Frontotemporal Dementia Research Articles

Elevated VCP ATPase Activity Correlates With Disease Onset in Multisystem Proteinopathy-1.

Multisystem proteinopathy-1 (MSP1) is a late onset disease with >50 pathogenic variants in p97/VCP. MSP1 patients have multiple phenotypes that include inclusion body myopathy, Paget disease of the bone, amyotrophic lateral sclerosis, and frontotemporal dementia. There have been no clear genotype-phenotype correlations. We sought to identify genotype-phenotype correlations and associate these with VCP intrinsic ATPase activity. Patients with MSP1 were identified from the literature and the Cure VCP patient registry. Age at onset and at loss of ambulation were collated. VCP intrinsic ATPase activity was evaluated from recombinant purified protein. Among the 5 most common pathogenic VCP variants in MSP1 patients, R155C patients had the earliest average age at onset (38.15±9.78). This correlated with higher ATPase activity. Evaluation of 5 variants confirmed an inverse correlation between age at onset and ATPase activity (r = -0.94, p = 0.01). Previous studies have reported that VCP pathogenic variants are "hyperactive." Whether this elevation in VCP ATPase activity is relevant to disease is unclear. Our study supports that in vitro VCP activity correlates with disease onset and may guide the prognosis of patients with rare or unreported variants. Moreover, it suggests that inhibition of VCP ATPase activity in MSP1 may be therapeutic.

Polyconnectomic scoring of functional connectivity patterns across eight neuropsychiatric and three neurodegenerative disorders

BackgroundNeuropsychiatric and neurodegenerative disorders involve diverse changes in brain functional connectivity. As an alternative to approaches searching for specific mosaic patterns of affected connections and networks, we used polyconnectomic scoring to quantify disorder-related whole-brain connectivity signatures into interpretable, personalized scores. MethodsThe polyconnectomic score (PCS) measures the extent to which an individual's functional connectivity (FC) mirrors the whole-brain circuitry characteristics of a trait. We computed PCS for eight neuropsychiatric conditions (attention-deficit/hyperactivity disorder, anxiety-related disorders, autism spectrum disorder, obsessive-compulsive disorder, bipolar disorder, major depressive disorder, schizoaffective disorder, and schizophrenia) and three neurodegenerative conditions (Alzheimer's disease, frontotemporal dementia, and Parkinson’s disease) across 22 datasets with resting-state functional MRI of 10,667 individuals (5,325 patients, 5,342 controls). We further examined PCS in 26,673 individuals from the population-based UK Biobank cohort. ResultsPCS was consistently higher in out-of-sample patients across six of the eight neuropsychiatric and across all three investigated neurodegenerative disorders ([min, max]: AUC = [0.55, 0.73], pFDR = [1.8 x 10-16, 4.5 x 10-2]). Individuals with elevated PCS levels for neuropsychiatric conditions exhibited higher neuroticism (pFDR < 9.7 x 10-5), lower cognitive performance (pFDR < 5.3 x 10-5), and lower general wellbeing (pFDR < 9.7 x 10-4). ConclusionsOur findings reveal generalizable whole-brain connectivity alterations in brain disorders. PCS effectively aggregates disorder-related signatures across the entire brain into an interpretable, subject-specific metric. A toolbox is provided for PCS computation.

