C9orf72 repeat length might influence clinical sub-phenotypes in dementia patients.

BACKGROUND: C9orf72 repeat expansions have been observed in a wide variety of neurodegenerative disorders. The cut-off between normal and pathogenic alleles is not well established as repeat sizing methods are often semi-quantitative. However, intermediate alleles might influence disease prevalence and phenotype, as seen for other repeat expansion disorders. We aimed to further delineate the prevalence of small, intermediate and expanded C9orf72 alleles and elucidate their potential influence on the disease phenotype. METHODS: DNA derived from patients (n = 1804) and healthy individuals (n = 643) was obtained from multiple collectives in Austria. Genotyping was performed using a two-step PCR assay followed by Southern blotting. RESULTS: 3.4% of clinically diagnosed frontotemporal dementia (FTD; n = 5/147) cases and 0.8% of clinically diagnosed Alzheimer's disease (AD; n = 5/602) cases were carriers of a pathological C9orf72 repeat expansion. A significantly earlier disease onset was detected in expansion carriers compared to non-carriers in the FTD and AD cohorts (median 50 years, range 39-64 vs. median 64 years, range 36-92, p = 0.018 and median 63 years, range 54-71 vs. median 74 years, range 45-92, p = 0.006, respectively). C9orf72 intermediate alleles were significantly associated with cerebellar symptoms (p = 0.0004) and sensory deficits in the dementia cohort (p = 0.01). CONCLUSIONS: C9orf72 repeat expansion carriers showed earlier disease onset compared to non-carriers with clinical diagnosis of FTD and AD. Furthermore, C9orf72 intermediate repeats might modify the phenotypic expression in dementia.

Comparing humoral immune response to SARS-CoV2 vaccines in people with multiple sclerosis and healthy controls: An Austrian prospective multicenter cohort study.

BACKGROUND AND PURPOSE: SARS-CoV2 vaccination is recommended for patients with multiple sclerosis (pwMS), but response may be limited by disease-modifying-treatments (DMTs). The aim of this study was to compare the rates of humoral immune response and safety of SARS-CoV-2 vaccines in pwMS and healthy controls (HCs). METHODS: In this multicenter prospective study on 456 pwMS and 116 HCs, SARS-CoV-2-IgG response was measured 3 months after the first vaccine dose. The primary endpoint was defined as proportion of patients developing antibodies (seroconversion). Secondary endpoints included antibody level, safety and efficacy. RESULTS: Compared to 97.4% in HCs, seroconversion occurred in 96.7% (88/91) untreated pwMS, 97.1% of patients (135/139) on immunomodulatory DMTs and 61.1% (138/226; p < 0.001) on immunosuppressive DMTs. Seroconversion was lowest in patients on antiCD20 monoclonal antibodies (CD20 mAbs; 52.6%) followed by sphingosine-1-phosphate-receptor-modulators (S1PMs; 63.6%). In the S1PM subgroup, seroconversion increased with lymphocyte count (odds ratio [OR] 1.31 per 0.1 G/L; p = 0.035). In pwMS on CD20 mAbs, B-cell depletion decreased seroconversion (OR 0.52; p = 0.038), whereas time since last DMT did not. Safety of SARS-CoV-2 vaccines in pwMS was excellent. CONCLUSIONS: Humoral response to SARS-CoV2 vaccines in pwMS is generally excellent. While reduced by immunosuppressive DMTs, most importantly by B-cell-depleting CD20 mAbs and S1PMs, seroconversion is still expected in the majority of patients. SARS-CoV2 vaccination should be offered to every MS patient.

Clinico-genetic spectrum of limb-girdle muscular weakness in Austria: A multicentre cohort study.

