article open access novel tuba4a

ARTICLE OPEN ACCESS

Novel TUBA4A Variant Associated With FamilialFrontotemporal DementiaMerel O Mol MD Tsz H Wong MD PhD ShamiramMelhem MSc Sreya Basu PhD Riccardo Viscusi MSc

Niels Galjart PhD Annemieke JM Rozemuller MD PhD Claudia Fallini PhD John E Landers MD PhD

Laura Donker Kaat MD PhD Harro Seelaar MD PhD Jeroen GJ van Rooij PhD and

John C van Swieten MD PhD

Neurol Genet 20217e596 doi101212NXG0000000000000596

Correspondence

Dr Mol

momolerasmusmcnl

AbstractObjectiveDespite the strong genetic component of frontotemporal dementia (FTD) a substantialproportion of patients remain genetically unresolved We performed an in-depth study of afamily with an autosomal dominant form of FTD to investigate the underlying genetic cause

MethodsFollowing clinical and pathologic characterization of the family genetic studies includedhaplotype sharing analysis and exome sequencing Subsequently we performed immunohis-tochemistry immunoblotting and a microtubule repolymerization assay to investigate thepotential impact of the candidate variant in tubulin alpha 4a (TUBA4A)

ResultsThe clinical presentation in this family is heterogeneous including behavioral changes par-kinsonian features and uncharacterized dementia Neuropathologic examination of 2 patientsrevealed TAR DNA binding protein 43 (TDP-43) pathology with abundant dystrophic neu-rites and neuronal intranuclear inclusions consistent with frontotemporal lobardegenerationndashTDP type A We identified a likely pathogenic variant in TUBA4A segregatingwith disease TUBA4A encodes for α-tubulin which is a major component of the microtubulenetwork Variants in TUBA4A have been suggested as a rare genetic cause of amyotrophiclateral sclerosis (ALS) and have sporadically been reported in patients with FTD withoutsupporting genetic segregation A decreased trend of TUBA4A protein abundance was ob-served in patients compared with controls and a microtubule repolymerization assay dem-onstrated disrupted α-tubulin function As opposed to variants found in ALS TUBA4A variantsassociated with FTD appear more localized to the N-terminus indicating different pathogenicmechanisms

ConclusionsOur findings support the role of TUBA4A variants as rare genetic cause of familial FTD

These authors contributed equally to this work as condashfirst authors

From the Department of Neurology (MOM THW SM LDK HS JGJvR JCvS) and Department of Cell Biology (SB RV NG) Erasmus Medical Center RotterdamDepartment of Pathology (AJMR) Amsterdam University Medical Center Location VUmc Amsterdam Neuroscience the Netherlands Department of Cell and Molecular Biology(CF) University of Rhode Island Kingston Department of Neurology (JEL) University of Massachusetts Medical School Worcester and Department of Clinical Genetics (LDK)Erasmus Medical Center Rotterdam the Netherlands

Go to NeurologyorgNG for full disclosures Funding information is provided at the end of the article

The Article Processing Charge was funded by Alzheimer Nederland (AN)

This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives License 40 (CC BY-NC-ND) which permits downloadingand sharing the work provided it is properly cited The work cannot be changed in any way or used commercially without permission from the journal

Copyright copy 2021 The Author(s) Published by Wolters Kluwer Health Inc on behalf of the American Academy of Neurology 1

Frontotemporal dementia (FTD) is a common type of early-onset dementia characterized by behavioral changes andcognitive impairment1 Up to 15 of patients developcomorbid amyotrophic lateral sclerosis (ALS)2 Because ofoverlap in clinical genetic and pathologic features both dis-orders are now considered part of a disease continuum3

Around a third of patients with FTD have a strong familyhistory although heritability is highly variable across sub-types4 The behavioral variant (bvFTD) is the most com-monly inherited form (45) followed by FTD withconcomitant motor neuron disease (FTD-MND) In con-trast most patients with a language variant (primary pro-gressive aphasia) are sporadic The majority of familial FTD iscaused by pathogenic changes in MAPT GRN or C9orf72Each genetic subtype accounts for5ndash10 of all FTD butgeographical variability is evident such as high occurrence ofGRN variants in Southern Europe5 Genetic forms of ALSrepresent approximately 5ndash10 of the total number of pa-tients with ALS67 Worldwide the C9orf72 repeat expansionis the most frequent cause of familial FTD and by far the mostcommon cause of familial ALS (30)7 Less prevalentvariants causing FTD andor ALS have been identified in gt10other genes such as TARDBP TBK1 VCP and TUBA4A89

Despite these rapid advances in the genetic architecture ofFTD many studies describe a subset of familial patientswithout identified genetic defect10-14 This suggests the exis-tence of yet undiscovered genes playing a role in the patho-genesis of FTD

In this study we describe the clinical and neuropathologicpresentation of a family with autosomal dominant FTD andpreviously unknown genetic defect Genetic analyses revealeda novel TUBA4A variant segregating with disease Additionalfunctional experiments strengthen the likely pathogenic roleof TUBA4A variants in FTD

MethodsAscertainment of PatientsWe studied 8 patients with dementia (onset le70 years) in aDutch family across 2 generations Three patients (II8 III6and III8) were clinically diagnosed with bvFTD by the in-vestigators according to international consensus criteria(figure 1)15 One patient (III5) had unspecified dementiawith parkinsonism as clinically determined by the investiga-tors The remaining 4 patients were diagnosed with

unspecified dementia or Parkinson disease (PD) before thisstudy (II1 II2 II3 and III1) As these 4 patients weredeceased further clinical data were collected by interviewingrelatives and reviewing medical records from hospitals ornursing homes In addition a relative with clinical late-onsetAlzheimer disease (LOAD II9) and 2 unaffected relatives(III2 and III12) were included Blood-derived DNA wasobtained from all 3 patients clinically diagnosed with bvFTD1 patient with unspecified dementia (III5) the relative af-fected by LOAD and the 2 unaffected relatives For a secondpatient with unspecified dementia (III1) DNA was extractedfrom formalin-fixed paraffin-embedded lymph node tissue aspreviously described16 Brain autopsy was performed in 2patients with bvFTD (II8 and III6) and confirmed the di-agnosis frontotemporal lobar degeneration (FTLD) Neuro-pathology was not available from the other deceased patients