Perceptual and semantic deficits in face recognition in semantic dementia

State of the artSemantic dementia (SD) patients including semantic variant primary progressive aphasia (svPPA) and semantic behavioral variant frontotemporal dementia (sbvFTD) patients show semantic difficulties identifying faces and known people related to right anterior temporal lobe (ATL) atrophy. However, it remains unclear whether they also have perceptual deficits in face recognition. MethodologyWe selected 74 SD patients (54 with svPPA and predominant left ATL atrophy and 20 with sbvFTD and predominant right ATL atrophy) and 36 cognitively healthy controls (HC) from UCSF Memory and Aging Center. They underwent a perceptual face processing test (Benton facial recognition test-short version; BFRT-S), and semantic face processing tests (UCSF Famous people battery – Recognition, Naming, Semantic associations – pictures and words subtests), as well as structural magnetic resonance imaging (MRI). Neural correlates with the task’s performance were conducted with a Voxel-based morphometry approach using CAT12. ResultssvPPA and sbvFTD patients were impaired on all semantic face processing tests, with sbvFTD patients performing significantly lower on the famous faces’ recognition task in comparison to svPPA, and svPPA performing significantly lower on the naming task in comparison to sbvFTD. These tasks predominantly correlated with gray matter (GM) volumes in the right and left ATL, respectively. Compared to HC, both svPPA and sbvFTD patients showed preserved performance on the perceptual face processing test (BFRT-S), and performance on the BFRT-S negatively correlated with GM volume in the right posterior superior temporal sulcus (pSTS). ConclusionOur results suggest that early in the disease, with the atrophy mostly restricted to the anterior temporal regions, SD patients do not present with perceptual deficits. However, more severe SD cases with atrophy in right posterior temporal regions might show lower performance on face perception tests, in addition to the semantic face processing deficits. Early sparing of face perceptual deficits in SD patients, regardless of hemispheric lateralization, furthers our understanding of clinical phenomenology and therapeutical approaches of this complex disease.

Non-Alzheimer's amnestic mild cognitive impairment with medial temporal hypometabolism.

The increasing use of Alzheimer's disease (AD) biomarkers has led to the recognition of a subgroup of non-AD amnestic mild cognitive impairment (aMCI) patients who have medial temporal hypometabolism on fluorodeoxyglucose-positron emission tomography (FDG-PET). In this academic memory-clinic-based consecutive series, 16 non-AD aMCI patients and 28 AD controls matched for sex, age, and baseline Mini-Mental State Examination (MMSE) were followed for a median duration of 4.5 years. Our primary outcome was the MMSE decline rate over the subsequent years. We also determined the final diagnosis over time. FDG-PET showed more pronounced medial temporal hypometabolism in non-AD cases and more inferior parietal lobule hypometabolism in AD controls. MMSE decline was slower in non-AD (β=-0.51) than in AD (β=-2.00) patients. Five non-AD cases developed frontotemporal dementia years after symptom onset, and one developed dementia with Lewy bodies. Non-AD aMCI patients with medial temporal hypometabolism show slower cognitive decline. Non-AD aMCI with medial temporal hypometabolism shows slower cognitive decline than AD.FDG-PET revealed distinct metabolic patterns between non-AD aMCI and AD patients.Approximately one-third of non-AD aMCI cases developed frontotemporal dementia.Comprehensive diagnostic biomarkers are crucial for non-AD aMCI characterization.

Identification of Potential Causal Genes for Neurodegenerative Diseases by Mitochondria-Related Genome-Wide Mendelian Randomization.

Current research lacks comprehensive investigations into the potential causal link between mitochondrial-related genes and the risk of neurodegenerative diseases (NDDs). We aimed to identify potential causative genes for five NDDs through an examination of mitochondrial-related gene expression levels. Through the integration of summary statistics from expression quantitative trait loci (eQTL) datasets (human blood and brain tissue), mitochondrial DNA copy number (mtDNA-CN), and genome-wide association studies (GWAS) datasets of five NDDs from European ancestry, we conducted a Mendelian randomization (MR) analysis to explore the potential causal relationship between mitochondrial-related genes and Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Lewy body dementia (LBD). Sensitivity analysis and Bayesian colocalization were employed to validate this causal relationship. Through MR analysis, we have identified potential causal relationships between 12 mitochondria-related genes and AD, PD, ALS, and FTD overlapping with motor neuron disease (FTD_MND) in human blood or brain tissue. Bayesian colocalization analysis further confirms 9 causal genes, including NDUFS2, EARS2, and MRPL41 for AD; NDUFAF2, MALSU1, and METTL8 for PD; MYO19 and MRM1 for ALS; and FASTKD1 for FTD_MND. Importantly, in both human blood and brain tissue, NDUFS2 exhibits a significant pathogenic effect on AD, while NDUFAF2 demonstrates a robust protective effect on PD. Additionally, the mtDNA-CN plays a protected role in LBD (OR = 0.62, p = 0.031). This study presents evidence establishing a causal relationship between mitochondrial dysfunction and NDDs. Furthermore, the identified candidate genes may serve as potential targets for drug development aimed at preventing NDDs.