BACKGROUND AND PURPOSE: Hereditary myopathies with limb-girdle muscular weakness (LGW) are a genetically heterogeneous group of disorders, in which molecular diagnosis remains challenging. Our aim was to present a detailed clinical and genetic characterization of a large cohort of patients with LGW. METHODS: This nationwide cohort study included patients with LGW suspected to be associated with hereditary myopathies. Parameters associated with specific genetic aetiologies were evaluated, and we further assessed how they predicted the detection of causative variants by conducting genetic analyses. RESULTS: Molecular diagnoses were identified in 62.0% (75/121) of the cohort, with a higher proportion of patients diagnosed by next-generation sequencing (NGS) than by single-gene testing (77.3% vs. 22.7% of solved cases). The median (interquartile range) time from onset to genetic diagnosis was 8.9 (3.7-19.9) and 17.8 (7.9-27.8) years for single-gene testing and NGS, respectively. The most common diagnoses were myopathies associated with variants in CAPN3 (n = 9), FKRP (n = 9), ANO5 (n = 8), DYSF (n = 8) and SGCA (n = 5), which together accounted for 32.2% of the cohort. Younger age at disease onset (p = 0.043), >10× elevated creatine kinase activity levels (p = 0.024) and myopathic electromyography findings (p = 0.007) were significantly associated with the detection of causative variants. CONCLUSIONS: Our findings suggest that an earlier use of NGS in patients with LGW is needed to avoid long diagnostic delays. We further present parameters predictive of a molecular diagnosis that may help to select patients for genetic analyses, especially in centres with limited access to sequencing.

Concordance of cerebrospinal fluid real-time quaking-induced conversion across the European Creutzfeldt-Jakob Disease Surveillance Network.

BACKGROUND AND PURPOSE: Cerebrospinal fluid (CSF) real-time quaking-induced conversion (RT-QuIC) has a high degree of sensitivity and specificity for the diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) and this has led to its being included in revised European CJD Surveillance Network diagnostic criteria for sCJD. As CSF RT-QuIC becomes more widely established, it is crucial that the analytical performance of individual laboratories is consistent. The aim of this ring-trial was to ascertain the degree of concordance between European countries undertaking CSF RT-QuIC. METHODS: Ten identical CSF samples, seven from probable or neuropathologically confirmed sCJD and three from non-CJD cases, were sent to 13 laboratories from 11 countries for RT-QuIC analysis. A range of instrumentation and different recombinant prion protein substrates were used. Each laboratory analysed the CSF samples blinded to the diagnosis and reported the results as positive or negative. RESULTS: All 13 laboratories correctly identified five of the seven sCJD cases and the remaining two sCJD cases were identified by 92% of laboratories. Of the two sCJD cases that were not identified by all laboratories, one had a disease duration >26 months with a negative 14-3-3, whilst the remaining case had a 4-month disease duration and a positive 14-3-3. A single false positive CSF RT-QuIC result was observed in this study. CONCLUSIONS: This study shows that CSF RT-QuIC demonstrates an excellent concordance between centres, even when using a variety of instrumentation, recombinant prion protein substrates and CSF volumes. The adoption of CSF RT-QuIC by all CJD surveillance centres is recommended.

Atypical astroglial pTDP-43 pathology in astroglial predominant tauopathy.

We observed atypical astrocytic pTDP-43 pathology in astroglial predominant tauopathy.

Co-incidental C9orf72 expansion mutation-related frontotemporal lobar degeneration pathology and sporadic Creutzfeldt-Jakob disease.