Histology and ImmunohistochemistryNeuropathology was available from 2 patients clinically di-agnosed with bvFTD (II8 and III6) Brain autopsy was per-formed by the Netherlands Brain Bank (NBB) within 8 hoursafter death Routine immunohistochemistry was also performedby the NBBWe performed additional staining onmultiple brainregions including all cortical areas hippocampus and caudateputamen The following antibodies were used p62 (Lck Ligand610833 1100 BD Transduction Laboratories Franklin LakesNJ) Phospho-Tau (Ser202 Thr205) Monoclonal AntibodyAT8 (MN1020 1400 Thermo Fisher Scientific WalthamMA) Purified anti-β-Amyloid (4G8 800701 11000 BioL-egend SanDiego CA) and pTDP-43 (CAC-TIP-PTD-M01 11000 Cosmo Bio Carlsbad CA) The pattern of TDP-43 pa-thology was classified into subtypes according to the morphol-ogy and distribution of neuronal inclusions as proposed byNeumann et al17

Genetic AnalysesWe performed Sanger sequencing and repeat-primed PCR in2 patients with bvFTD (II8 and III6) to exclude a patho-genic or likely pathogenic variant in MAPT and GRN(according to the American College of Medical Genetics andGenomics guidelines)18 or a hexanucleotide repeat expansionin C9orf72 (gt30 repeats regarded as pathogenic)19

All 3 patients with bvFTD and 1 patient with unspecifieddementia (III5) were genotyped using Infinium GlobalScreening Array-24 v30 (Illumina San Diego CA) accordingto the manufacturerrsquos protocols Genotypes were called usingGenomeStudio 20 and quality control was performed using

GlossaryALS = amyotrophic lateral sclerosis bvFTD = behavioral variant FTDCADD =Combined Annotation-Dependent DepletionFTD = frontotemporal dementia FTD-MND = FTD with concomitant motor neuron disease FTLD = frontotemporal lobardegeneration GAPDH = glyceraldehyde-3-phosphate dehydrogenase GnomAD = Genome Aggregation Database HA =hemagglutinin LOAD = late-onset Alzheimer diseaseNBB = Netherlands Brain BankNCI = neuronal cytoplasmic inclusionNII = neuronal intranuclear inclusion PD = Parkinson disease TDP-43 = TAR DNA binding protein 43 WT = wild type

2 Neurology Genetics | Volume 7 Number 3 | June 2021 NeurologyorgNG

PLINK20 We performed a haplotype sharing analysis byscanning all SNPs and computing the length of the sharedhaplotypes in megabase as described previously21

The same 3 patients with bvFTD 2 patients with unspecifieddementia (III5 and III1) and 1 unaffected relative (III2) wereselected for exome sequencing by Centogene AG (RostockGermany) using the Nextera Rapid Capture Exome Kit (Illu-mina) The included patients all had an early onset of disease andthe unaffected relative had passed this age Unfortunately DNAof patient III1 was scarce and therefore this patient could notbe included in both the array and the exome sequencing

Bioinformatic details can be found in the e-Methods (linkslwwcomNXGA426) Variants were annotated usingANNOVAR22 and only those variants with a quality scoregt200 and coverage gt50 in each sample were considered forsubsequent analysis Filtering was applied to include the fol-lowing variants (1) segregating heterozygous with disease inthe 5 affected patients and 1 unaffected relative (2) non-synonymous or protein truncating including frameshiftindels and (3) minor allele frequency of lt001 in GenomeAggregation Database (GnomAD) The remaining candidatevariants were evaluated regarding average brain expression(GTEx Project) and Combined Annotation-Dependent De-pletion (CADD) score23 and validated by Sanger sequencing(Applied Biosystems Foster City CA)

TUBA4A Immunohistochemistryand ImmunoblottingImmunohistochemistry was performed using anti-TUBA4A(228701 1500 Abcam Cambridge UK) on frontal and

temporal cortex tissue of patients II8 and III6 (aged 75 and70 years respectively) 3 nondemented controls (NDCs)(age range 88ndash92 years) 3 unrelated patients with FTLD-TDP type A due to pathogenic variant in GRN (age range58ndash76 years [pSer82ValfsX174 and pGln300X]) 3 un-related patients with FTLD-TDP type B due to a C9orf72repeat expansion (age range 67ndash80 years) and 3 unrelatedpatients with AD (age range 64ndash75 years) Protein wasextracted from postmortem frozen temporal cortex tissue ofthe same 2 patients 5 unrelated NDCs (mean age 78 range56ndash92 years) 2 unrelated patients with FTD with a patho-genic variant in GRN (aged 63 [pCys105fs] and 66[pGln300X] years) and 2 unrelated patients with AD (aged90 and 91 years) Immunoblotting was performed on thesecases in biological triplicates with separate protein isolationsfrom 30-μm tissue sections Each isolate was subsequentlyblotted in duplicates The following primary antibodies wereused rabbit anti-TUBA4A (18000 AP13535b Abcepta)and rabbit anti-glyceraldehyde-3-phosphate dehydrogenase(GAPDH) (11000 GTX100118 Genetex) GAPDH wasused as housekeeping gene to normalize between blots Fur-ther details can be found in the e-Methods (linkslwwcomNXGA426) Results were quantified and the relativeabundances of TUBA4A in patients were normalized to themean of NDCs

Microtubule Repolymerization AssayCOS1 and COS7 cells were cultured in Dulbeccorsquos ModifiedEagle Medium supplemented with 10 fetal bovine serumand 1 PenStrep and transfected using X-tremeGENE HD(Roche Basel Switzerland) according to the manufacturerrsquosinstructions with hemagglutinin (HA)-tagged wild-type

Figure 1 Pedigree of the Family

Filled black symbols represent affected patients Deceased patients are marked by a diagonal line Numbers within the symbols represent additionalunaffected relatives Numbers in parentheses indicate age at death or age at last evaluation Brain autopsy was performed in the 2 patients marked byasterisk Individual II9 was considered a patient with sporadic late-onset AD and was not included in the initial genetic analyses Four patients (blue marks)were included in the haplotype sharing analysis Exome sequencing was performed including these 4 patients and 2 relatives (red marks) Two additionalrelatives were tested for the TUBA4A R105C variant by Sanger sequencing Men andwomanwere affected equally (sexmasked for anonymity) TUBA4A R105Cstatus +minus = carrier minusminus = noncarrier upper row whole-exome sequencing (WES) lower row Sanger sequencing Patient III1 was not tested by Sanger due tolack of DNA AD = Alzheimer disease bvFTD = behavioral variant of frontotemporal dementia na = not available PD = Parkinson disease UD = unspecifieddementia

