risk estimates with 95% confidence intervals were compared between cilostazol and aspirin.

Results: The search identified 5 randomized clinical trials comparing cilostazol vs. aspirin for secondary stroke prevention that collectively enrolled 7240 patients, all from Asian countries (3615 received cilostazol and 3625 received aspirin). Pooled results from the random-effects model showed that cilostazol was associated with significantly lower risk of recurrent ischemic stroke (RR 0.68; 95% CI, 0.54 to 0.87), intracranial hemorrhage (RR 0.42; 95% CI, 0.27 to 0.65) and any bleeding (RR 0.71; 95% CI, 0.55 to 0.91).

Conclusions: This meta-analysis suggests that cilostazol is more effective than aspirin in preventing recurrent ischemic stroke with lower risk of intracranial hemorrhage and other bleeding. Since all trials to date are from Asian countries, confirmatory trials of cilostazol for secondary stroke prevention in other populations are needed.
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http://dx.doi.org/10.1016/j.jstrokecerebrovasdis.2020.105581DOI Listing
March 2021

Genetic determinants of survival in progressive supranuclear palsy: a genome-wide association study.

Lancet Neurol 2021 02 17;20(2):107-116. Epub 2020 Dec 17.

Department of Clinical and Movement Neurosciences, University College London Queen Square Institute of Neurology, London, UK; Movement Disorders Centre, University College London Queen Square Institute of Neurology, London, UK. Electronic address:

Background: The genetic basis of variation in the progression of primary tauopathies has not been determined. We aimed to identify genetic determinants of survival in progressive supranuclear palsy (PSP).

Methods: In stage one of this two stage genome-wide association study (GWAS), we included individuals with PSP, diagnosed according to pathological and clinical criteria, from two separate cohorts: the 2011 PSP GWAS cohort, from brain banks based at the Mayo Clinic (Jacksonville, FL, USA) and in Munich (Germany), and the University College London PSP cohort, from brain banks and the PROSPECT study, a UK-wide longitudinal study of patients with atypical parkinsonian syndromes. Individuals were included if they had clinical data available on sex, age at motor symptom onset, disease duration (from motor symptom onset to death or to the date of censoring, Dec 1, 2019, if individuals were alive), and PSP phenotype (with reference to the 2017 Movement Disorder Society criteria). Genotype data were used to do a survival GWAS using a Cox proportional hazards model. In stage two, data from additional individuals from the Mayo Clinic brain bank, which were obtained after the 2011 PSP GWAS, were used for a pooled analysis. We assessed the expression quantitative trait loci (eQTL) profile of variants that passed genome-wide significance in our GWAS using the Functional Mapping and Annotation of GWAS platform, and did colocalisation analyses using the eQTLGen and PsychENCODE datasets.

Findings: Data were collected and analysed between Aug 1, 2016, and Feb 1, 2020. Data were available for 1001 individuals of white European ancestry with PSP in stage one. We found a genome-wide significant association with survival at chromosome 12 (lead single nucleotide polymorphism rs2242367, p=7·5 × 10, hazard ratio 1·42 [95% CI 1·22-1·67]). rs2242367 was associated with survival in the individuals added in stage two (n=238; p=0·049, 1·22 [1·00-1·48]) and in the pooled analysis of both stages (n=1239; p=1·3 × 10, 1·37 [1·25-1·51]). An eQTL database screen revealed that rs2242367 is associated with increased expression of LRRK2 and two long intergenic non-coding RNAs (lncRNAs), LINC02555 and AC079630.4, in whole blood. Although we did not detect a colocalisation signal for LRRK2, analysis of the PSP survival signal and eQTLs for LINC02555 in the eQTLGen blood dataset revealed a posterior probability of hypothesis 4 of 0·77, suggesting colocalisation due to a single shared causal variant.

Interpretation: Genetic variation at the LRRK2 locus was associated with survival in PSP. The mechanism of this association might be through a lncRNA-regulated effect on LRRK2 expression because LINC02555 has previously been shown to regulate LRRK2 expression. LRRK2 has been associated with sporadic and familial forms of Parkinson's disease, and our finding suggests a genetic overlap with PSP. Further functional studies will be important to assess the potential of LRRK2 modulation as a disease-modifying therapy for PSP and related tauopathies.

Funding: PSP Association, CBD Solutions, Medical Research Council (UK).
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http://dx.doi.org/10.1016/S1474-4422(20)30394-XDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7116626PMC
February 2021

MAPT subhaplotypes in corticobasal degeneration: assessing associations with disease risk, severity of tau pathology, and clinical features.

Acta Neuropathol Commun 2020 12 7;8(1):218. Epub 2020 Dec 7.

Division of Biomedical Statistics and Informatics, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.