BACKGROUND: The C9orf72 hexanucleotide expansion mutation is the most common cause of genetic frontotemporal dementia (FTD), amyotrophic lateral sclerosis (ALS) and combined FTD-ALS. Its underlying neuropathology combines TDP-43 pathology and dipeptide repeat protein (DPR) deposits and may also associate with other neurodegeneration-associated protein aggregates. Herein we present a unique combination of C9orf72 mutation with sporadic Creutzfeldt-Jakob disease (CJD) in a 74-year-old patient with rapidly progressive dementia. METHODS: Detailed neuropathological examination including immunohistochemistry for several proteinopathies. Genetic analysis was conducted by repeat primed polymerase chain reaction (PCR). Furthermore, we analyzed additional C9orf72 mutation carriers for prion-protein (PrP) deposits in brain tissue and screened the cerebellar cortex of other CJD cases for p62/DPR neuronal inclusions to assess the frequency of combined pathologies. RESULTS: Postmortem brain examination of a patient with a rapidly progressive neurological deterioration of 8 months' duration confirmed the diagnosis of CJD. She harbored valine homozygosity at PRNP codon 129. In addition, a frontotemporal lobar degeneration (FTLD)-pattern with TDP-43 protein aggregates and p62+/C9RANT+ positive inclusions along with a high degree of Alzheimer-related pathology (A3B3C3) were identified. The suspected C9orf72 expansion mutation was confirmed by repeat-primed PCR. Screening of 13 C9orf72 cases showed no pathological PrP aggregates and screening of 100 CJD cases revealed no other C9orf72 expansion mutation carriers. CONCLUSION: A combination of a C9orf72 expansion mutation-related FTLD with sporadic CJD in the same patient is rare. While the rarity of both diseases makes this concurrence most likely to be coincidental, questions regarding a potential link between these two neurodegenerative pathologies deserve further studies.

Multiple system aging-related tau astrogliopathy with complex proteinopathy in an oligosymptomatic octogenarian.

The combination of multiple neurodegenerative proteinopathies is increasingly recognized. Together they can potentiate neuronal dysfunction and contribute to complex neurological symptoms. We report an octogenarian female case of multiple extraneural metastases of a rectal carcinoma. She attempted suicide, which ultimately led to cardiorespiratory failure nine days after hospital admission. Apart from the suicide attempt and late-onset depression, other psychiatric or neurological symptoms were not reported. Unexpectedly, histopathologic examination revealed prominent aging-related tau astrogliopathy (ARTAG) of all five types (subpial, subependymal, grey and white matter, and perivascular) affecting cortical and subcortical brain regions. This pathology was associated with intermediate Alzheimer's disease neuropathologic change (A2B2C2 score), cerebral amyloid angiopathy, Lewy body-type α-synuclein proteinopathy (Braak stage 4), and a multiple system transactivation response DNA-binding protein of 43 kDa (TDP-43) proteinopathy also involving the astroglia. In summary, we report a complex and extensive combination of multiple proteinopathies with widespread ARTAG of all five types in a patient who had attempted suicide. Although longitudinal psychometric tests and neuropsychological evaluations were not performed, this report poses the question of thresholds of cognition and pathology load, describes ARTAG affecting unusually widespread brain regions, and supports the notion that complex proteinopathies should be regarded as a frequent condition in the elderly.

[Neuropathology of dementia]. / Neuropathologie der Demenzen.

Dementia is the clinical consequence of various neurological disorders with a multitude of etiologies. Precise knowledge of the underlying pathologies is essential for an accurate treatment of patients and for the development of suitable disease biomarkers. A definite diagnosis of many of the disorders, particularly for neurodegenerative ones, can only be made after a thorough postmortem neuropathological examination. This highlights the importance of performing a brain autopsy and the relevance of a close interaction between clinicians, neuroimaging disciplines and neuropathologists as well as with basic researchers. This article aims to give a brief overview on the neuropathology of dementia focusing on neurodegenerative diseases, to further facilitate interdisciplinary collaboration.

The autophagic marker p62 highlights Alzheimer type II astrocytes in metabolic/hepatic encephalopathy.

Metabolic/hepatic encephalopathy is neuropathologically characterized by the presence of Alzheimer type II astrocytes (AA II) with large and clear nuclear morphology. To date, there is no good immunohistochemical marker to better identify these cells. Here, we assessed cases of hepatic encephalopathy of different etiologies by immunohistochemistry using an anti-p62 antibody. We observed peripheral or diffuse nuclear staining of variable intensity in AA II in all cases but not in normal controls or reactive astrocytes. We conclude that p62 is a useful immunohistochemical marker for the identification of AA II and may be helpful for the neuropathological diagnosis of metabolic/hepatic encephalopathy in difficult or equivocal cases.

Real-world performance of plasma p-tau181 in a heterogeneous memory clinic cohort.

