Publications by authors named "Rosa Rademakers"

332 Publications

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
June 2021

FDG-PET in presymptomatic C9orf72 mutation carriers.

Neuroimage Clin 2021 Apr 25;31:102687. Epub 2021 Apr 25.

Division of Neurology, Department of Medicine, University of British Columbia. Electronic address:

Objective: Our aim is to investigate patterns of brain glucose metabolism using fluorodeoxyglucose positron emission tomography (FDG-PET) in presymptomatic carriers of the C9orf72 repeat expansion to better understand the early preclinical stages of frontotemporal dementia (FTD).

Methods: Structural MRI and FDG-PET were performed on clinically asymptomatic members of families with FTD caused by the C9orf72 repeat expansion (15 presymptomatic mutation carriers, C9orf72+; 20 non-carriers, C9orf72-). Regional glucose metabolism in cerebral and cerebellar gray matter was compared between groups.

Results: The mean age of the C9orf72+ and C9orf72- groups were 45.3 ± 10.6 and 56.0 ± 11.0 years respectively, and the mean age of FTD onset in their families was 56 ± 7 years. Compared to non-carrier controls, the C9orf72+ group exhibited regional hypometabolism, primarily involving the cingulate gyrus, frontal and temporal neocortices (left > right) and bilateral thalami.

Conclusions: The C9orf72 repeat expansion is associated with changes in brain glucose metabolism that are demonstrable up to 10 years prior to symptom onset and before changes in gray matter volume become significant. These findings indicate that FDG-PET may be a particularly sensitive and useful method for investigating and monitoring the earliest stages of FTD in individuals with this underlying genetic basis.
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http://dx.doi.org/10.1016/j.nicl.2021.102687DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8170157PMC
April 2021

Old age genetically confirmed frontotemporal lobar degeneration with TDP-43 has limbic predominant TDP-43 deposition.

Neuropathol Appl Neurobiol 2021 May 9. Epub 2021 May 9.

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

Aims: To assess the burden of transactive response DNA-binding protein of 43 kDa (TDP-43) inclusions in a unique cohort of old-age patients with genetic frontotemporal lobar degeneration (gFTLD-TDP) and compare these patients with sporadic old-age individuals with TDP-43, either in the presence of Alzheimer's disease (AD-TDP) or in isolation (pure-TDP).

Methods: The brain bank at Mayo Clinic-Jacksonville was searched for cases ≥75 years old at death with TDP-43 extending into middle frontal cortex. Cases were split into the following groups: (1) gFTLD-TDP (n = 15) with progranulin (GRN)/C9ORF72 mutations; (2) AD-TDP (n = 10)-cases with median Braak neurofibrillary tangle (NFT) stage VI, Thal phase V; (3) pure-TDP (n = 10)-cases with median Braak NFT stage I, Thal phase I. Clinical data were abstracted; TDP-43 burden was calculated using digital pathology.

Results: Amnestic Alzheimer's dementia was the clinical diagnosis in ≥50% patients in each group. The distribution of TDP-43 burden in gFTLD-TDP and AD-TDP, but not pure-TDP, was limbic-predominant targeting CA1 and subiculum. Patients with gFTLD-TDP had higher burden in entorhinal cortex compared to AD-TDP. TDP-43 burden in middle frontal cortex did not differ between the three groups.

Conclusions: In old age it is challenging to clinically and pathologically differentiate gFTLD-TDP from AD-TDP and pure-TDP-43 based on burden. Like AD-TDP, old age gFTLD-TDP have a limbic predominant TDP-43 distribution. The finding that amnestic Alzheimer's dementia was the most common clinical diagnosis regardless of group suggests that TDP-43 directly and indirectly targets limbic regions.
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http://dx.doi.org/10.1111/nan.12727DOI Listing
May 2021

Long-read targeted sequencing uncovers clinicopathological associations for C9orf72-linked diseases.

Brain 2021 May;144(4):1082-1088

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

To examine the length of a hexanucleotide expansion in C9orf72, which represents the most frequent genetic cause of frontotemporal lobar degeneration and motor neuron disease, we employed a targeted amplification-free long-read sequencing technology: No-Amp sequencing. In our cross-sectional study, we assessed cerebellar tissue from 28 well-characterized C9orf72 expansion carriers. We obtained 3507 on-target circular consensus sequencing reads, of which 814 bridged the C9orf72 repeat expansion (23%). Importantly, we observed a significant correlation between expansion sizes obtained using No-Amp sequencing and Southern blotting (P = 5.0 × 10-4). Interestingly, we also detected a significant survival advantage for individuals with smaller expansions (P = 0.004). Additionally, we uncovered that smaller expansions were significantly associated with higher levels of C9orf72 transcripts containing intron 1b (P = 0.003), poly(GP) proteins (P = 1.3 × 10- 5), and poly(GA) proteins (P = 0.005). Thorough examination of the composition of the expansion revealed that its GC content was extremely high (median: 100%) and that it was mainly composed of GGGGCC repeats (median: 96%), suggesting that expanded C9orf72 repeats are quite pure. Taken together, our findings demonstrate that No-Amp sequencing is a powerful tool that enables the discovery of relevant clinicopathological associations, highlighting the important role played by the cerebellar size of the expanded repeat in C9orf72-linked diseases.
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http://dx.doi.org/10.1093/brain/awab006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8105038PMC
May 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

Plasma Neurofilament Light for Prediction of Disease Progression in Familial Frontotemporal Lobar Degeneration.

Neurology 2021 05 7;96(18):e2296-e2312. Epub 2021 Apr 7.