NeurologyorgNG Neurology Genetics | Volume 7 Number 3 | June 2021 3

(WT) tubulin R105C or R320C mutant constructs Theexpression levels of the constructs were assessed by immu-noblotting and we evaluated cell viability of WT comparedwith the R105C construct by fixing the cells after 24 48 and72 hours Twenty-four hours after transfection COS1 cellswere treated with 10 μM nocodazole (a potent microtubuledepolymerizing agent) for 2 hours at 37degC and allowed torecover in nocodazole-free medium for 0 5 10 and 30 mi-nutes before fixation with cold methanol at minus20degC for 10minutes The following primary antibodies were used rabbitanti-β-tubulin antibody (Abcam ab6046) and mouse anti-HAantibody (Cell Signaling Technologies Danvers MA 2367)To assess recovery after nocodazole washout we acquired8ndash10 images by confocal microscopy using identical settingsfor each condition and time point We counted the number oftransfected cells positive for (1) endogenous asters andormicrotubule staining as visualized with anti-β-tubulin anti-body and (2) HA-TUBA4A WT R105C and R320C in-corporation at asters and microtubules visualized with anti-HA antibody Results were combined from 2 independentexperiments

Microtubule Integrity AssayTo examine the integrity of the microtubules on expression ofthe various TUBA4A constructs we cotransfected COS7 cellswith HA-tagged tubulin and EMTB-mCherry an indirectfluorescent marker of microtubules24 After transfection cellswere fixed and mCherry signal was imaged and quantified toassess the overall integrity of the microtubule network asdescribed previously25 A more detailed description of theexperiments is provided in the e-Methods (linkslwwcomNXGA426)

Standard Protocol Approvals Registrationsand Patient ConsentsThe study was approved by theMedical Ethical Committee ofthe Erasmus Medical Center Rotterdam the NetherlandsEthical approval for the NBB procedures was given by theMedical Ethics Committee of the VU University MedicalCenter Amsterdam the Netherlands Informed consent forthe use of tissue clinical and neuropathologic data wasobtained from all participants or their legal representativesBrain autopsy was conducted by the NBB at the designatedpremises of VU Medical Center according to the Code ofconduct for Brain Banking and Declaration of Helsinki

Data AvailabilityAdditional immunohistochemistry images are available fromthe here studied material which we are willing to share

ResultsClinical FindingsMultiple relatives presented with different forms of dementiain our clinic with an apparent autosomal dominant in-heritance pattern The family structure is presented in figure 1and the main clinical features of all 8 patients are summarizedin table 1 The median age at onset was 655 years (range59ndash70 years) 7 patients died after a median disease durationof 8 years (range 6ndash11 years)

Three patients (II8 III6 and III8) were diagnosed withbvFTD Primary symptoms included disinhibition emotionalblunting self-neglect and lack of initiative Patients III6 and

Table 1 Summary of Demographics and Clinical Symptoms of the 8 Patients Included in the Study

PatientAge atonset y

Age atdeath y

Diseaseduration y

Clinicaldiagnosis

Clinicalsymptoms

Brain atrophyatneuroimaging

FDG-PET PathologyTUBA4A R105CstatusB L M P G FT H

II1 68 77 9 UD ++ plusmn NA NA NA NA

II2 66 72 8 PD minus plusmn ++ NA NA NA NA

II3 70 76 6 UD plusmn ++ NA NA NA NA

II8a 64 75 11 bvFTD ++ plusmn plusmn minus minus ++ minus NA FTLD-TDP Heterozygous

III1 68 77 9 UD ++ minus plusmn NA NA NA Heterozygous

III5a 65 71 6 UD plusmn minus ++ ++ plusmn plusmn + NA NA Heterozygous

III6a 64 70 6 bvFTD ++ + plusmn minus plusmn plusmn plusmn darr frontaluptake

FTLD-TDP Heterozygous

III8a 59 mdash 8 bvFTD ++ plusmn plusmn minus plusmn ++ + darr frontaluptake

NA Heterozygous

Abbreviations B = behavioral changes bvFTD = behavioral variant of FTD FT = frontotemporal FTLD-TDP = frontotemporal lobar degeneration with TDPpathology G = generalized H = hippocampus L = language impairment M = memory complaints NA = not available P = parkinsonism PD = Parkinsondisease UD = unspecified dementia minus = absence plusmn = mild + = moderate ++ = severe = unknowna Personally examined by the investigators Information from the others was obtained by interviewing relatives and reviewing medical records All patientshave died except for patient III8 for whom current disease duration is presented Brain autopsy was performed in 2 patients (II8 and III6)


III8 also experienced gait disturbances with stiffness and theoccasional fall though without evident parkinsonian symptomsor ataxia at neurologic examination No clinical signs of motorneuron disease were found Neuropsychological assessment inall 3 patients revealed a frontal syndrome with apathy deficits inabstract reasoning language impairment and executive dys-function with relative preservation of episodic memory Fron-totemporal atrophy was observed in patient II8 on CT scanFDG-PET in patients III6 and III8 revealed frontal hypo-metabolism consistent with the diagnosis of bvFTD

Another patient (III5) presented primarily withmemory deficitsfrom age 65 years without prominent behavioral symptoms andcomplaints of an unsteady gait Neurologic examination revealedhypomimia bradykinesia a shuffling gait and slight rigidity inthe upper limbs unresponsive to treatment with levodopa Re-peated neuropsychological evaluation exposed an apatheticpresentation with passivity and perseverance deficits in atten-tion visual perception and executive functioning but intactorientation which did not fit AD nor FTD Brain MRI showedmild generalized cortical atrophy and moderate hippocampalatrophy The patient deteriorated rapidly over the followingyears and died at age 71 years

Three patients (III1 II1 and II3) were diagnosed elsewherewith unspecified dementia with onset le70 years Medical recordsof patient III1 described prominent behavioral changes withexcessive spending wandering suspicion and self-neglect sug-gestive of bvFTD Relatives indicated that patient II1 (parent ofIII1) had shown similar symptoms One additional patient (II2)was reported to have PD from age 66 years with gait disturbancesdysarthria and mild cognitive impairment Two unaffected rela-tives (III2 and III12) were examined at ages 77 and 49 yearsrespectively and showed no cognitive or behavioral symptoms