OBJECTIVE: In light of clinical trials and disease-modifying therapies, an early identification of patients at-risk of developing Alzheimer's disease (AD) is crucial. Blood-based biomarkers have shown promising results regarding the in vivo detection of the earliest neuropathological changes in AD. Herein, we investigated the ability of plasma p-tau181 to act as a prescreening marker for amyloid positivity in a heterogeneous memory clinic-based cohort. METHODS: In this retrospective cross-sectional study, we included a total of 115 patients along the clinical AD continuum (mild cognitive impairment [MCI] due to AD, n = 62, probable AD dementia, n = 53). Based on their biomarker status, they were stratified into an amyloid-positive (Aß+, n = 88) or amyloid-negative cohort (Aß-, n = 27). Plasma and CSF p-tau181 concentrations were quantified using an ultrasensitive single-molecule array (SIMOA©). Furthermore, age- and sex-adjusted receiver operating characteristic (ROC) curves were calculated and the area under the curve (AUC) of each model was compared using DeLong's test for correlated AUC curves. RESULTS: The median (interquartile range [IQR]) concentration of plasma p-tau181 was significantly higher in Aß+ patients (3.6 pg/mL [2.5-4.6]), compared with Aß- patients (1.7 pg/mL [1.2-1.9], p < 0.001). Regarding the distinction between Aß+ and Aß- patients and the prediction of amyloid positivity, a high diagnostic accuracy for plasma p-tau181 with an AUC of 0.89 (95% CI = 0.82-0.95) was calculated. Adding the risk factors, age and APOE4, to the model did not significantly improve its performance. INTERPRETATION: Our findings demonstrate that plasma p-tau181 could be a noninvasive and feasible prescreening marker for amyloid positivity in a heterogeneous clinical AD cohort and therefore help in identifying those who would benefit from more invasive assessment of amyloid pathology.

Tau fibrils evade autophagy by excessive p62 coating and TAX1BP1 exclusion.

The accumulation of protein aggregates is a hallmark of many diseases, including Alzheimer's disease. As a major pillar of the proteostasis network, autophagy mediates the degradation of protein aggregates. The autophagy cargo receptor p62 recognizes ubiquitin on proteins and cooperates with TAX1BP1 to recruit the autophagy machinery. Paradoxically, protein aggregates are not degraded in various diseases despite p62 association. Here, we reconstituted the recognition by the autophagy receptors of physiological and pathological Tau forms. Monomeric Tau recruits p62 and TAX1BP1 via the sequential actions of the chaperone and ubiquitylation machineries. In contrast, Tau fibrils from Alzheimer's disease brains are recognized by p62 but fail to recruit TAX1BP1. This failure is due to the masking of fibrils ubiquitin moieties by p62. Tau fibrils are resistant to deubiquitylation, and, thus, this nonproductive interaction of p62 with the fibrils is irreversible. Our results shed light on the mechanism underlying autophagy evasion by protein aggregates and their consequent accumulation in disease.

Frequent Alzheimer's disease neuropathological change in patients with glioblastoma.

Background: The incidence of brain cancer and neurodegenerative diseases is increasing with a demographic shift towards aging populations. Biological parallels have been observed between glioblastoma and Alzheimer's disease (AD), which converge on accelerated brain aging. Here, we aimed to map the cooccurrence of AD neuropathological change (ADNC) in the tumor-adjacent cortex of patients with glioblastoma. Methods: Immunohistochemical screening of AD markers amyloid beta (Abeta), amyloid precursor protein (APP), and hyperphosphorylated tau (pTau) was conducted in 420 tumor samples of 205 patients. For each cortex area, we quantified ADNC, neurons, tumor cells, and microglia. Results: Fifty-two percent of patients (N = 106/205) showed ADNC (Abeta and pTau, Abeta or pTau) in the tumor-adjacent cortex, with histological patterns widely consistent with AD. ADNC was positively correlated with patient age and varied spatially according to Thal phases and Braak stages. It decreased with increasing tumor cell infiltration (P < .0001) and was independent of frequent expression of APP in neuronal cell bodies (N = 182/205) and in tumor necrosis-related axonal spheroids (N = 195/205; P = .46). Microglia response was most present in tumor cell infiltration plus ADNC, being further modulated by patient age and sex. ADNC did not impact patient survival in the present cohort. Conclusions: Our findings highlight the frequent presence of ADNC in the glioblastoma vicinity, which was linked to patient age and tumor location. The cooccurrence of AD and glioblastoma seemed stochastic without clear spatial relation. ADNC did not impact patient survival in our cohort.