From the University of California, San Francisco (J.C.R., P.W., A.M.S., Y.C., A.W., S.-Y.M.G., P.A.L., H.W.H., J.C.F., J.B.T., A.M.K., L.L.M., J.K., J.H.K., B.L.M., H.J.S., A.L.B.); UK Dementia Research Centre (C.H., D.M.C., R.S.C., M.B., M.F., C.V.G., G.P., L.R., I.S., E.T., J.D.R.), UCL Institute of Neurology, Queen Square, London; Quanterix Corp (E.V., L.S., A.J., D.H.), Lexington; Novartis Institutes for Biomedical Research Inc (L.Y., A. Khinikar, R.S.), Cambridge, MA; Novartis Pharma AG (A. Kieloch, M.-A.V.), Basel, Switzerland; Bluefield Project to Cure Frontotemporal Dementia (L.L.M., R.P.), San Francisco, CA; Mayo Clinic (K.K., D.S.K., B.F.B.), Rochester, MN; Mayo Clinic (N.G.-R., L.P., R.R.), Jacksonville, FL; University of Pennsylvania (D.J.I., M.G.), Philadelphia; University of California, Los Angeles (E.M.R., G.C., M.F.M., Y.B.); Harvard University/Massachusetts General Hospital (B.D.C.), Boston, MA; Washington University (N.G.), St. Louis, MO; Columbia University (E.D.H.), New York, NY; University of British Columbia (I.R.M., G.-Y.R.H.), Vancouver, Canada; Case Western Reserve University (B.S.A.), Cleveland, OH; University of Washington (K.D.-R.), Seattle; Laboratory of Neuroimaging (A.W.T.), University of Southern California, Los Angeles; Northwestern University (S.W.), Chicago, IL; University of North Carolina (D.I.K.), Chapel Hill; Texas Health Presbyterian Hospital Dallas (D.K.); University of California, San Diego (I.L.); Johns Hopkins Hospital (C.U.O., A.P.), Baltimore, MD; University of Alabama at Birmingham (E.D.R.); University of Toronto (M.C.T., M.M.), Ontario, Canada; Indiana University School of Medicine (T.F.), Indianapolis; Biogen Inc (W.C., J.C., D.L.G.), Cambridge, MA; Erasmus Medical Centre (J.C.v.S.), Rotterdam, the Netherlands; University of Brescia (B.B.), Italy; University of Barcelona (R.S.-V.); Donostia University Hospital (F.M.), San Sebastian, Gipuzkoa, Spain; Clinique Interdisciplinaire de Mémoire (R.L.), Département des Sciences Neurologiques, CHU de Québec; Faculté de Médecine (R.L.), Université Laval, Quebec, Canada; Center for Alzheimer Research (C.G.), Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Bioclinicum, Karolinska Institutet; Unit for Hereditary Dementias (C.G.), Theme Aging, Karolinska University Hospital, Solna, Sweden; University of Tübingen (M.S.); Center for Neurodegenerative Diseases (DZNE) (M.S.), Tübingen, Germany; Fondazione IRCCS Ospedale Policlinico (D.G.); University of Milan (D.G.), Centro Dino Ferrari, Italy; Department of Clinical Neurosciences and Cambridge University Hospital (J.B.R.), University of Cambridge, UK; University of Western Ontario (E.F.), London, Canada; KU Leuven (R.V.), Belgium; Neurology Service (R.V.), University Hospitals Leuven, Belgium; University of Lisbon (A.d.M.), Portugal; Fondazione IRCCS Istituto Neurologico Carlo Besta (F.T.), Milan, Italy; University of Coimbra (I.S.), Portugal; McGill University (S.D.), Montreal, Québec, Canada; University of Oxford (C.R.B.); Wolfson Molecular Imaging Centre (A.G.), University of Manchester, UK; University of Duisburg-Essen (A.G.), Duisberg; Ludwig-Maximilians-Universität München (J.L., A.D.); German Center for Neurodegenerative Diseases (J.L.), Munich Cluster for Systems Neurology (SyNergy); University of Ulm (M.O.), Germany; and Department of Neuroscience, Psychology, Drug Research and Child Health (S.S.), University of Florence, and IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy.

Objective: We tested the hypothesis that plasma neurofilament light chain (NfL) identifies asymptomatic carriers of familial frontotemporal lobar degeneration (FTLD)-causing mutations at risk of disease progression.

Methods: Baseline plasma NfL concentrations were measured with single-molecule array in original (n = 277) and validation (n = 297) cohorts. , , and mutation carriers and noncarriers from the same families were classified by disease severity (asymptomatic, prodromal, and full phenotype) using the CDR Dementia Staging Instrument plus behavior and language domains from the National Alzheimer's Disease Coordinating Center FTLD module (CDR+NACC-FTLD). Linear mixed-effect models related NfL to clinical variables.

Results: In both cohorts, baseline NfL was higher in asymptomatic mutation carriers who showed phenoconversion or disease progression compared to nonprogressors (original: 11.4 ± 7 pg/mL vs 6.7 ± 5 pg/mL, = 0.002; validation: 14.1 ± 12 pg/mL vs 8.7 ± 6 pg/mL, = 0.035). Plasma NfL discriminated symptomatic from asymptomatic mutation carriers or those with prodromal disease (original cutoff: 13.6 pg/mL, 87.5% sensitivity, 82.7% specificity; validation cutoff: 19.8 pg/mL, 87.4% sensitivity, 84.3% specificity). Higher baseline NfL correlated with worse longitudinal CDR+NACC-FTLD sum of boxes scores, neuropsychological function, and atrophy, regardless of genotype or disease severity, including asymptomatic mutation carriers.

Conclusions: Plasma NfL identifies asymptomatic carriers of FTLD-causing mutations at short-term risk of disease progression and is a potential tool to select participants for prevention clinical trials.

Trial Registration Information: ClinicalTrials.gov Identifier: NCT02372773 and NCT02365922.

Classification Of Evidence: This study provides Class I evidence that in carriers of FTLD-causing mutations, elevation of plasma NfL predicts short-term risk of clinical progression.
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http://dx.doi.org/10.1212/WNL.0000000000011848DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8166434PMC
May 2021

Neurobehavioral Characteristics of FDG-PET Defined Right-Dominant Semantic Dementia: A Longitudinal Study.