Histology and ImmunohistochemistryPathology was available of patients III6 and II8 both clini-cally diagnosed with bvFTD and deceased at ages 70 and 75respectively Gross examination of patient III6 revealed asmall symmetrical brain (1160 g) with slight bilateral frontalatrophy and dilatation of the ventricles At microscopy thefrontal cortex showedmild gliosis and spongiosis especially ofthe third layer Moderate to severe neuronal loss was seen inthe hippocampus in the entorhinal cortex CA1 and sub-iculum Low numbers of AT8-positive neurofibrillary tanglesand neuropil threads were found in the transentorhinal regionand amyloid plaques in all isocortical areas (Braak stage I-IIamyloid B) FTLD-TDP pathology was confirmed by abun-dant p62 and phospho-TDP immunoreactive short dystro-phic neurites neuronal cytoplasmic inclusions (NCIs) andneuronal intranuclear inclusion (NII) of various morphol-ogies observed primarily in the superficial layers of the tem-poral cortex (figure 2 A and B) No white matter glialinclusions were found TDP pathology was also present in thefrontal cortex hippocampus and putamencaudate nucleuswhich displayed many NCI and sporadically a lentiform NIIThe parietal cortex contained a few NCI but lacked NIIAccording to Neumann et al17 these findings are mostlyconsistent with FTLD-TDP subtype A Neuropathology ofpatient II8 (brain weight 1216 g) revealed a similar distri-bution of TDP pathology most apparent in the temporalcortex and hippocampus (figure 2 C and D)

Genetic AnalysesHaplotype sharing analysis of 3 patients with clinical bvFTD(II8 III6 and III8) and 1 patient with unspecified dementia(III5) revealed multiple shared haplotype blocks (figure e-1linkslwwcomNXGA426) Filtering of exome sequencingdata of the same 4 patients another relative affected by

Figure 2 Immunohistochemistry of Patients III6 and II8 Confirming FTLD-TDP Pathology

The pathologic subtype of both patients resem-bles TDP type A considering the short and thickdystrophic neurites (DN) compact neuronal cy-toplasmic inclusions (NCIs) and lentiform neu-ronal intranuclear inclusions (NIIs) mostly in thesuperficial layers of the cortex The deeper layerswere also affected but to lesser extent (A) Im-ages of P62 staining (including 3 insets of a varietyof neuronal inclusions) and (B) pTDP staining inpatient III6 show the DN NCI and NII in thesecond layer of temporal cortex Staining withpTDP of patient II8 revealed similar findings withinclusions in (C) the dentate gyrus of hippocam-pus and (D) second layer of temporal cortex (in-cluding 3 insets of neuronal inclusions) Scale bar20 μm FTLD-TDP = frontotemporal lobar de-generation with TDP pathology


unspecified dementia (III1) and 1 unaffected relative (III2)revealed 4 candidate missense variants located in the genesTUBA4A ZNF142 PTPRE and ARAP3 (table e-1) which alloverlapped with the shared haplotype blocks Among these onlyTUBA4A has previously been associated with ALSFTD Theheterozygous TUBA4A variant NM_0060002c313CgtT(pR105C) is located in exon 3 in the intermediate protein do-main GTPase is absent in GnomAD and in silico predictionsindicate a pathogenic effect (CADD 32 SIFT 0 PolyPhen 09MutationTaster D) The genetic variants in the other 3 genesare not associated with neurodegenerative disease Althoughnonsense and frameshift variants in ZNF142 have been associ-ated with a complex neurodevelopmental disorder26 the averagebrain expression in adults is much lower compared withTUBA4A (table e-1) Altogether TUBA4A was the most likelycandidate and prioritized for additional analyses

All 4 variants were confirmed by Sanger sequencing in all 3 pa-tientswith bvFTDand 1patientwith unspecified dementia (III5)(table 1 and figure 1) Patient III1was not tested by Sanger due tolack of DNA Additional sequencing of the TUBA4A variantconfirmed absence in 2 unaffected relatives (III2 and III12) and arelative clinically diagnosed with LOAD (II9)

TUBA4A Immunohistochemistryand ImmunoblottingAdditional immunohistochemistry with TUBA4A antibody inpatients III6 and II8 revealed faint staining of neuronal

cytoplasm including its axons and dendrites not different toNDCs or to patients with FTLD-TDP type AB or AD pa-thology (data not shown)

Next we investigated TUBA4A protein abundance in theR105C carriers to explore a possible haploinsufficient effectWestern blots measuring TUBA4A abundance were per-formed using temporal cortex tissue of patients II8 and III65 unrelated NDCs 2 patients with FTD with a pathogenicvariant in GRN and TDP type A pathology and 2 patientswith AD (figure 3) In both patients protein levels were sig-nificantly lower compared with healthy controls and patientswith AD In comparison with FTD-GRN patient II6 showeda significant decrease (p value 0002) whereas a decreasedtrend was observed in patient III8 (p value 020)

Microtubule Repolymerization andIntegrity AssaysTo examine whether microtubule behavior is affected by theidentified R105C variant WT and R105C proteins wereexpressed in transfected cells Transfection of the R105Cmutant did not cause adverse effects in terms of cell viabilityand did not significantly alter microtubule integrity (figuree-2 AndashC linkslwwcomNXGA426) The ALS-associatedvariant R320C did show a mild effect on microtubule in-tegrity consistent with previous results25 To compare theability of cells to recover after transient microtubule de-polymerization transfected cells were exposed to a high dose

Figure 3 Immunoblotting Showing a Decreased Trend of TUBA4A Protein Abundance in Patients

(A) Protein was extracted for immunoblotting from temporalcortex tissues of 2 patients (III6 and II8) 2 patients with FTLD-TDP type A caused by a pathogenic GRN variant (GRN) 2 pa-tients with Alzheimer disease (AD) and 5 NDCs Blots wereperformed in technical duplicates and normalized to thehousekeeping gene GAPDH Immunoblots are shown of thefirst isolation with technical duplicates of TUBA4A (B) Therelative TUBA4A protein abundance of biological triplicateswas normalized to the mean abundance of the 5 NDCs Avisible trend is observed of decreased TUBA4A protein levelsin patients compared with NDCs and disease controls al-though a high degree of variation exits among NDCs III6 vsNDC p = 0005 III6 vs AD p lt 0001 III6 vs GRN p = 0002 II8vs NDC p = 003 II8 vs AD p = 0002 II8 vs GRN p = 020(unpaired t tests) FTLD-TDP = frontotemporal lobar de-generation with TDP pathology GAPDH = glyceraldehyde-3-phosphate dehydrogenase


of nocodazole to completely depolymerize all microtubules(figure e-3) and subsequently allowed to recover for varioustime points on nocodazole washout Antindashβ-tubulin stainingof the microtubule network shows that both R105C- andR320-transfected cells recovered normally with regrowth ofendogenous microtubules (figure 4) However after 10 mi-nutes only 30 of R105C-transfected cells and 20 ofcells containing R320C showed incorporation of mutantTUBA4A into newly formed microtubules significantly lowerthan WT (p lt 005) These results indicate that the R105Cvariant at least partially disrupts tubulin function preventingincorporation of the mutant protein into microtubules