A navigated, robot-driven laser craniotomy tool for frameless depth electrode implantation. An in-vivo recovery animal study.

Objectives: We recently introduced a frameless, navigated, robot-driven laser tool for depth electrode implantation as an alternative to frame-based procedures. This method has only been used in cadaver and non-recovery studies. This is the first study to test the robot-driven laser tool in an in vivo recovery animal study. Methods: A preoperative computed tomography (CT) scan was conducted to plan trajectories in sheep specimens. Burr hole craniotomies were performed using a frameless, navigated, robot-driven laser tool. Depth electrodes were implanted after cut-through detection was confirmed. The electrodes were cut at the skin level postoperatively. Postoperative imaging was performed to verify accuracy. Histopathological analysis was performed on the bone, dura, and cortex samples. Results: Fourteen depth electrodes were implanted in two sheep specimens. Anesthetic protocols did not show any intraoperative irregularities. One sheep was euthanized on the same day of the procedure while the other sheep remained alive for 1 week without neurological deficits. Postoperative MRI and CT showed no intracerebral bleeding, infarction, or unintended damage. The average bone thickness was 6.2 mm (range 4.1-8.0 mm). The angulation of the planned trajectories varied from 65.5° to 87.4°. The deviation of the entry point performed by the frameless laser beam ranged from 0.27 mm to 2.24 mm. The histopathological analysis did not reveal any damage associated with the laser beam. Conclusion: The novel robot-driven laser craniotomy tool showed promising results in this first in vivo recovery study. These findings indicate that laser craniotomies can be performed safely and that cut-through detection is reliable.

Clinical heterogeneity within the ALS-FTD spectrum in a family with a homozygous optineurin mutation.

OBJECTIVE: Mutations in the gene encoding for optineurin (OPTN) have been reported in the context of different neurodegenerative diseases including the amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) spectrum. Based on single case reports, neuropathological data in OPTN mutation carriers have revealed transactive response DNA-binding protein 43 kDa (TDP-43) pathology, in addition to accumulations of tau and alpha-synuclein. Herein, we present two siblings from a consanguineous family with a homozygous frameshift mutation in the OPTN gene and different clinical presentations. METHODS: Both affected siblings underwent (i) clinical, (ii) neurophysiological, (iii) neuropsychological, (iv) radiological, and (v) laboratory examinations, and (vi) whole-exome sequencing (WES). Postmortem histopathological examination was conducted in the index patient, who deceased at the age of 41. RESULTS: The index patient developed rapidly progressing clinical features of upper and lower motor neuron dysfunction as well as apathy and cognitive deterioration at the age of 41. Autopsy revealed an ALS-FTLD pattern associated with prominent neuronal and oligodendroglial TDP-43 pathology, and an atypical limbic 4-repeat tau pathology reminiscent of argyrophilic grain disease. The brother of the index patient exhibited behavioral changes and mnestic deficits at the age of 38 and was diagnosed with behavioral FTD 5 years later, without any evidence of motor neuron dysfunction. WES revealed a homozygous frameshift mutation in the OPTN gene in both siblings (NM_001008212.2: c.1078_1079del; p.Lys360ValfsTer18). INTERPRETATION: OPTN mutations can be associated with extensive TDP-43 pathology and limbic-predominant tauopathy and present with a heterogeneous clinical phenotype within the ALS-FTD spectrum within the same family.

HLA dependency and possible clinical relevance of intrathecally synthesized anti-IgLON5 IgG4 in anti-IgLON5 disease.