Dement Geriatr Cogn Disord 2021 Mar 23:1-12. Epub 2021 Mar 23.

Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA,

Introduction: Semantic dementia (SD) is characterized by fluent speech, anomia, and loss of word and object knowledge with varying degrees of right and left anterior-medial temporal lobe hypometabolism on [18F] fluorodeoxyglucose (FDG)-PET. We assessed neurobehavioral features in SD patients across 3 FDG-PET-defined metabolic patterns and investigated progression over time.

Methods: Thirty-four patients with SD who completed FDG-PET were classified into a left- and right-dominant group based on the degree of hypometabolism in each temporal lobe. The left-dominant group was further subdivided depending on whether hypometabolism in the right temporal lobe was more or less than 2 standard deviations from controls (left+ group). Neurobehavioral characteristics determined using the Neuropsychiatric Inventory Questionnaire (NPI-Q) were compared across groups. Progression of NPI-Q scores and FDG-PET hypometabolism was assessed in 14 patients with longitudinal follow-up.

Results: The right-dominant group performed worse on the NPI-Q and had a greater frequency of abnormal behaviors and more severe disinhibition compared to the left-dominant group. Performance on the NPI-Q and severity of disinhibition correlated with right medial and lateral, but not left, temporal lobe hypometabolism. Severity of abnormal behaviors worsened over time in most left-dominant and left+ patients but appeared to improve in the 2 right-dominant patients with longitudinal follow-up. All groups showed progressive worsening of metabolism in both temporal lobes over time, with hypometabolism spreading from anteromedial to posterior temporal regions. However, the degree of temporal lobe asymmetry remained relatively constant over time.

Conclusion: In SD, neurobehavioral features, especially disinhibition, are associated with right medial and lateral temporal lobe hypometabolism and commonly develop over time even in patients that present with left-dominant patterns of hypometabolism.
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http://dx.doi.org/10.1159/000513979DOI Listing
March 2021

Loss of Tmem106b leads to cerebellum Purkinje cell death and motor deficits.

Brain Pathol 2021 May 11;31(3):e12945. Epub 2021 Mar 11.

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

TMEM106B has been recently implicated in multiple neurodegenerative diseases. Here, Rademakers et al. report a late-onset cerebellar Purkinje cell loss and progressive decline in motor function and gait deficits in a conventional Tmem106b-/- mouse model. By using high-power microscopy and bulk RNA sequencing, the authors further identify lysosomal and immune dysfunction as potential underlying mechanisms of the Purkinje cell loss.
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http://dx.doi.org/10.1111/bpa.12945DOI Listing
May 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

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

Lysosomal Dysfunction and Other Pathomechanisms in FTLD: Evidence from Progranulin Genetics and Biology.

Adv Exp Med Biol 2021 ;1281:219-242

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

It has been more than a decade since heterozygous loss-of-function mutations in the progranulin gene (GRN) were first identified as an important genetic cause of frontotemporal lobar degeneration (FTLD). Due to the highly diverse biological functions of the progranulin (PGRN) protein, encoded by GRN, multiple possible disease mechanisms have been proposed. Early work focused on the neurotrophic properties of PGRN and its role in the inflammatory response. However, since the discovery of homozygous GRN mutations in patients with a lysosomal storage disorder, investigation into the possible roles of PGRN and its proteolytic cleavage products granulins, in lysosomal function and dysfunction, has taken center stage. In this chapter, we summarize the GRN mutational spectrum and its associated phenotypes followed by an in-depth discussion on the possible disease mechanisms implicated in FTLD-GRN. We conclude with key outstanding questions which urgently require answers to ensure safe and successful therapy development for GRN mutation carriers.
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http://dx.doi.org/10.1007/978-3-030-51140-1_14DOI Listing
February 2021

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

Machine learning suggests polygenic risk for cognitive dysfunction in amyotrophic lateral sclerosis.

EMBO Mol Med 2021 Jan 3;13(1):e12595. Epub 2020 Dec 3.

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

Amyotrophic lateral sclerosis (ALS) is a multi-system disease characterized primarily by progressive muscle weakness. Cognitive dysfunction is commonly observed in patients; however, factors influencing risk for cognitive dysfunction remain elusive. Using sparse canonical correlation analysis (sCCA), an unsupervised machine-learning technique, we observed that single nucleotide polymorphisms collectively associate with baseline cognitive performance in a large ALS patient cohort (N = 327) from the multicenter Clinical Research in ALS and Related Disorders for Therapeutic Development (CReATe) Consortium. We demonstrate that a polygenic risk score derived using sCCA relates to longitudinal cognitive decline in the same cohort and also to in vivo cortical thinning in the orbital frontal cortex, anterior cingulate cortex, lateral temporal cortex, premotor cortex, and hippocampus (N = 90) as well as post-mortem motor cortical neuronal loss (N = 87) in independent ALS cohorts from the University of Pennsylvania Integrated Neurodegenerative Disease Biobank. Our findings suggest that common genetic polymorphisms may exert a polygenic contribution to the risk of cortical disease vulnerability and cognitive dysfunction in ALS.
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http://dx.doi.org/10.15252/emmm.202012595DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7799365PMC
January 2021

Brain volumetric deficits in MAPT mutation carriers: a multisite study.

Ann Clin Transl Neurol 2021 01 28;8(1):95-110. Epub 2020 Nov 28.

Mayo Clinic, Jacksonville, Florida, USA.

Objective: MAPT mutations typically cause behavioral variant frontotemporal dementia with or without parkinsonism. Previous studies have shown that symptomatic MAPT mutation carriers have frontotemporal atrophy, yet studies have shown mixed results as to whether presymptomatic carriers have low gray matter volumes. To elucidate whether presymptomatic carriers have lower structural brain volumes within regions atrophied during the symptomatic phase, we studied a large cohort of MAPT mutation carriers using a voxelwise approach.