The microtubule-associated protein tau (MAPT) H1 haplotype is the strongest genetic risk factor for corticobasal degeneration (CBD). However, the specific H1 subhaplotype association is not well defined, and it is not clear whether any MAPT haplotypes influence severity of tau pathology or clinical presentation in CBD. Therefore, in the current study we examined 230 neuropathologically confirmed CBD cases and 1312 controls in order to assess associations of MAPT haplotypes with risk of CBD, severity of tau pathology (measured as semi-quantitative scores for coiled bodies, neurofibrillary tangles, astrocytic plaques, and neuropil threads), age of CBD onset, and disease duration. After correcting for multiple testing (P < 0.0026 considered as significant), we confirmed the strong association between the MAPT H2 haplotype and decreased risk of CBD (Odds ratio = 0.26, P = 2 × 10), and also observed a novel association between the H1d subhaplotype and an increased CBD risk (Odds ratio = 1.76, P = 0.002). Additionally, although not statistically significant after correcting for multiple testing, the H1c haplotype was associated with a higher risk of CBD (Odds ratio = 1.49, P = 0.009). No MAPT haplotypes were significantly associated with any tau pathology measures, age of CBD onset, or disease duration. Though replication will be important and there is potential that population stratification could have influenced our findings, these results suggest that several MAPT H1 subhaplotypes are primarily responsible for the strong association between MAPT H1 and risk of CBD, but that H1 subhaplotypes are unlikely to play a major role in driving tau pathology or clinical features. Our findings also indicate that similarities in MAPT haplotype risk-factor profile exist between CBD and the related tauopathy progressive supranuclear palsy, with H2, H1d, and H1c displaying associations with both diseases.
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http://dx.doi.org/10.1186/s40478-020-01097-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7720600PMC
December 2020

Lewy Body Disease is a Contributor to Logopenic Progressive Aphasia Phenotype.

Ann Neurol 2021 03 17;89(3):520-533. Epub 2020 Dec 17.

Department of Neurology, Mayo Clinic, Rochester, MN.

Objective: The objective of this study was to describe clinical features, [ F]-fluorodeoxyglucose (FDG)-positron emission tomography (PET) metabolism and digital pathology in patients with logopenic progressive aphasia (LPA) and pathologic diagnosis of diffuse Lewy body disease (DLBD) and compare to patients with LPA with other pathologies, as well as patients with classical features of probable dementia with Lewy bodies (pDLB).

Methods: This is a clinicopathologic case-control study of 45 patients, including 20 prospectively recruited patients with LPA among whom 6 were diagnosed with LPA-DLBD. We analyzed clinical features and compared FDG-PET metabolism in LPA-DLBD to an independent group of patients with clinical pDLB and regional α-synuclein burden on digital pathology to a second independent group of autopsied patients with DLBD pathology and antemortem pDLB (DLB-DLBD).

Results: All patients with LPA-DLBD were men. Neurological, speech, and neuropsychological characteristics were similar across LPA-DLBD, LPA-Alzheimer's disease (LPA-AD), and LPA-frontotemporal lobar degeneration (LPA-FTLD). Genetic screening of AD, DLBD, and FTLD linked genes were negative with the exception of APOE ε4 allele present in 83% of LPA-DLBD patients. Seventy-five percent of the patients with LPA-DLBD showed a parietal-dominant pattern of hy pometabolism; LPA-FTLD - temporal-dominant pattern, whereas LPA-AD showed heterogeneous patterns of hypometabolism. LPA-DLBD had more asymmetrical hypometabolism affecting frontal lobes, with relatively spared occipital lobe in the nondominantly affected hemisphere, compared to pDLB. LPA-DLBD had minimal atrophy on gross brain examination, higher cortical Lewy body counts, and higher α-synuclein burden in the middle frontal and inferior parietal cortices compared to DLB-DLBD.

Interpretation: Whereas AD is the most frequent underlying pathology of LPA, DLBD can also be present and may contribute to the LPA phenotype possibly due to α-synuclein-associated functional impairment of the dominant parietal lobe. ANN NEUROL 2021;89:520-533.
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http://dx.doi.org/10.1002/ana.25979DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8040336PMC
March 2021

Pathogenic Huntingtin Repeat Expansions in Patients with Frontotemporal Dementia and Amyotrophic Lateral Sclerosis.

Neuron 2021 02 26;109(3):448-460.e4. Epub 2020 Nov 26.

Molecular Markers Laboratory, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia 25125, Italy; MAC Memory Clinic, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia 25125, Italy.