Background: Anti-IgLON5 disease is a rare chronic autoimmune disorder characterized by IgLON5 autoantibodies predominantly of the IgG4 subclass. Distinct pathogenic effects were described for anti-IgLON5 IgG1 and IgG4, however, with uncertain clinical relevance. Methods: IgLON5-specific IgG1-4 levels were measured in 46 sera and 20 cerebrospinal fluid (CSF) samples from 13 HLA-subtyped anti-IgLON5 disease patients (six females, seven males) using flow cytometry. Intervals between two consecutive serum or CSF samplings (31 and 10 intervals, respectively) were categorized with regard to the immunomodulatory treatment active at the end of the interval, changes of anti-IgLON5 IgG1 and IgG4 levels, and disease severity. Intrathecal anti-IgLON5 IgG4 synthesis (IS) was assessed using a quantitative method. Results: The median age at onset was 66 years (range: 54-75), disease duration 10 years (range: 15-156 months), and follow-up 25 months (range: 0-83). IgLON5-specific IgG4 predominance was observed in 38 of 46 (83%) serum and 11 of 20 (55%) CSF samples. Anti-IgLON5 IgG4 levels prior clinical improvement in CSF but not serum were significantly lower than in those prior stable/progressive disease. Compared to IgLON5 IgG4 levels in serum, CSF levels in HLA-DRB1*10:01 carriers were significantly higher than in non-carriers. Indeed, IgLON5-specific IgG4 IS was demonstrated not only in four of five HLA-DRB1*10:01 carriers but also in one non-carrier. Immunotherapy was associated with decreased anti-IgGLON5 IgG serum levels. In CSF, lower anti-IgLON5 IgG was associated with immunosuppressive treatments used in combination, that is, corticosteroids and/or azathioprine plus intravenous immunoglobulins or rituximab. Conclusion: Our findings might indicate that CSF IgLON5-specific IgG4 is frequently produced intrathecally, especially in HLA-DRB1*10:01 carriers. Intrathecally produced IgG4 may be clinically relevant. While many immunotherapies reduce serum IgLON5 IgG levels, more intense immunotherapies induce clinical improvement and may be able to target intrathecally produced anti-IgLON5 IgG. Further studies need to confirm whether anti-IgLON5 IgG4 IS is a suitable prognostic and predictive biomarker in anti-IgLON5 disease.

Multifactorial White Matter Damage in the Acute Phase and Pre-Existing Conditions May Drive Cognitive Dysfunction after SARS-CoV-2 Infection: Neuropathology-Based Evidence.

BACKGROUND: There is an urgent need to better understand the mechanisms underlying acute and long-term neurological symptoms after COVID-19. Neuropathological studies can contribute to a better understanding of some of these mechanisms. METHODS: We conducted a detailed postmortem neuropathological analysis of 32 patients who died due to COVID-19 during 2020 and 2021 in Austria. RESULTS: All cases showed diffuse white matter damage with a diffuse microglial activation of a variable severity, including one case of hemorrhagic leukoencephalopathy. Some cases revealed mild inflammatory changes, including olfactory neuritis (25%), nodular brainstem encephalitis (31%), and cranial nerve neuritis (6%), which were similar to those observed in non-COVID-19 severely ill patients. One previously immunosuppressed patient developed acute herpes simplex encephalitis. Acute vascular pathologies (acute infarcts 22%, vascular thrombosis 12%, diffuse hypoxic-ischemic brain damage 40%) and pre-existing small vessel diseases (34%) were frequent findings. Moreover, silent neurodegenerative pathologies in elderly persons were common (AD neuropathologic changes 32%, age-related neuronal and glial tau pathologies 22%, Lewy bodies 9%, argyrophilic grain disease 12.5%, TDP43 pathology 6%). CONCLUSIONS: Our results support some previous neuropathological findings of apparently multifactorial and most likely indirect brain damage in the context of SARS-CoV-2 infection rather than virus-specific damage, and they are in line with the recent experimental data on SARS-CoV-2-related diffuse white matter damage, microglial activation, and cytokine release.