Methods: We studied 22 symptomatic carriers (age 54.7 ± 9.1, 13 female) and 43 presymptomatic carriers (age 39.2 ± 10.4, 21 female). Symptomatic carriers' clinical syndromes included: behavioral variant frontotemporal dementia (18), an amnestic dementia syndrome (2), Parkinson's disease (1), and mild cognitive impairment (1). We performed voxel-based morphometry on T1 images and assessed brain volumetrics by clinical subgroup, age, and mutation subtype.

Results: Symptomatic carriers showed gray matter atrophy in bilateral frontotemporal cortex, insula, and striatum, and white matter atrophy in bilateral corpus callosum and uncinate fasciculus. Approximately 20% of presymptomatic carriers had low gray matter volumes in bilateral hippocampus, amygdala, and lateral temporal cortex. Within these regions, low gray matter volumes emerged in a subset of presymptomatic carriers as early as their thirties. Low white matter volumes arose infrequently among presymptomatic carriers.

Interpretation: A subset of presymptomatic MAPT mutation carriers showed low volumes in mesial temporal lobe, the region ubiquitously atrophied in all symptomatic carriers. With each decade of age, an increasing percentage of presymptomatic carriers showed low mesial temporal volume, suggestive of early neurodegeneration.
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http://dx.doi.org/10.1002/acn3.51249DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818091PMC
January 2021

Sensitivity-Specificity of Tau and Amyloid β Positron Emission Tomography in Frontotemporal Lobar Degeneration.

Ann Neurol 2020 11 12;88(5):1009-1022. Epub 2020 Sep 12.

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

Objective: To examine associations between tau and amyloid β (Aβ) molecular positron emission tomography (PET) and both Alzheimer-related pathology and 4-repeat tau pathology in autopsy-confirmed frontotemporal lobar degeneration (FTLD).

Methods: Twenty-four patients had [ F]-flortaucipir-PET and died with FTLD (progressive supranuclear palsy [PSP], n = 10; corticobasal degeneration [CBD], n = 10; FTLD-TDP, n = 3; and Pick disease, n = 1). All but 1 had Pittsburgh compound B (PiB)-PET. Braak staging, Aβ plaque and neurofibrillary tangle counts, and semiquantitative tau lesion scores were performed. Flortaucipir standard uptake value ratios (SUVRs) were calculated in a temporal meta region of interest (meta-ROI), entorhinal cortex and cortical/subcortical regions selected to match the tau lesion analysis. Global PiB SUVR was calculated. Autoradiography was performed in 1 PSP patient, with digital pathology used to quantify tau burden.

Results: Nine cases (37.5%) had Aβ plaques. Global PiB SUVR correlated with Aβ plaque count, with 100% specificity and 50% sensitivity for diffuse plaques. Twenty-one (87.5%) had Braak stages I to IV. Flortaucipir correlated with neurofibrillary tangle counts in entorhinal cortex, but entorhinal and meta-ROI SUVRs were not elevated in Braak IV or primary age-related tauopathy. Flortaucipir uptake patterns differed across FTLD pathologies and could separate PSP and CBD. Flortaucipir correlated with tau lesion score in red nucleus and midbrain tegmentum across patients, but not in cortical or basal ganglia regions. Autoradiography demonstrated minimal uptake of flortaucipir, although flortaucipir correlated with quantitative tau burden across regions.

Interpretation: Molecular PET shows expected correlations with Alzheimer-related pathology but lacks sensitivity to detect mild Alzheimer pathology in FTLD. Regional flortaucipir uptake was able to separate CBD and PSP. ANN NEUROL 2020;88:1009-1022.
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http://dx.doi.org/10.1002/ana.25893DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7861121PMC
November 2020

Underlying genetic variation in familial frontotemporal dementia: sequencing of 198 patients.

Neurobiol Aging 2021 01 30;97:148.e9-148.e16. Epub 2020 Jul 30.

Department of Neurology & Alzheimer Center, Erasmus Medical Center, Rotterdam, the Netherlands.

Frontotemporal dementia (FTD) presents with a wide variability in clinical syndromes, genetic etiologies, and underlying pathologies. Despite the discovery of pathogenic variants in several genes, many familial cases remain unsolved. In a large FTD cohort of 198 familial patients, we aimed to determine the types and frequencies of variants in genes related to FTD. Pathogenic or likely pathogenic variants were revealed in 74 (37%) patients, including 4 novel variants. The repeat expansion in C9orf72 was most common (21%), followed by variants in MAPT (6%), GRN (4.5%), and TARDBP (3.5%). Other pathogenic variants were found in VCP, TBK1, PSEN1, and a novel homozygous variant in OPTN. Furthermore, we identified 15 variants of uncertain significance, including a promising variant in TUBA4A and a frameshift in VCP, for which additional research is needed to confirm pathogenicity. The patients without identified genetic cause demonstrated a wide clinical and pathological variety. Our study contributes to the clinical characterization of the genetic subtypes and confirms the value of whole-exome sequencing in identifying novel genetic variants.
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http://dx.doi.org/10.1016/j.neurobiolaging.2020.07.014DOI Listing
January 2021

Truncated stathmin-2 is a marker of TDP-43 pathology in frontotemporal dementia.

J Clin Invest 2020 11;130(11):6080-6092

Center for Genomics of Neurodegenerative Disease, and.