DiscussionIn this study we demonstrate segregation of a likely patho-genic TUBA4A variant in a family with FTD without con-comitant ALS The clinical picture of this family is relativelyheterogeneous although all patients had a symptom onset

before age 70 years FTLD-TDP pathology was confirmed in2 patients resembling FTLD-TDP type A

Despite the clear autosomal dominant inheritance pattern theclinical presentation in this family is distinct from the typicalgenetic variants associated with FTD no concomitant ALS orneuropsychiatric symptoms such as in C9orf72 carriers norepetitivestereotyped behaviors or semantic impairment asoften observed in MAPT carriers and no nonfluent aphasiawhich is associated with GRN variants27 Instead several pa-tients presented with bvFTD with prominent disinhibitedbehavior and parkinsonian-like gait disturbances One patienthad unspecified dementia and concomitant parkinsonism andanother relative was clinically diagnosed with PD Parkin-sonism is a common clinical presentation of FTD and hasbeen observed in up to 387 of patients with FTD2829

Various motor symptoms can be seen in patients with FTDoften including bradykinesia followed by parkinsonian gaitand postural instability The symptoms are typically un-responsive to levodopa as with our patient28 Of interest 1

Figure 4 Microtubule Repolymerization Assay Showing Cells After 10 Minutes of Nocodazole Washout

The arrows indicate neuronal inclusions anddystrophic neurites immunoreactive to P62 (A)and pTDP-43 (B) (A) COS1 cells were trans-fected either with hemagglutinin (HA)-taggedwild-type (WT) tubulin R105C or R320Cmutantconstructs and exposed to high dose of noco-dazole to completely depolymerize all micro-tubules We studied the repolymerizationpotential of microtubules at 0 5 10 and 30minutes following nocodazole washout Thecells were stained to visualize endogenous tu-bulin with anti-β-tubulin (green) and the con-structs using anti-HA antibody (red) Magnifiedinsets show the cellular area where the cen-trosome is located as indicated by the arrowsAt the 0minute time point the centrosomes areabsent (figure e-3 linkslwwcomNXGA426)yet each time point thereafter shows an in-crease of cells with visible centrosome andnewly formed microtubules The images showexamples of cells fixed after 10 minutes (Baand Bb) The graphs below depict the quanti-fied fraction of cells with recovered microtu-bules at the different time points Neither of the2 mutant tubulins significantly affect recoveryof the microtubule network (antindashβ-tubulinBa) but both mutants do not incorporate effi-ciently into the newly formed microtubulenetwork (anti-HA Bb) Anti-HA at 10-minuterecovery WT vs R105C p lt 005 WT vs R320C plt 0001 Anti-HA at 30 minute recovery WT vsR105C p lt 001WT vs R320C plt 001 (unpairedt tests) Scale bar 10 μm


previously reported patient with FTD with the pArg64-Glyfs90 variant in TUBA4A exhibited an inexhaustible gla-bellar reflex and stooped posture with decreased arm swing30

The father and grandmother of this patient had PDwith onsetlt65 years These observations support that TUBA4A variantsmay be associated with FTD with parkinsonism as apparentin the currently described family although additional reportsare required to confirm this

We describe 2 neuropathologic cases associated with a likelypathogenic variant in TUBA4A largely consistent withFTLD-TDP pathology type A Genetically this subtype isusually associated with pathogenic variants in GRN17 How-ever we did not find any pathogenic variant in GRN TheTDP pathology in our patients was most prominent in thetemporal cortex marked by the presence of neuronal inclu-sions and short dystrophic neurites mainly in the superficiallayers Compared with FTLD-TDP caused by a GRN path-ogenic variant the number of inclusions was somewhat lowerand glial inclusions were absent This is in line with a previousstudy where cases without GRN mutations were associatedwith fewer TDP-43 neurons and neurites compared withmutation carriers31 Additional neuropathologic studies ofpatients with FTD with TUBA4A variants are needed forfurther characterization and we urge others to consider ge-netic testing of TUBA4A in similar pathologic cases withunknown genetic defect

The causal role of the TUBA4A R105C variant in this family issupported by familial segregation with disease and the prioridentification of likely pathogenic TUBA4A variants in pa-tients with ALS and FTD R105C is located in a highly con-served codon and its pathogenicity is supported by insilico predictions The variant is absent in GnomAD and theregion is intolerant to genetic variation (overall missenseZ score 33)

TUBA4A encodes an α-tubulin subunit which together withβ-tubulin constitutes the tubulin heterodimer the buildingblock of microtubules32 Mutations in both α- and β-tubulinencoding genes are associated with brain abnormalities andcompromised microtubule function has often been linked toneurodegeneration32-34 ALS-associated TUBA4A variantsare suggested to dysregulate neuronal function by disrup-tion of microtubule dynamics and stability25 No evidenceof TUBA4A variant segregation has yet been demonstratedin extended FTD andor ALS families In figure 5 and tablee-2 (linkslwwcomNXGA426) we provide an overviewof all currently reported candidate variants Eight TUBA4Avariants were initially associated with familial ALS withfunctional assays supporting pathogenicity of at least 5variants2535 One ALS patient with a TUBA4A variant had afirst-degree relative with FTD When analyzing a cohort ofpatients with sporadic ALS the authors found 4 novelheterozygous variants with a possibly damaging effect36

The first TUBA4A variant in FTD without ALS was iden-tified in a Belgian patient diagnosed with semantic de-mentia30 This frameshift variant (pArg64Glyfs90)occurred in exon 2 leading to a truncated protein Familyhistory was positive for PD and cognitive impairmentHowever segregation analysis was not performed The lackof familial segregation neuropathologic confirmation andlow incidence of likely pathogenic variants in TUBA4A hasleft the significance of TUBA4A variants on ALS and FTDdisease risk uncertain37-39

Based on different microtubule-based assays we demonstratethat the novel variant R105C behaves similar though notidentical to the ALS-associated variant R320C25 Our resultsclearly indicate that R105C mutant tubulin does not in-corporate efficiently into repolymerizing microtubules similarto R320C The incorporation of endogenous tubulin is notaffected as shown by overall intact microtubule integrity and

Figure 5 Schematic Representation of the TUBA4A Protein Structure With Identified and Previously Reported Variants