We examined the role of repeat expansions in the pathogenesis of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) by analyzing whole-genome sequence data from 2,442 FTD/ALS patients, 2,599 Lewy body dementia (LBD) patients, and 3,158 neurologically healthy subjects. Pathogenic expansions (range, 40-64 CAG repeats) in the huntingtin (HTT) gene were found in three (0.12%) patients diagnosed with pure FTD/ALS syndromes but were not present in the LBD or healthy cohorts. We replicated our findings in an independent collection of 3,674 FTD/ALS patients. Postmortem evaluations of two patients revealed the classical TDP-43 pathology of FTD/ALS, as well as huntingtin-positive, ubiquitin-positive aggregates in the frontal cortex. The neostriatal atrophy that pathologically defines Huntington's disease was absent in both cases. Our findings reveal an etiological relationship between HTT repeat expansions and FTD/ALS syndromes and indicate that genetic screening of FTD/ALS patients for HTT repeat expansions should be considered.
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http://dx.doi.org/10.1016/j.neuron.2020.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7864894PMC
February 2021

Association of mitochondrial genomic background with risk of Multiple System Atrophy.

Parkinsonism Relat Disord 2020 12 29;81:200-204. Epub 2020 Oct 29.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA; Department of Clinical Genomics, Mayo Clinic, Jacksonville, FL 32224, USA; Department of Biology, University of North Florida, Jacksonville, FL 32224, USA. Electronic address:

Introduction: Multiple system atrophy (MSA) is a rare, sporadic, and progressive neurodegenerative disease which is characterized neuropathologically by alpha-synuclein aggregates in oligodendroglia, and clinically by parkinsonism, ataxia, and autonomic dysfunction. Mitochondrial health influences neurodegeneration and defects in mitochondria, particularly in oxidative phosphorylation, are reported in MSA. Mitochondrial DNA (mtDNA) codes for 13 critical OXPHOS proteins, however no study has investigated if mtDNA variation, in the form of mitochondrial haplogroups, influences MSA risk. Therefore, in this study we investigated the association of mtDNA haplogroups with MSA risk in a case-control manner.

Methods: 176 pathologically confirmed MSA cases and 910 neurologically healthy controls from Mayo Clinic Jacksonville were genotyped for 39 unique mtDNA variants using Agena Biosciences MassARRAY iPlex technology. Mitochondrial haplogroups were assigned to mitochondrial phylogeny, and logistic regression models that were adjusted for age and sex were used to assess associations between mitochondrial haplogroups and risk of MSA.

Results: After adjusting for multiple testing (P<0.0019 considered significant), no mitochondrial haplogroups were significantly associated with MSA risk. However, several nominally significant (P<0.05) associations were observed; haplogroup I was associated with a decreased risk of MSA (OR=0.09, P=0.021), while an increased risk of MSA was observed for haplogroups H3 (OR=2.43, P=0.017) and T1 and T2 (OR=2.04, P=0.007).

Conclusion: This study investigated whether population-specific mtDNA variation is associated with risk of MSA, and our nominally significant findings suggest mitochondrial haplogroup background may influence MSA risk. Validation of these findings and additional meta-analytic studies will be important.
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http://dx.doi.org/10.1016/j.parkreldis.2020.10.040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7769955PMC
December 2020

Plasma neurofilament light predicts mortality in patients with stroke.

Sci Transl Med 2020 11;12(569)

Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA.

Given the heterogeneity of stroke brain injury, there is a clear need for a biomarker that determines the degree of neuroaxonal injury across stroke types. We evaluated whether blood neurofilament light (NFL) would fulfill this purpose for patients with acute cerebral infarction (ACI; = 227), aneurysmal subarachnoid hemorrhage (aSAH; = 58), or nontraumatic intracerebral hemorrhage (ICH; = 29). We additionally validated our findings in two independent cohorts of patients with ICH ( = 96 and = 54) given the scarcity of blood biomarker studies for this deadliest stroke type. Compared to healthy individuals ( = 79 and = 48 for the discovery and validation cohorts, respectively), NFL was higher for all stroke types. NFL associated with radiographic markers of brain tissue damage. It correlated with the extent of early ischemic injury in patients with ACI, hemorrhage severity in patients with aSAH, and intracranial hemorrhage volume in patients with ICH. In all patients, NFL independently correlated with scores from the NIH Stroke Scale, the modified Rankin Scale, and the Mini-Mental State Examination at blood draw, which respectively assess neurological, functional, and cognitive status. Furthermore, higher NFL concentrations independently associated with 3- or 6-month functional disability and higher all-cause mortality. These data support NFL as a uniform method to estimate neuroaxonal injury and forecast mortality regardless of stroke mechanism. As a prognostic biomarker, blood NFL has the potential to assist with planning supportive and rehabilitation services and improving clinical trial efficiency for stroke therapeutics and devices.
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http://dx.doi.org/10.1126/scitranslmed.aay1913DOI Listing
November 2020

Sensitive ELISA-based detection method for the mitophagy marker p-S65-Ub in human cells, autopsy brain, and blood samples.

Autophagy 2020 Oct 28:1-16. Epub 2020 Oct 28.

Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.