No treatment for frontotemporal dementia (FTD), the second most common type of early-onset dementia, is available, but therapeutics are being investigated to target the 2 main proteins associated with FTD pathological subtypes: TDP-43 (FTLD-TDP) and tau (FTLD-tau). Testing potential therapies in clinical trials is hampered by our inability to distinguish between patients with FTLD-TDP and FTLD-tau. Therefore, we evaluated truncated stathmin-2 (STMN2) as a proxy of TDP-43 pathology, given the reports that TDP-43 dysfunction causes truncated STMN2 accumulation. Truncated STMN2 accumulated in human induced pluripotent stem cell-derived neurons depleted of TDP-43, but not in those with pathogenic TARDBP mutations in the absence of TDP-43 aggregation or loss of nuclear protein. In RNA-Seq analyses of human brain samples from the NYGC ALS cohort, truncated STMN2 RNA was confined to tissues and disease subtypes marked by TDP-43 inclusions. Last, we validated that truncated STMN2 RNA was elevated in the frontal cortex of a cohort of patients with FTLD-TDP but not in controls or patients with progressive supranuclear palsy, a type of FTLD-tau. Further, in patients with FTLD-TDP, we observed significant associations of truncated STMN2 RNA with phosphorylated TDP-43 levels and an earlier age of disease onset. Overall, our data uncovered truncated STMN2 as a marker for TDP-43 dysfunction in FTD.
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http://dx.doi.org/10.1172/JCI139741DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7598060PMC
November 2020

Loss of Tmem106b exacerbates FTLD pathologies and causes motor deficits in progranulin-deficient mice.

EMBO Rep 2020 10 5;21(10):e50197. Epub 2020 Aug 5.

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

Progranulin (PGRN) and transmembrane protein 106B (TMEM106B) are important lysosomal proteins implicated in frontotemporal lobar degeneration (FTLD) and other neurodegenerative disorders. Loss-of-function mutations in progranulin (GRN) are a common cause of FTLD, while TMEM106B variants have been shown to act as disease modifiers in FTLD. Overexpression of TMEM106B leads to lysosomal dysfunction, while loss of Tmem106b ameliorates lysosomal and FTLD-related pathologies in young Grn mice, suggesting that lowering TMEM106B might be an attractive strategy for therapeutic treatment of FTLD-GRN. Here, we generate and characterize older Tmem106b Grn double knockout mice, which unexpectedly show severe motor deficits and spinal cord motor neuron and myelin loss, leading to paralysis and premature death at 11-12 months. Compared to Grn , Tmem106b Grn mice have exacerbated FTLD-related pathologies, including microgliosis, astrogliosis, ubiquitin, and phospho-Tdp43 inclusions, as well as worsening of lysosomal and autophagic deficits. Our findings confirm a functional interaction between Tmem106b and Pgrn and underscore the need to rethink whether modulating TMEM106B levels is a viable therapeutic strategy.
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http://dx.doi.org/10.15252/embr.202050197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534638PMC
October 2020

Quality of life and caregiver burden in familial frontotemporal lobar degeneration: Analyses of symptomatic and asymptomatic individuals within the LEFFTDS cohort.

Alzheimers Dement 2020 08 13;16(8):1115-1124. Epub 2020 Jul 13.

University of Pennsylvania, Philadelphia, Pennsylvania, USA.

Objective: The Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects evaluates familial frontotemporal lobar degeneration (FTLD) kindreds with MAPT, GRN, or C9orf72 mutations. Objectives were to examine whether health-related quality of life (HRQoL) correlates with clinical symptoms and caregiver burden, and whether self-rated and informant-rated HRQoL would correlate with each other.

Methods: Individuals were classified using the Clinical Dementia Rating (CDR ) Scale plus National Alzheimer's Coordinating Center (NACC) FTLD. HRQoL was measured with DEMQOL and DEMQOL-proxy; caregiver burden with the Zarit Burden Interview (ZBI). For analysis, Pearson correlations and weighted kappa statistics were calculated.

Results: The cohort of 312 individuals included symptomatic and asymptomatic individuals. CDR plus NACC FTLD was negatively correlated with DEMQOL (r = -0.20, P = .001), as were ZBI and DEMQOL (r = -0.22, P = .0009). There was fair agreement between subject and informant DEMQOL (κ = 0.36, P <.0001).

Conclusion: Lower HRQoL was associated with higher cognitive/behavior impairment and higher caregiver burden. These findings demonstrate the negative impact of FTLD on individuals and caregivers.
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http://dx.doi.org/10.1002/alz.12095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7534513PMC
August 2020

GBA variation and susceptibility to multiple system atrophy.

Parkinsonism Relat Disord 2020 08 22;77:64-69. Epub 2020 Jun 22.

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

Introduction: Genetic variants in the glucocerebrosidase (GBA) gene have been previously associated with susceptibility to synucleinopathies. The risk is well-established in Lewy body disease but is not as confirmed for multiple system atrophy (MSA). We aim to evaluate associations between exonic variants in GBA and risk of neuropathologically-confirmed multiple system atrophy (MSA).

Methods: Sanger gene sequencing of GBA was performed on 167 pathologically confirmed MSA patients collected at Mayo Clinic Florida Brain Bank, and data were extracted from whole-genome sequencing of 834 clinical controls. Common GBA variants were assessed for association with MSA. Rare GBA variants (and also all GBA variants) were collapsed together and evaluated for association with MSA risk using a gene-burden test.

Results: A total of 17 exonic GBA variants were observed, including a novel p.Q112X variant that is likely pathogenic in a patient with mixed parkinsonism-cerebellar subtype MSA. The more common p.N409S and p.L483P variants that recessively cause Gaucher's disease (GD), and are associated with risk of Lewy body disease, were not observed. When collapsing across all GBA variants, the presence of any GBA variant was significantly more frequent in MSA patients than in controls (OR = 1.90, P = 0.031). However, this association was driven by p.T408M, which had a significantly higher frequency in MSA patients compared to controls (OR = 4.21, P = 0.002). There was no significant association with risk of MSA for the p.E365K variant (OR = 0.79, P = 0.72).

Conclusions: Other than the specific GBA p.T408M variant, coding GBA variants are not associated with risk of MSA.
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http://dx.doi.org/10.1016/j.parkreldis.2020.06.007DOI Listing
August 2020

Longitudinal clinical, neuropsychological, and neuroimaging characterization of a kindred with a 12-octapeptide repeat insertion in : the next generation.

Neurocase 2020 08 30;26(4):211-219. Epub 2020 Jun 30.

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

Background: Highly penetrant inherited mutations in the prion protein gene () offer a window to study the pathobiology of prion disorders.