The genetic variants in TUBA4A are organized according to clinical phenotype revealing that all variants associated with FTD or ALS-FTD are located in theGTPase domain Themajority of the variants found in ALS patients are localized in exon 4 in the C-terminal domain For 1 variant (V7I) the phenotypewas notdescribed The R015C variant identified in this study (red box) is the only variant located in exon 3 Underlined variants positive family history for dementiabold variants functional assay supporting variant ALS = amyotrophic lateral sclerosis FTD = frontotemporal dementia Additional details for each variant canbe found in table e-2 (linkslwwcomNXGA426)


repolymerization potential Immunoblots in postmortembrain tissue showed a trend of decreased TUBA4A proteinabundance in TUBA4A carriers compared with healthy anddisease controls suggesting that the mutant protein may bemore susceptible for degradation The absence of alteredTUBA4A staining in our 2 patients indicates that R105Ctubulin does not lead to formation of TUBA4A aggregatesTogether these data suggest that the R105C variant mayaffect the ability of TUBA4A to assemble into growing fila-ments but once the filaments are formed their stability is notaltered Additional experiments will be required to shed morelight on the molecular mechanisms underlying the effects ofthe R105C variant on tubulin synthesisturnover and on thestructure of the neuronal microtubule network ultimatelyaffecting neuronal functioning

Previous experiments demonstrated that ALS-associatedTUBA4A variants destabilize the microtubule network withvariable penetrance depending on the specific mutant25 Thetruncating variant W407X located at the C-terminus yieldedthe most profound effect dependent on aggregation of themutant protein Missense variants located upstream (R320Cand A383T) showed a different and somewhat less severeimpact Two variants were identified in patients with ALS-FTD R215C resulted in a milder effect on microtubule sta-bility whereas no differences were detected for G43V Thesevariants are located in the GTPase domain instead of theC-terminus similar to R105C (figure 5) The variable effectsof variants in the 2 domains and whether this translates to aspecific constellation of phenotypes remain to be clarifiedWe hypothesize that variation in the C-terminus of TUBA4Awhich interacts with the kinesin motor domains and otherMAPs is prone to cause or contribute to ALS due to impairedmicrotubule stability andor function The N-terminus andGTPase domains are predominantly involved in proteinfolding and conformation and variants in these domains ap-pear to be more associated with an FTD phenotype or FTDwith concomitant ALS

Further insight may be ascertained from other tubulingenes which have been studied more extensively For ex-ample a combination of defects has been demonstratedfor TUBB3 including altered microtubule dynamics dis-rupted interaction with kinesin motors and reduced het-erodimer formation40 Structural modeling and additionalexperiments are essential to evaluate the functional im-portance of individual TUBA4A domains and to understandhow TUBA4A variation contributes to neurodegenerativedisorders

Although we did not observe motor neuron symptoms in thereported patients we cannot rule out the existence of subtleneurophysiologic changes as EMG was not performed An-other limitation of this study is the small size of the familywhich limited us from performing a classical linkage analysisInstead we used genome-wide genotyping arrays to identifycommon haplotype blocks which complemented our analysis

of the exome sequencing data We distinguished the variant inTUBA4A as most likely cause although we cannot completelyrule out the other 3 shared variants However the observedfunctional impact of the TUBA4A variant supports a patho-genic role

Our data support the contribution of TUBA4A variants toFTD without ALS We provide evidence of familial segre-gation with FTD detailed clinical features of 8 patients andneuropathology of 2 patients with FTD Furthermore wedemonstrate a severe impact of the variant on tubulinfunction Our findings indicate that patients with a likelypathogenic variant in TUBA4A may clinically manifest withbvFTD symptoms possibly including parkinsonism andpathologically resemble FTLD-TDP type A We suggestthat patients with FTD especially with positive family his-tory andor TDP pathology should be screened forTUBA4A variants to further characterize this class of geneticvariants

AcknowledgmentThe authors thank all the patients and their relatives whoparticipated in this study Also they thank the NetherlandsBrain Bank (NBB) for providing the human brain tissues andtheir contributions to the immunohistochemistry

Study FundingThis research was funded by Alzheimer Nederland (WE09-2018-07) and by The Dutch Research Council (NWO)

DisclosureSeveral authors of this publication are members of the Eu-ropean Reference Network for Rare Neurological Diseases(Project ID No 739510) Go to NeurologyorgNG for fulldisclosures

Publication HistoryReceived by Neurology Genetics September 28 2020 Accepted in finalform April 6 2021

Appendix Authors

Name Location Contribution

Merel O MolMD

Department of NeurologyErasmus Medical CenterRotterdam the Netherlands

Draftingrevision of themanuscript for contentincluding medical writingfor content major role inthe acquisition of datastudy concept or designand analysis orinterpretation of data

Tsz H WongMD PhD



Continued


References1 Olney NT Spina S Miller BL Frontotemporal dementia Neurol Clin 201735(2)

339-3742 Beeldman E Raaphorst J Klein Twennaar M de Visser M Schmand BA de Haan RJ

The cognitive profile of ALS a systematic review and meta-analysis update J NeurolNeurosurg Psychiatry 201687(6)611-619

3 Burrell JR Halliday GM Kril JJ et al The frontotemporal dementia-motor neurondisease continuum Lancet 2016388(10047)919-931

4 Rohrer JD Guerreiro R Vandrovcova J et al The heritability and genetics of fron-totemporal lobar degeneration Neurology 200973(18)1451-1456

5 Moore KM Nicholas J Grossman M et al Age at symptom onset and death anddisease duration in genetic frontotemporal dementia an international retrospectivecohort study Lancet Neurol 202019(2)145-156

6 Greaves CV Rohrer JD An update on genetic frontotemporal dementia J Neurol2019266(8)2075-2086

7 Mathis S Goizet C Soulages A Vallat JM Masson GL Genetics of amyotrophiclateral sclerosis a review J Neurol Sci 2019399217-226

8 Nguyen HP Van Broeckhoven C van der Zee J ALS genes in the genomic era andtheir implications for FTD Trends Genet 201834(6)404ndash423

9 Ferrari R Manzoni C Hardy J Genetics and molecular mechanisms of fronto-temporal lobar degeneration an update and future avenues Neurobiol Aging20197898-110

10 Blauwendraat C Wilke C Simon-Sanchez J et al The wide genetic landscape ofclinical frontotemporal dementia systematic combined sequencing of 121 consecu-tive subjects Genet Med 201820(2)240-249

11 Ramos EM Koros C Dokuru DR et al Frontotemporal dementia spectrum firstgenetic screen in a Greek cohort Neurobiol Aging 201975224e1-224e8

12 Dols-Icardo O Garcia-Redondo A Rojas-Garcia R et al Analysis of known amyo-trophic lateral sclerosis and frontotemporal dementia genes reveals a substantial ge-netic burden in patients manifesting both diseases not carrying the C9orf72 expansionmutation J Neurol Neurosurg Psychiatry 201889(2)162-168

13 Mol MO van Rooij JGJ Wong TH et al Underlying genetic variation in familialfrontotemporal dementia sequencing of 198 patients Neurobiol Aging 202097148e9-148e16