Classification of Alzheimer’s Disease and Frontotemporal Dementia Using Electroencephalography to Quantify Communication between Electrode Pairs

Accurate diagnosis of dementia subtypes is crucial for optimizing treatment planning and enhancing caregiving strategies. To date, the accuracy of classifying Alzheimer’s disease (AD) and frontotemporal dementia (FTD) using electroencephalogram (EEG) data has been lower than that of distinguishing individuals with these diseases from healthy elderly controls (HCs). This limitation has impeded the feasibility of a cost-effective differential diagnosis for the two subtypes in clinical settings. This study addressed this issue by quantifying communication between electrode pairs in EEG data, along with demographic information, as features to train machine learning (support vector machine) models. Our focus was on refining the feature set specifically for AD-FTD classification. Using our initial feature set, we achieved classification accuracies of 76.9% for AD-HC, 90.4% for FTD-HC, and 91.5% for AD-FTD. Notably, feature importance analyses revealed that the features influencing AD-HC classification are unnecessary for distinguishing between AD and FTD. Eliminating these unnecessary features improved the classification accuracy of AD-FTD to 96.6%. We concluded that communication between electrode pairs specifically involved in the neurological pathology of FTD, but not AD, enables highly accurate EEG-based AD-FTD classification.

Nut consumption is associated with a lower risk of all-cause dementia in adults: a community-based cohort study from the UK Biobank.

This cohort study aimed to analyze the relationship between nut consumption and the risk of all-cause dementia in adults from the United Kingdom (UK). Data from participants in the UK Biobank cohort between 2007-2012 (baseline) and 2013-2023 (follow-up) were analyzed. Baseline information on nut consumption was obtained using the Oxford WebQ 24-h questionnaire. All-cause dementia (i.e. Alzheimer's disease, frontotemporal dementia, or vascular dementia) was assessed at baseline and follow-up through self-reported medical diagnosis, hospitalization, or death records. Hazard regression models were used to estimate the association between nut consumption and the risk of developing all-cause dementia, with adjustments made for sociodemographic, lifestyle, hearing problems, self-rated health, and the number of chronic diseases. Participants with all-cause dementia at baseline were excluded. A total of 50,386 participants (mean age 56.5 ± 7.7years, 49.2% women) were included in the prospective analyses. The incidence of all-cause dementia was 2.8% (n = 1422 cases). Compared with no consumption, daily nut consumption (> 0 to 3 or more handfuls) was significantly associated with a 12% lower risk of all-cause dementia (hazard ratio = 0.88; 95% confidence interval, 0.77-0.99) after 7.1 mean years of follow-up, regardless of the potential confounders considered. No statistically significant interactions were observed between nut consumption and any of the covariates included in the hazard regression models. Stratified analyses revealed that nut consumption of up to 1 handful of 30g/day and consumption of unsalted nuts were associated with the greatest protective benefits. The daily consumption of nuts may play a protective role in the prevention of dementia.

Plasma extracellular vesicle: a novel biomarker for neurodegenerative disease diagnosis

Extracellular vesicles (EVs) are membrane-bound structures that carry proteins, lipids, RNA, and DNA, playing key roles in cell communication and material transport. Recent research highlights their potential as disease biomarkers due to their stability in bodily fluids. This study explores using tau and TDP-43 proteins in plasma EVs as diagnostic biomarkers for frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). Analyzing plasma EVs from clinical cohorts, the study found that the 3R/4R tau ratio and TDP-43 levels effectively differentiate between diagnostic groups with high accuracy. Notably, plasma EV biomarkers demonstrate higher diagnostic accuracy and stability compared to direct plasma testing, providing new insights and approaches for future research and clinical practice. Further research is needed to validate these biomarkers in diverse populations and to establish standardized protocols. Future studies should continue to explore the potential of EV biomarkers in a broader range of neurodegenerative diseases and delve deeper into the mechanisms of EV secretion and sorting to enhance their diagnostic utility.