Method: Clinical, neuropsychological, and neuroimaging characterization of a kindred.

Results: Three of four mutation carriers have progressed to a frontotemporal dementia phenotype. Declines in neuropsychological function coincided with changes in FDG-PET at the identified onset of cognitive impairment.

Conclusions And Relevance: Gene silencing treatments are on the horizon and when they become available, early detection will be crucial. Longitudinal studies involving familial mutation kindreds can offer important insights into the initial neuropsychological and neuroimaging changes necessary for early detection.
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http://dx.doi.org/10.1080/13554794.2020.1787458DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7426006PMC
August 2020

Correction to: Loss of homeostatic microglial phenotype in CSF1R-related Leukoencephalopathy.

Acta Neuropathol Commun 2020 06 24;8(1):90. Epub 2020 Jun 24.

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

An amendment to this paper has been published and can be accessed via the original article.
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http://dx.doi.org/10.1186/s40478-020-00970-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7315469PMC
June 2020

Loss of TMEM106B leads to myelination deficits: implications for frontotemporal dementia treatment strategies.

Brain 2020 06;143(6):1905-1919

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

Genetic variants that define two distinct haplotypes at the TMEM106B locus have been implicated in multiple neurodegenerative diseases and in healthy brain ageing. In frontotemporal dementia (FTD), the high expressing TMEM106B risk haplotype was shown to increase susceptibility for FTD with TDP-43 inclusions (FTD-TDP) and to modify disease penetrance in progranulin mutation carriers (FTD-GRN). To elucidate the biological function of TMEM106B and determine whether lowering TMEM106B may be a viable therapeutic strategy, we performed brain transcriptomic analyses in 8-month-old animals from our recently developed Tmem106b-/- mouse model. We included 10 Tmem106b+/+ (wild-type), 10 Tmem106b+/- and 10 Tmem106-/- mice. The most differentially expressed genes (153 downregulated and 60 upregulated) were identified between Tmem106b-/- and wild-type animals, with an enrichment for genes implicated in myelination-related cellular processes including axon ensheathment and oligodendrocyte differentiation. Co-expression analysis also revealed that the most downregulated group of correlated genes was enriched for myelination-related processes. We further detected a significant loss of OLIG2-positive cells in the corpus callosum of Tmem106b-/- mice, which was present already in young animals (21 days) and persisted until old age (23 months), without worsening. Quantitative polymerase chain reaction revealed a reduction of differentiated but not undifferentiated oligodendrocytes cellular markers. While no obvious changes in myelin were observed at the ultrastructure levels in unchallenged animals, treatment with cuprizone revealed that Tmem106b-/- mice are more susceptible to cuprizone-induced demyelination and have a reduced capacity to remyelinate, a finding which we were able to replicate in a newly generated Tmem106b CRISPR/cas9 knock-out mouse model. Finally, using a TMEM106B HeLa knock-out cell line and primary cultured oligodendrocytes, we determined that loss of TMEM106B leads to abnormalities in the distribution of lysosomes and PLP1. Together these findings reveal an important function for TMEM106B in myelination with possible consequences for therapeutic strategies aimed at lowering TMEM106B levels.
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http://dx.doi.org/10.1093/brain/awaa141DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7296855PMC
June 2020

Loss of homeostatic microglial phenotype in CSF1R-related Leukoencephalopathy.

Acta Neuropathol Commun 2020 05 19;8(1):72. Epub 2020 May 19.

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

Microglia are resident macrophages of the central nervous system, and their unique molecular signature is dependent upon CSF-1 signaling. Previous studies have demonstrated the importance of CSF-1R in survival and development of microglia in animal models, but the findings are of uncertain relevance to understanding the influence of CSF-1R on microglia in humans. Hereditary diffuse leukoencephalopathy with spheroids (HDLS) [also known as adult onset leukoencephalopathy with spheroids and pigmented glia (ALSP)] is a neurodegenerative disorder primarily affecting cerebral white matter, most often caused by mutations of CSF1R. Therefore, we hypothesized that the molecular profile of microglia may be affected in HDLS. Semi-quantitative immunohistochemistry and quantitative transcriptomic profiling revealed reduced expression of IBA-1 and P2RY12 in both white and gray matter microglia of HDLS. In contrast, there was increased expression of CD68 and CD163 in microglia in affected white matter. In addition, expression of selective and specific microglial markers, including P2RY12, CX3CR1 and CSF-1R, were reduced in affected white matter. These results suggest that microglia in white matter in HDLS lose their homeostatic phenotype. Supported by gene ontology analysis, it is likely that an inflammatory phenotype is a key pathogenic feature of microglia in vulnerable brain regions of HDLS. Our findings suggest a potential mechanism of disease pathogenesis by linking aberrant CSF-1 signaling to altered microglial phenotype. They also support the idea that HDLS may be a primary microgliopathy. We observed increased expression of CSF-2 in gray matter compared to affected white matter, which may contribute to selective vulnerability of white matter in HDLS. Our findings suggest that methods that restore the homeostatic phenotype of microglia might be considered treatment approaches in HDLS.
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http://dx.doi.org/10.1186/s40478-020-00947-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7236286PMC
May 2020

Validation of serum neurofilaments as prognostic and potential pharmacodynamic biomarkers for ALS.

Neurology 2020 07 8;95(1):e59-e69. Epub 2020 May 8.

From Miller School of Medicine (M.B., L.Z., L.W., V.G., J.W.), University of Miami, FL; Kansas University Medical Center (J.S., R.B.), Kansas City; University of Iowa (A.S.), Iowa City; University of California San Diego (J.R.); University of Texas Health Science Center San Antonio (C.J.); University of Virginia (T.M.B.), Charlottesville; UT Southwestern Medical Center (J.T.), Dallas, TX; Cleveland Clinic (E.P.P.), OH; Wake Forest School of Medicine (J.C.), Winston-Salem, NC; California Pacific Medical Center (J.K.), San Francisco; John P Hussman Institute for Human Genomics (J.L.M.), Miami; Mayo Clinic Jacksonville (R.R.), FL; Blizard Institute (A.M.), Queen Mary University of London, UK; and Johns Hopkins University (L.W.O.), Baltimore, MD.