14 Ramos EM Dokuru DR Van Berlo V et al Genetic screening of a large series ofNorth American sporadic and familial frontotemporal dementia cases AlzheimersDement 202016(1)118-130

15 Rascovsky K Hodges JR Knopman D et al Sensitivity of revised diagnosticcriteria for the behavioural variant of frontotemporal dementia Brain 2011134(Pt 9)2456-2477

16 van Lier MG Wagner A van Leerdam ME et al A review on the molecular diag-nostics of Lynch syndrome a central role for the pathology laboratory J Cell Mol Med201014(1-2)181-197

17 Neumann M Mackenzie IRA Review neuropathology of non-tau frontotemporallobar degeneration Neuropathol Appl Neurobiol 201945(1)19-40

18 Nykamp K Anderson M Powers M et al Sherloc a comprehensive refinement of theACMG-AMP variant classification criteria Genet Med 201719(10)1105-1117

19 Renton AE Majounie E Waite A et al A hexanucleotide repeat expansion inC9ORF72 is the cause of chromosome 9p21-linked ALS-FTD Neuron 201172(2)257-268

20 Chang CC Data management and summary statistics with PLINK In Dutheil JY edStatistical Population Genomics Springer US 202049-65

21 van der Zwaag PA van Tintelen JP Gerbens F et al Haplotype sharing test mapsgenes for familial cardiomyopathies Clin Genet 201179(5)459-467

22 Wang K Li M Hakonarson H ANNOVAR functional annotation of genetic variantsfrom high-throughput sequencing data Nucleic Acids Res 201038(16)e164

23 Kircher M Witten DM Jain P OrsquoRoak BJ Cooper GM Shendure J A generalframework for estimating the relative pathogenicity of human genetic variants NatGenet 201446(3)310

24 Bulinski JC Gruber D Faire K Prasad P Chang W GFP chimeras of E-MAP-115(ensconsin) domains mimic behavior of the endogenous protein in vitro and in vivoCell Struct Funct 199924(5)313-320

25 Smith BN Ticozzi N Fallini C et al Exome-wide rare variant analysis identifiesTUBA4A mutations associated with familial ALS Neuron 201484(2)324-331

26 Khan K Zech M Morgan AT et al Recessive variants in ZNF142 cause a complexneurodevelopmental disorder with intellectual disability speech impairment seizuresand dystonia Genet Med 201921(11)2532-2542

27 Snowden JS Adams J Harris J et al Distinct clinical and pathological phenotypes infrontotemporal dementia associated with MAPT PGRN and C9orf72 mutationsAmyotroph Lateral Scler Frontotemporal Degener 201516(7-8)497-505

28 Baizabal-Carvallo JF Jankovic J Parkinsonism movement disorders and genetics infrontotemporal dementia Nat Rev Neurol 201612(3)175-185

29 Park HK Park KH Yoon B et al Clinical characteristics of parkinsonism in fronto-temporal dementia according to subtypes J Neurol Sci 201737251-56

30 Perrone F Nguyen HP Van Mossevelde S et al Investigating the role of ALS genesCHCHD10 and TUBA4A in Belgian FTD-ALS spectrum patients Neurobiol Aging201751177e9-177e16

31 Mao Q Zheng X Gefen T et al FTLD-TDP with and without GRNmutations causedifferent patterns of CA1 pathology J Neuropathol Exp Neurol 201978(9)844-853

32 Dubey J Ratnakaran N Koushika SP Neurodegeneration and microtubule dynamicsdeath by a thousand cuts Front Cell Neurosci 20159343

Appendix (continued)


ShamiramMelhem MSc


Major role in theacquisition of data andanalysis or interpretationof data

Sreya BasuPhD

Department of Cell BiologyErasmus Medical CenterRotterdam the Netherlands

Draftingrevision of themanuscript for contentincluding medical writingfor content major role inthe acquisition of data andanalysis or interpretation ofdata

RiccardoViscusi MSc


Major role in the acquisitionof data

Niels GaljartPhD



AnnemiekeJMRozemullerMD PhD

Department of PathologyAmsterdam UniversityMedical Center LocationVUmc AmsterdamNeuroscience theNetherlands

Major role in the acquisitionof data and analysis orinterpretation of data

ClaudiaFallini PhD

Department of Cell andMolecular BiologyUniversity of Rhode IslandKingston


John ELanders MDPhD

Department of NeurologyUniversity of MassachusettsMedical School Worcester

Draftingrevision of themanuscript for contentincluding medical writingfor content and analysis orinterpretation of data

Laura DonkerKaat MD PhD


Draftingrevision of themanuscript for contentincluding medical writingfor content and studyconcept or design

Harro SeelaarMD PhD



JeroenGJ vanRooij PhD



John C vanSwieten MDPhD




33 Tischfield MA Cederquist GY Gupta ML Jr Engle EC Phenotypic spectrum of thetubulin-related disorders and functional implications of disease-causing mutationsCurr Opin Genet Dev 201121(3)286-294

34 Baird FJ Bennett CL Microtubule defects amp neurodegeneration J Genet Syndr GeneTher 20134203

35 Clark JA Yeaman EJ Blizzard CA Chuckowree JA Dickson TC A case for micro-tubule vulnerability in amyotrophic lateral sclerosis altered dynamics during diseaseFront Cell Neurosci 201610204

36 Pensato V Tiloca C Corrado L et al TUBA4A gene analysis in sporadic amyotrophiclateral sclerosis identification of novel mutations J Neurol 2015262(5)1376-1378

37 Rademakers R van Blitterswijk M Excess of rare damaging TUBA4A variants sug-gests cytoskeletal defects in ALS Neuron 201484(2)241-243

38 Dols-Icardo O Iborra O Valdivia J et al Assessing the role of TUBA4A gene infrontotemporal degeneration Neurobiol Aging 201638215e3-215e4

39 Li J He J Tang L Chen L Ma Y Fan D Screening for TUBA4A mutations in a largeChinese cohort of patients with ALS re-evaluating the pathogenesis of TUBA4A inALS J Neurol Neurosurg Psychiatry 201889(12)1350-1352

40 Tischfield MA Baris HN Wu C et al Human TUBB3 mutations perturb mi-crotubule dynamics kinesin interactions and axon guidance Cell 2010140(1)74-87


DOI 101212NXG000000000000059620217 Neurol Genet

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is an official journal of the American Academy of Neurology Published since April 2015 it isNeurol Genet