Mitochondrial dysfunction is an early, imminent event in neurodegenerative disorders including Parkinson disease (PD) and Alzheimer disease (AD). The enzymatic pair PINK1 and PRKN/Parkin recognize and transiently label damaged mitochondria with ubiquitin (Ub) phosphorylated at Ser65 (p-S65-Ub) as a signal for degradation via the autophagy-lysosome system (mitophagy). Despite its discovery in cell culture several years ago, robust and quantitative detection of altered mitophagy has remained challenging. Here we developed a sandwich ELISA targeting p-S65-Ub with the goal to assess mitophagy levels in mouse brain and in human clinical and pathological samples. We characterized five total Ub and four p-S65-Ub antibodies by several techniques and found significant differences in their ability to recognize phosphorylated Ub. The most sensitive antibody pair detected recombinant p-S65-Ub chains in the femtomolar to low picomolar range depending on the poly-Ub chain linkage. Importantly, this ELISA was able to assess very low baseline mitophagy levels in unstressed human cells and in brains from wild-type and knockout mice as well as elevated p-S65-Ub levels in autopsied frontal cortex from AD patients vs. control cases. Moreover, the assay allowed detection of p-S65-Ub in blood plasma and was able to discriminate between mutation carriers and controls. In summary, we developed a robust and sensitive tool to measure mitophagy levels in cells, tissue, and body fluids. Our data strongly support the idea that the stress-activated PINK1-PRKN mitophagy pathway is constitutively active in mice and humans under unstimulated, physiological and elevated in diseased, pathological conditions.: Ab: antibody; AD: Alzheimer disease; AP: alkaline phosphatase; CV: coefficient of variation; ECL: electrochemiluminescence; KO: knockout; LoB: Limit of Blank; LoD: Limit of Detection; LoQ: Limit of Quantification; MSD: meso scale discovery; PD: Parkinson disease; p-S65-PRKN: phosphorylated PRKN at serine 65; p-S65-Ub: phosphorylated ubiquitin at serine 65; Std.Dev.: standard deviation; Ub: ubiquitin; WT: wild type.
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http://dx.doi.org/10.1080/15548627.2020.1834712DOI Listing
October 2020

Association of ABI3 and PLCG2 missense variants with disease risk and neuropathology in Lewy body disease and progressive supranuclear palsy.

Acta Neuropathol Commun 2020 10 22;8(1):172. Epub 2020 Oct 22.

Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL, 32224, USA.

Missense variants ABI3_rs616338-T and PLCG2_rs72824905-G were previously associated with elevated or reduced risk of Alzheimer's disease (AD), respectively. Despite reports of associations with other neurodegenerative diseases, there are few studies of these variants in purely neuropathologically diagnosed cohorts. Further, the effect of these mutations on neurodegenerative disease pathologies is unknown. In this study, we tested the effects of ABI3_rs616338-T and PLCG2_rs72824905-G on disease risk in autopsy cohorts comprised of 973 patients diagnosed neuropathologically with Lewy body disease (LBD-NP) and 1040 with progressive supranuclear palsy (PSP), compared to 3351 controls. LBD-NP patients were further categorized as high, intermediate and low likelihood of clinical dementia with Lewy bodies (DLB-CL) based on DLB Consortium criteria. We also tested for association with both Braak neurofibrillary tau tangle (n = 2008, n = 1037, n = 971) and Thal phase amyloid plaque scores (n = 1786, n = 1018, n = 768). Additionally, 841 PSP patients had quantitative tau neuropathology measures that were assessed for genetic associations. There was no statistically significant association with disease risk for either LBD-NP or PSP in our study. LBD intermediate category disease risk was significantly associated with ABI3_rs616338-T (OR = 2.65, 95% CI 1.46-4.83, p = 0.001). PLCG2_rs72824905-G was associated with lower Braak stage (ß = - 0.822, 95% CI - 1.439 to - 0.204, p = 0.009). This effect was more pronounced in the PSP (ß = - 0.995, 95% CI - 1.773 to - 0.218, p = 0.012) than LBD-NP patients (ß = - 0.292, 95% CI - 1.283 to 0.698, p = 0.563). PLCG2_rs72824905-G also showed association with reduced quantitative tau pathology for each lesion type and overall tau burden in PSP (ß = - 0.638, 95% CI - 1.139 to - 0.136, p = 0.013). These findings support a role for PLCG2_rs72824905-G in suppressing tau neuropathology. ABI3_rs616338-T may influence disease risk specifically in the LBD-NP intermediate category comprised of patients with diffuse neocortical or limbic LB, concurrently with moderate or high AD neuropathology, respectively. Our study provides a potential mechanism of action for the missense PLCG2 variant and suggests a differential disease risk effect for ABI3 in a distinct LBD-NP neuropathologic category.
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http://dx.doi.org/10.1186/s40478-020-01050-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7579984PMC
October 2020
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