Community Integrated Care Team- Detention Order Outcomes And Indications

Abstract Background Detention orders are the inherent jurisdiction of the high court. Only mechanism to support treatment in those lacking capacity and refusing care. Considered a last resort. Integrated care for older persons teams (ICPOP) often engage with complex cases who require this intervention. I aim to review detention orders enacted on ICPOP patients within 1 year. Methods Retrospective review of notes on all patients who required a detention order for transfer of care from March 2023- March 2024. Assessing on review patient’s primary diagnosis, expressed wishes, interventions implemented by the ICPOP team to avoid detention and then reasons for detention order and finally patient outcome. Results 7 patients. 6 female. Every patient expressed a wish to remain in their home. All 7 patients had dementia. Implemented interventions included, Medical social work, home care packages, Memory resource and technology room referrals, meals on wheels plus family support groups, and legal supports, ward of court and decision-making representatives. Interventions where however unsuccessful and reasons for detention ranged from- Night-time wandering x3. Road safety concerns x 3. Family neglect and abuse x 3. Fire safety x1 and Accidental poisoning/malnutrition x1 and Alcohol excess x2. All bar one patient settled without need for medication or specialist unit when transferred to nursing home. Conclusion Outcomes were positive in all cases of detention order being implemented. All 7 patients received better care and avoided serious risk to health. The one patient who required significant intervention to maintain transfer was a behavioural fronto-temporal dementia who required a locked unit and psychotropics. In all cases family supported the decision and patient quality of life improved. Where autonomy and liberty remain paramount concerns for all individuals this review confirms that in some cases doctors must act in the best interests of their patients even if this act is against their wishes.

Neuropsychiatric Symptoms Cluster and Fluctuate Over Time in Behavioral Variant Frontotemporal Dementia.

Cognitive and behavioral phenomena define behavioral variant frontotemporal dementia (bvFTD), but neuropsychiatric symptoms (NPS) outside the core criteria are common throughout the illness. Identifying how NPS cluster in bvFTD may clarify the underlying neurobiology of bvFTD-related NPS and guide development of therapies. Participants (N=354) with sporadic and genetic bvFTD were enrolled in the ARTFL LEFFTDS Longitudinal Frontotemporal Lobar Degeneration Consortium. Dementia stage was defined as early (CDR® plus NACC FTLD ≤ 1) or advanced (CDR® plus NACC FTLD ≥ 1). Baseline and annual follow-up visit data were analyzed to compare NPS across stages of bvFTD. Psychiatric states were captured using the Neuropsychiatric Inventory-Questionnaire and Clinician Judgement of Symptoms. Polychoric cluster analysis was used to describe NPS clusters. NPS were highly prevalent (≥ 90%) in early and late bvFTD. Four NPS clusters were identified based on magnitude of factor loadings: affective, disinhibited, compulsive, and psychosis. Neuropsychiatric symptoms fluctuated across visits. In the affective cluster, depression and anxiety showed the least visit-to-visit stability. In the disinhibited cluster, elation showed the least stability. Symptoms in the psychosis and compulsive clusters (hallucinations, delusions, obsessions/compulsions, and hyperorality) were largely stable, persisting from visit-to-visit in more than 50% of cases. NPS in bvFTD are frequent and cluster into four discrete groups in bvFTD. These clusters may result from specific neural network disruptions that could serve as targets for future interventions. The fluctuating nature of NPS in bvFTD suggests that they are not reliable markers of disease progression or stage.

The Microbiota-Gut-Brain Axis and Neurological Disorders: A Comprehensive Review.