Frontotemporal dementia (FTD) is a common type of early-onset dementia characterized by behavioral changes andcognitive impairment1 Up to 15 of patients developcomorbid amyotrophic lateral sclerosis (ALS)2 Because ofoverlap in clinical genetic and pathologic features both dis-orders are now considered part of a disease continuum3

Around a third of patients with FTD have a strong familyhistory although heritability is highly variable across sub-types4 The behavioral variant (bvFTD) is the most com-monly inherited form (45) followed by FTD withconcomitant motor neuron disease (FTD-MND) In con-trast most patients with a language variant (primary pro-gressive aphasia) are sporadic The majority of familial FTD iscaused by pathogenic changes in MAPT GRN or C9orf72Each genetic subtype accounts for5ndash10 of all FTD butgeographical variability is evident such as high occurrence ofGRN variants in Southern Europe5 Genetic forms of ALSrepresent approximately 5ndash10 of the total number of pa-tients with ALS67 Worldwide the C9orf72 repeat expansionis the most frequent cause of familial FTD and by far the mostcommon cause of familial ALS (30)7 Less prevalentvariants causing FTD andor ALS have been identified in gt10other genes such as TARDBP TBK1 VCP and TUBA4A89

Despite these rapid advances in the genetic architecture ofFTD many studies describe a subset of familial patientswithout identified genetic defect10-14 This suggests the exis-tence of yet undiscovered genes playing a role in the patho-genesis of FTD

In this study we describe the clinical and neuropathologicpresentation of a family with autosomal dominant FTD andpreviously unknown genetic defect Genetic analyses revealeda novel TUBA4A variant segregating with disease Additionalfunctional experiments strengthen the likely pathogenic roleof TUBA4A variants in FTD

MethodsAscertainment of PatientsWe studied 8 patients with dementia (onset le70 years) in aDutch family across 2 generations Three patients (II8 III6and III8) were clinically diagnosed with bvFTD by the in-vestigators according to international consensus criteria(figure 1)15 One patient (III5) had unspecified dementiawith parkinsonism as clinically determined by the investiga-tors The remaining 4 patients were diagnosed with

unspecified dementia or Parkinson disease (PD) before thisstudy (II1 II2 II3 and III1) As these 4 patients weredeceased further clinical data were collected by interviewingrelatives and reviewing medical records from hospitals ornursing homes In addition a relative with clinical late-onsetAlzheimer disease (LOAD II9) and 2 unaffected relatives(III2 and III12) were included Blood-derived DNA wasobtained from all 3 patients clinically diagnosed with bvFTD1 patient with unspecified dementia (III5) the relative af-fected by LOAD and the 2 unaffected relatives For a secondpatient with unspecified dementia (III1) DNA was extractedfrom formalin-fixed paraffin-embedded lymph node tissue aspreviously described16 Brain autopsy was performed in 2patients with bvFTD (II8 and III6) and confirmed the di-agnosis frontotemporal lobar degeneration (FTLD) Neuro-pathology was not available from the other deceased patients

Histology and ImmunohistochemistryNeuropathology was available from 2 patients clinically di-agnosed with bvFTD (II8 and III6) Brain autopsy was per-formed by the Netherlands Brain Bank (NBB) within 8 hoursafter death Routine immunohistochemistry was also performedby the NBBWe performed additional staining onmultiple brainregions including all cortical areas hippocampus and caudateputamen The following antibodies were used p62 (Lck Ligand610833 1100 BD Transduction Laboratories Franklin LakesNJ) Phospho-Tau (Ser202 Thr205) Monoclonal AntibodyAT8 (MN1020 1400 Thermo Fisher Scientific WalthamMA) Purified anti-β-Amyloid (4G8 800701 11000 BioL-egend SanDiego CA) and pTDP-43 (CAC-TIP-PTD-M01 11000 Cosmo Bio Carlsbad CA) The pattern of TDP-43 pa-thology was classified into subtypes according to the morphol-ogy and distribution of neuronal inclusions as proposed byNeumann et al17

Genetic AnalysesWe performed Sanger sequencing and repeat-primed PCR in2 patients with bvFTD (II8 and III6) to exclude a patho-genic or likely pathogenic variant in MAPT and GRN(according to the American College of Medical Genetics andGenomics guidelines)18 or a hexanucleotide repeat expansionin C9orf72 (gt30 repeats regarded as pathogenic)19

All 3 patients with bvFTD and 1 patient with unspecifieddementia (III5) were genotyped using Infinium GlobalScreening Array-24 v30 (Illumina San Diego CA) accordingto the manufacturerrsquos protocols Genotypes were called usingGenomeStudio 20 and quality control was performed using

GlossaryALS = amyotrophic lateral sclerosis bvFTD = behavioral variant FTDCADD =Combined Annotation-Dependent DepletionFTD = frontotemporal dementia FTD-MND = FTD with concomitant motor neuron disease FTLD = frontotemporal lobardegeneration GAPDH = glyceraldehyde-3-phosphate dehydrogenase GnomAD = Genome Aggregation Database HA =hemagglutinin LOAD = late-onset Alzheimer diseaseNBB = Netherlands Brain BankNCI = neuronal cytoplasmic inclusionNII = neuronal intranuclear inclusion PD = Parkinson disease TDP-43 = TAR DNA binding protein 43 WT = wild type



















Age atdeath y

Diseaseduration y

Clinicaldiagnosis

Clinicalsymptoms












NA Heterozygous
















































Appendix Authors


Merel O MolMD



Tsz H WongMD PhD



Continued





































ShamiramMelhem MSc



Sreya BasuPhD



RiccardoViscusi MSc



Niels GaljartPhD






ClaudiaFallini PhD



John ELanders MDPhD






Harro SeelaarMD PhD


































Reprints





















Age atdeath y

Diseaseduration y

Clinicaldiagnosis

Clinicalsymptoms












NA Heterozygous
















































Appendix Authors


Merel O MolMD



Tsz H WongMD PhD



Continued





































ShamiramMelhem MSc



Sreya BasuPhD



RiccardoViscusi MSc



Niels GaljartPhD






ClaudiaFallini PhD



John ELanders MDPhD






Harro SeelaarMD PhD


































Reprints

















































Appendix Authors


Merel O MolMD



Tsz H WongMD PhD



Continued





































ShamiramMelhem MSc



Sreya BasuPhD



RiccardoViscusi MSc



Niels GaljartPhD






ClaudiaFallini PhD



John ELanders MDPhD






Harro SeelaarMD PhD


































Reprints







































ShamiramMelhem MSc



Sreya BasuPhD



RiccardoViscusi MSc



Niels GaljartPhD






ClaudiaFallini PhD



John ELanders MDPhD






Harro SeelaarMD PhD


































Reprints




























Reprints




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