Objective: To identify preferred neurofilament assays and clinically validate serum neurofilament light (NfL) and phosphorylated neurofilament heavy (pNfH) as prognostic and potential pharmacodynamic biomarkers relevant to amyotrophic lateral sclerosis (ALS) therapy development.

Methods: In this prospective, multicenter, longitudinal observational study of patients with ALS (n = 229), primary lateral sclerosis (n = 20), and progressive muscular atrophy (n = 11), biological specimens were collected, processed, and stored according to strict standard operating procedures (SOPs). Neurofilament assays were performed in a blinded manner by independent contract research organizations.

Results: For serum NfL and pNfH measured using the Simoa assay, there were no missing data (i.e., technical replicates below the lower limit of detection were not encountered). For the Iron Horse and Euroimmun pNfH assays, such missingness was encountered in ∼4% and ∼10% of serum samples, respectively. Mean coefficients of variation for NfL in serum and CSF were both ∼3%. Mean coefficients of variation for pNfH in serum and CSF were ∼4%-5% and ∼2%-3%, respectively, in all assays. Baseline serum NfL concentration, but not pNfH, predicted the future Revised ALS Functional Rating Scale (ALSFRS-R) slope and survival. Incorporation of baseline serum NfL into mixed effects models of ALSFRS-R slopes yields an estimated sample size saving of ∼8%. Depending on the method used to estimate effect size, use of serum NfL (and perhaps pNfH) as pharmacodynamic biomarkers, instead of the ALSFRS-R slope, yields significantly larger sample size savings.

Conclusions: Serum NfL may be considered a clinically validated prognostic biomarker for ALS. Serum NfL (and perhaps pNfH), quantified using the Simoa assay, has potential utility as a pharmacodynamic biomarker of treatment effect.
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http://dx.doi.org/10.1212/WNL.0000000000009559DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371380PMC
July 2020

Revised Self-Monitoring Scale: A potential endpoint for frontotemporal dementia clinical trials.

Neurology 2020 06 5;94(22):e2384-e2395. Epub 2020 May 5.

From the Department of Neurology (G.T., K.R., Y.C., A.S., J. Fong, H.H., J.K., J.K., B.M., A.B., H.R., K.R.), Memory and Aging Center, University of California, San Francisco; Case Western Reserve University (B.A.), Cleveland, OH; Mayo Clinic (D.B., J. Fields, L.F., N.G.-R., K.K., D. Knopman, J.S., B.B.), Rochester, MN; University of California (G.C., M.M., E.R.), Los Angeles; Department of Neurology (B.D.), Massachusetts General Hospital, Harvard Medical School, Boston; University of Washington (K.D.-R.), Seattle; Washington University (N.G.), St. Louis, MO; University of Pennsylvania (M.G., D.I., K.R.), Philadelphia; University of British Columbia (G.-Y.H., I.M.), Vancouver, Canada; Columbia University (E.H.), New York, NY; University of North Carolina (D. Kaufer), Chapel Hill; University of Texas Southwestern (D. Kerwin), Dallas; Department of Neuroscience (I.L.), Parkinson and Other Movement Disorder Center, University of California, San Diego; Mayo Clinic (R.R.), Jacksonville, FL; University of Alabama at Birmingham (E.R.); University of Toronto (C.T.), Ontario, Canada; and Mesulam Center for Cognitive Neurology and Alzheimer's Disease (S.W.), Northwestern University, Chicago, IL.

Objective: To investigate whether the Revised Self-Monitoring Scale (RSMS), an informant measure of socioemotional sensitivity, is a potential clinical endpoint for treatment trials for patients with behavioral variant frontotemporal dementia (bvFTD).

Methods: We investigated whether RSMS informant ratings reflected disease severity in 475 participants (71 bvFTD mutation+, 154 bvFTD mutation-, 12 behavioral mild cognitive impairment [MCI] mutation+, 98 asymptomatic mutation+, 140 asymptomatic mutation-). In a subset of 62 patients (20 bvFTD mutation+, 35 bvFTD mutation-, 7 MCI mutation+) who had at least 2 time points of T1-weighted images available on the same 3T scanner, we examined longitudinal changes in RSMS score over time and its correspondence to progressive gray matter atrophy.

Results: RSMS score showed a similar pattern in mutation carriers and noncarriers, with significant drops at each stage of progression from asymptomatic to very mild, mild, moderate, and severe disease = 140.10, < 0.001) and a significant slope of decline over time in patients with bvFTD ( = 0.004, 95% confidence interval [CI] -1.90 to -0.23). More rapid declines on the RSMS corresponded to faster gray matter atrophy predominantly in the salience network (SN), and RSMS score progression best predicted thalamic volume in very mild and mild disease stages of bvFTD. Higher RSMS score predicted more caregiver burden ( < 0.001, 95% CI -0.30 to -0.11).

Conclusions: The RSMS is sensitive to progression of both socioemotional symptoms and SN atrophy in patients with bvFTD and corresponds directly to caregiver burden. The RSMS may be useful in both neurologic practice and clinical trials aiming to treat behavioral symptoms of patients with bvFTD.
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http://dx.doi.org/10.1212/WNL.0000000000009451DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7357291PMC
June 2020

Elevated methylation levels, reduced expression levels, and frequent contractions in a clinical cohort of C9orf72 expansion carriers.

Mol Neurodegener 2020 01 30;15(1). Epub 2020 Jan 30.

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

Background: A repeat expansion in the C9orf72-SMCR8 complex subunit (C9orf72) is the most common genetic cause of two debilitating neurodegenerative diseases: amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Currently, much remains unknown about which variables may modify these diseases. We sought to investigate associations between C9orf72 promoter methylation, RNA expression levels, and repeat length, their potential effects on disease features, as well as changes over time and within families.