Microbes have inhabited the earth for hundreds of millions of years longer than humans. The microbiota-gut-brain axis (MGBA) represents a bidirectional communication pathway. These communications occur between the central nervous system (CNS), the enteric nervous system (ENS), and the emotional and cognitive centres of the brain. The field of research on the gut-brain axis has grown significantly during the past two decades. Signalling occurs between the gut microbiota and the brain through the neural, endocrine, immune, and humoral pathways. A substantial body of evidence indicates that the MGBA plays a pivotal role in various neurological diseases. These include Alzheimer's disease (AD), autism spectrum disorder (ASD), Rett syndrome, attention deficit hyperactivity disorder (ADHD), non-Alzheimer's neurodegeneration and dementias, fronto-temporal lobe dementia (FTLD), Wilson-Konovalov disease (WD), multisystem atrophy (MSA), Huntington's chorea (HC), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS), temporal lobe epilepsy (TLE), depression, and schizophrenia (SCZ). Furthermore, the bidirectional correlation between therapeutics and the gut-brain axis will be discussed. Conversely, the mood of delivery, exercise, psychotropic agents, stress, and neurologic drugs can influence the MGBA. By understanding the MGBA, it may be possible to facilitate research into microbial-based interventions and therapeutic strategies for neurological diseases.

Contactin proteins in cerebrospinal fluid show different alterations in dementias.

The proteins contactin (CNTN) 1-6 are synaptic proteins for which there is evidence that they are dysregulated in neurodegenerative dementias. Less is known about CNTN changes and differences in cerebrospinal fluid (CSF) of dementias, which can provide important information about alterations of the CNTN network and be of value for differential diagnosis. We developed a mass spectrometry-based multiple reaction monitoring (MRM) method to simultaneously determine all six CNTNs in CSF samples using stable isotope-labeled standard peptides. The analytical performance of the method was evaluated for peptide stability, dilution linearity and precision. CNTNs were measured in 82 CSF samples from patients with Alzheimer's disease (AD, n = 19), behavioural variant frontotemporal dementia (bvFTD, n = 18), Parkinson's disease dementia/dementia with Lewy bodies (PDD/DLB, n = 18) and non-neurodegenerative controls (n = 27) and compared with core AD biomarkers. The MRM analysis revealed down-regulation of CNTN2 (fold change (FC) = 0.77), CNTN4 (FC = 0.75) and CNTN5 (FC = 0.67) in bvFTD and CNTN3 (FC = 0.72), CNTN4 (FC = 0.75) and CNTN5 (FC = 0.73) in PDD/DLB compared to AD. CNTN levels strongly correlated with each other in controls (r = 0.73), bvFTD (r = 0.86) and PDD/DLB (r = 0.70), but the correlation was significantly lower in AD (r = 0.41). CNTNs in AD did not show correlation even with core AD biomarkers. Combined use of CNTN1-6 levels increased diagnostic performance of AD core biomarkers. Our data show CNTNs differentially altered in dementias and indicate CNTN homeostasis being selectively dysregulated in AD. The combined use of CNTNs with AD core biomarkers might help to improve differential diagnosis.

Genotype–phenotype correlation of SQSTM1 variants in patients with amyotrophic lateral sclerosis

BackgroundSeveral variants of sequestosome 1 (SQSTM1) were screened in patients with amyotrophic lateral sclerosis (ALS), while the pathogenicity and genotype–phenotype correlation remains unclear.MethodsWe screened variants of SQSTM1 gene in 2011...

A framework for translating tauopathy therapeutics: Drug discovery to clinical trials.

The tauopathies are defined by pathological tau protein aggregates within a spectrum of clinically heterogeneous neurodegenerative diseases. The primary tauopathies meet the definition of rare diseases in the United States. There is no approved treatment for primary tauopathies. In this context, designing the most efficient development programs to translate promising targets and treatments from preclinical studies to early-phase clinical trials is vital. In September 2022, the Rainwater Charitable Foundation convened an international expert workshop focused on the translation of tauopathy therapeutics through early-phase trials. Our report on the workshop recommends a framework for principled drug development and a companion lexicon to facilitate communication focusing on reproducibility and achieving common elements. Topics include the selection of targets, drugs, biomarkers, participants, and study designs. The maturation of pharmacodynamic biomarkers to demonstrate target engagement and surrogate disease biomarkers is a crucial unmet need. HIGHLIGHTS: Experts provided a framework to translate therapeutics (discovery to clinical trials). Experts focused on the "5 Rights" (target, drug, biomarker, participants, trial). Current research on frontotemporal degeneration, progressive supranuclear palsy, and corticobasal syndrome therapeutics includes 32 trials (37% on biologics) Tau therapeutics are being tested in Alzheimer's disease; primary tauopathies have a large unmet need.

Tau accumulation is cleared by the induced expression of VCP via autophagy.

Tauopathy, including frontotemporal lobar dementia and Alzheimer's disease, describes a class of neurodegenerative diseases characterized by the aberrant accumulation of Tau protein due to defects in proteostasis. Upon generating and characterizing a stable transgenic zebrafish that expresses the human TAUP301L mutant in a neuron-specific manner, we found that accumulating Tau protein was efficiently cleared via an enhanced autophagy activity despite constant Tau mRNA expression; apparent tauopathy-like phenotypes were revealed only when the autophagy was genetically or chemically inhibited. We performed RNA-seq analysis, genetic knockdown, and rescue experiments with clinically relevant point mutations of valosin-containing protein (VCP), and showed that induced expression of VCP, an essential cytosolic chaperone for the protein quality system, was a key factor for Tau degradation via its facilitation of the autophagy flux. This novel function of VCP in Tau clearance was further confirmed in a tauopathy mouse model where VCP overexpression significantly decreased the level of phosphorylated and oligomeric/aggregate Tau and rescued Tau-induced cognitive behavioral phenotypes, which were reversed when the autophagy was blocked. Importantly, VCP expression in the brains of human Alzheimer's disease patients was severely downregulated, consistent with its proposed role in Tau clearance. Taken together, these results suggest that enhancing the expression and activity of VCP in a spatiotemporal manner to facilitate the autophagy pathway is a potential therapeutic approach for treating tauopathy.

Socioemotional dysfunction and the greater good: a case study

ABSTRACT Moral cognition has largely been studied via dilemmas in which making a utilitarian choice causes instrumental harm (negative dimension). Studies of utilitarianism link this behavior with socioemotional unresponsiveness. However, there is a positive dimension of utilitarianism in which one sacrifices the good of oneself or close others for the overall welfare. We measured utilitarian choices multidimensionally in a patient with behavioral variant frontotemporal dementia (bvFTD), incorporating dilemmas accounting for negative and positive dimensions. Despite socioemotional deficits our patient was highly utilitarian in the positive, dimension of utilitarianism. This case study challenges the tendency to automatically associate bvFTD with antisocial tendencies.

C9orf72 repeat expansions modify risk for secondary motor and cognitive-behavioral symptoms in behavioral-variant frontotemporal degeneration and amyotrophic lateral sclerosis.

In behavioral-variant frontotemporal degeneration (bvFTD) and amyotrophic lateral sclerosis (ALS), secondary motor or cognitive-behavioral symptoms, respectively, are associated with shorter survival. However, factors influencing secondary symptom development remain largely unexplored. We performed a retrospective evaluation of the entire disease course of individuals with ALS (n=172) and bvFTD (n=69). Only individuals who had neuropathological confirmation of TDP-43 proteinopathy at autopsy or a C9orf72 hexanucleotide repeat expansion were included for analysis. We examined the odds and hazard of secondary symptom development and assessed whether each was modified by the presence of a C9orf72 expansion or initial clinical syndrome. Binary logistic regression and Cox proportional hazard analyses revealed increased odds (OR=4.25 [95% CI 1.97-9.14], p<0.001) and an increased hazard (HR= 4.77 [95% CI 2.33-9.79], p<0.001) for developing secondary symptoms in those with a C9orf72 expansion compared to those without. Initial clinical syndrome (bvFTD or ALS), age at symptom onset, and sex were not associated with development of secondary symptoms. These data highlight the need for clinician vigilance to detect the onset of secondary motor and cognitive-behavioral symptoms in patients carrying a C9orf72 expansion, regardless of initial clinical syndrome. C9orf72 clinical care can be enhanced through coordination between cognitive and neuromuscular clinics.