Methods: All samples were obtained through the ALS Center at Mayo Clinic Florida. Our primary cohort included 75 unrelated patients with an expanded C9orf72 repeat, 33 patients who did not possess this expansion, and 20 control subjects without neurodegenerative diseases. Additionally, 67 members from 17 independent C9orf72 families were selected of whom 33 harbored this expansion. Longitudinally collected samples were available for 35 C9orf72 expansion carriers. To increase our understanding of C9orf72-related diseases, we performed quantitative methylation-sensitive restriction enzyme-based assays, digital molecular barcoding, quantitative real-time PCR, and Southern blotting.

Results: In our primary cohort, higher methylation levels were observed in patients with a C9orf72 repeat expansion than in patients without this expansion (p = 1.7e-13) or in control subjects (p = 3.3e-07). Moreover, we discovered that an increase in methylation levels was associated with a decrease in total C9orf72 transcript levels (p = 5.5e-05). These findings aligned with our observation that C9orf72 expansion carriers had lower expression levels of total C9orf72 transcripts than patients lacking this expansion (p = 3.7e-07) or control subjects (p = 9.1e-05). We also detected an elevation of transcripts containing intron 1a (upstream of the repeat) in patients carrying a C9orf72 repeat expansion compared to (disease) controls (p ≤ 0.01), an indication of abortive transcripts and/or a switch in transcription start site usage. While methylation and expression levels were relatively stable over time, fluctuations were seen in repeat length. Interestingly, contractions occurred frequently in parent-offspring transmissions (> 50%), especially in paternal transmissions. Furthermore, smaller repeat lengths were detected in currently unaffected individuals than in affected individuals (p = 8.9e-04) and they were associated with an earlier age at collection (p = 0.008).

Conclusions: In blood from C9orf72 expansion carriers, we found elevated methylation levels, reduced expression levels, and unstable expansions that tend to contract in successive generations, arguing against anticipation.
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http://dx.doi.org/10.1186/s13024-020-0359-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993399PMC
January 2020

Trajectory of lobar atrophy in asymptomatic and symptomatic GRN mutation carriers: a longitudinal MRI study.

Neurobiol Aging 2020 04 12;88:42-50. Epub 2019 Dec 12.

Department of Radiology, Mayo Clinic, Rochester, MN, USA; Alzheimer's Disease Research Center, Mayo Clinic, Rochester, MN, USA. Electronic address:

Loss-of-function mutations in the progranulin gene (GRN) are one of the major causes of familial frontotemporal lobar degeneration. Our objective was to determine the rates and trajectories of lobar cortical atrophy from longitudinal structural magnetic resonance imaging in both asymptomatic and symptomatic GRN mutation carriers. Individuals in this study were from the ADRC and LEFFTDS studies at the Mayo Clinic. We identified 13 GRN mutation carriers (8 asymptomatic, 5 symptomatic) and noncarriers (n = 10) who had at least 2 serial T1-weighted structural magnetic resonance images and were followed annually with a median of 3 years (range 1.0-9.8 years). Longitudinal changes in lobar cortical volume were analyzed using the tensor-based morphometry with symmetric normalization (TBM-SyN) algorithm. Linear mixed-effect models were used to model cortical volume change over time among 3 groups. The annual rates of frontal (p < 0.05) and parietal (p < 0.01) lobe cortical atrophy were higher in asymptomatic GRN mutation carriers than noncarriers. The symptomatic GRN mutation carriers also had increased rates of atrophy in the frontal (p < 0.01) and parietal lobe (p < 0.01) cortices than noncarriers. In addition, greater rates of cortical atrophy were observed in the temporal lobe cortices of symptomatic GRN mutation carriers than noncarriers (p < 0.001). We found that a decline in frontal and parietal lobar cortical volume occurs in asymptomatic GRN mutation carriers and continues in the symptomatic GRN mutation carriers, whereas an increased rate of temporal lobe cortical atrophy is observed only in symptomatic GRN mutation carriers. This sequential pattern of cortical involvement in GRN mutation carriers has important implications for using imaging biomarkers of neurodegeneration as an outcome measure in potential treatment trials involving GRN mutation carriers.
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http://dx.doi.org/10.1016/j.neurobiolaging.2019.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767622PMC
April 2020

Assessment of executive function declines in presymptomatic and mildly symptomatic familial frontotemporal dementia: NIH-EXAMINER as a potential clinical trial endpoint.

Alzheimers Dement 2020 01;16(1):11-21

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

Introduction: Identifying clinical measures that track disease in the earliest stages of frontotemporal lobar degeneration (FTLD) is important for clinical trials. Familial FTLD provides a unique paradigm to study early FTLD. Executive dysfunction is a clinically relevant hallmark of FTLD and may be a marker of disease progression.

Methods: Ninety-three mutation carriers with no symptoms or minimal/questionable symptoms (MAPT, n = 31; GRN, n = 28; C9orf72, n = 34; Clinical Dementia Rating scale plus NACC FTLD Module < 1) and 78 noncarriers enrolled through Advancing Research and Treatment in Frontotemporal Lobar Degeneration/Longitudinal Evaluation of Familial Frontotemporal Dementia Subjects studies completed the Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research (NIH-EXAMINER) and the UDS neuropsychological battery. Linear mixed-effects models were used to identify group differences in cognition at baseline and longitudinally. We examined associations between cognition, clinical functioning, and magnetic resonance imaging volumes.

Results: NIH-EXAMINER scores detected baseline and differences in slopes between carriers and noncarriers, even in carriers with a baseline Clinical Dementia Rating scale plus NACC FTLD Module = 0. NIH-EXAMINER declines were associated with worsening clinical symptoms and brain volume loss.

Discussion: The NIH-EXAMINER is sensitive to cognitive changes in presymptomatic familial FTLD and is a promising surrogate endpoint.
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http://dx.doi.org/10.1016/j.jalz.2019.01.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842665PMC
January 2020