Prion protein pathology in Ubiquilin 2 models of ALS

Mutations in UBQLN2 cause ALS and frontotemporal dementia (FTD). The pathological signature in UBQLN2 cases is deposition of highly unusual types of inclusions in the brain and spinal cord that stain positive for UBQLN2. However, what role these inclusions play in pathogenesis remains unclear. Here we show cellular prion protein (PrPC) is found in UBQLN2 inclusions in both mouse and human neuronal induced pluripotent (IPSC) models of UBQLN2 mutations, evidenced by the presence of aggregated forms of PrPC with UBQLN2 inclusions. Turnover studies indicated that the P497H UBQLN2 mutation slows PrPC protein degradation and leads to mislocalization of PrPC in the cytoplasm. Immunoprecipitation studies indicated UBQLN2 and PrPC bind together in a complex. The abnormalities in PrPC caused by UBQLN2 mutations may be relevant in disease pathogenesis.

Molecular pathology, developmental changes and synaptic dysfunction in (pre-) symptomatic human C9ORF72-ALS/FTD cerebral organoids

A hexanucleotide repeat expansion (HRE) in C9ORF72 is the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Human brain imaging and experimental studies indicate early changes in brain structure and connectivity in C9-ALS/FTD, even before symptom onset. Because these early disease phenotypes remain incompletely understood, we generated iPSC-derived cerebral organoid models from C9-ALS/FTD patients, presymptomatic C9ORF72-HRE (C9-HRE) carriers, and controls. Our work revealed the presence of all three C9-HRE-related molecular pathologies and developmental stage-dependent size phenotypes in cerebral organoids from C9-ALS/FTD patients. In addition, single-cell RNA sequencing identified changes in cell type abundance and distribution in C9-ALS/FTD organoids, including a reduction in the number of deep layer cortical neurons and the distribution of neural progenitors. Further, molecular and cellular analyses and patch-clamp electrophysiology detected various changes in synapse structure and function. Intriguingly, organoids from all presymptomatic C9-HRE carriers displayed C9-HRE molecular pathology, whereas the extent to which more downstream cellular defects, as found in C9-ALS/FTD models, were detected varied for the different presymptomatic C9-HRE cases. Together, these results unveil early changes in 3D human brain tissue organization and synaptic connectivity in C9-ALS/FTD that likely constitute initial pathologies crucial for understanding disease onset and the design of therapeutic strategies.

CRISPR/Cas13d targeting suppresses repeat-associated non-AUG translation of C9orf72 hexanucleotide repeat RNA.

A hexanucleotide GGGGCC repeat expansion in the non-coding region of the C9orf72 gene is the most common genetic mutation identified in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The resulting repeat RNA and dipeptide repeat proteins from non-conventional repeat translation have been recognized as important markers associated with the diseases. CRISPR/Cas13d, a powerful RNA-targeting tool, has faced challenges in effectively targeting RNA with stable secondary structures. Here we report that CRISPR/Cas13d can be optimized to specifically target GGGGCC repeat RNA. Our results demonstrate that the CRISPR/Cas13d system can be harnessed to significantly diminish the translation of poly-dipeptides originating from the GGGGCC repeat RNA. This efficacy has been validated in various cell types, including induced pluripotent stem cells and differentiated motor neurons originating from C9orf72-ALS patients, as well as in C9orf72 repeat transgenic mice. These findings demonstrate the application of CRISPR/Cas13d in targeting RNA with intricate higher-order structures and suggest a potential therapeutic approach for ALS and FTD.