Genetic defects of gamma-secretase genes in a multiple myeloma patient with high and dysregulated BCMA surface density: A case report

Multiple myeloma (MM) cells from 1 out of 20 patient expressed high basal levels of membrane B-cell maturation antigen (BCMA, TNFRSF17, CD269), which was not upregulated by gamma-secretase inhibitor, suggesting a defective BCMA shedding by gamma-secretase. Genetic analyses of the patient's bone marrow DNA showed no mutations within the BCMA coding region, but rather partial deletion of PSEN1 and amplification of PSEN2, which encode alternative catalytic units of gamma-secretase. Altogether the data suggest that pt#12 MM cells express high and dysregulated BCMA with no shedding, due to genetic alterations of one or more gamma-secretase subunits.

Harmonizing Genetic Testing for Parkinson's Disease: Results of the PARKNET Multicentric Study

BACKGROUND AND OBJECTIVE

Early-onset Parkinson's disease (EOPD) commonly recognizes a genetic basis; thus, patients with EOPD are often addressed to diagnostic testing based on next-generation sequencing (NGS) of PD-associated multigene panels. However, NGS interpretation can be challenging in a diagnostic setting, and few studies have addressed this issue so far.

METHODS

We retrospectively collected data from 648 patients with PD with age at onset younger than 55 years who underwent NGS of a minimal shared panel of 15 PD-related genes, as well as PD-multiplex ligation-dependent probe amplification in eight Italian diagnostic laboratories. Data included a minimal clinical dataset, the complete list of variants included in the diagnostic report, and final interpretation (positive/negative/inconclusive). Patients were further stratified based on age at onset ≤40 years (very EOPD, n = 157). All variants were reclassified according to the latest American College of Medical Genetics and Genomics criteria. For classification purposes, PD-associated GBA1 variants were considered diagnostic.

RESULTS

In 186 of 648 (29%) patients, the diagnostic report listed at least one variant, and the outcome was considered diagnostic (positive) in 105 (16%). After reanalysis, diagnosis changed in 18 of 186 (10%) patients, with 5 shifting from inconclusive to positive and 13 former positive being reclassified as inconclusive. A definite diagnosis was eventually reached in 97 (15%) patients, of whom the majority carried GBA1 variants or, less frequently, biallelic PRKN variants. In 89 (14%) cases, the genetic report was inconclusive.

CONCLUSIONS

This study attempts to harmonize reporting of PD genetic testing across several diagnostic labs and highlights current difficulties in interpreting genetic variants emerging from NGS-multigene panels, with relevant implications for counseling. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Phospholipase Family Enzymes in Lung Cancer: Looking for Novel Therapeutic Approaches

Lung cancer (LC) is the second most common neoplasm in men and the third most common in women. In the last decade, LC therapies have undergone significant improvements with the advent of immunotherapy. However, the effectiveness of the available treatments remains insufficient due to the presence of therapy-resistant cancer cells. For decades, chemotherapy and radiotherapy have dominated the treatment strategy for LC; however, relapses occur rapidly and result in poor survival. Malignant lung tumors are classified as either small- or non-small-cell lung carcinoma (SCLC and NSCLC). Despite improvements in the treatment of LC in recent decades, the benefits of surgery, radiotherapy, and chemotherapy are limited, although they have improved the prognosis of LC despite the persistent low survival rate due to distant metastasis in the late stage. The identification of novel prognostic molecular markers is crucial to understand the underlying mechanisms of LC initiation and progression. The potential role of phosphatidylinositol in tumor growth and the metastatic process has recently been suggested by some researchers. Phosphatidylinositols are lipid molecules and key players in the inositol signaling pathway that have a pivotal role in cell cycle regulation, proliferation, differentiation, membrane trafficking, and gene expression. In this review, we discuss the current understanding of phosphoinositide-specific phospholipase enzymes and their emerging roles in LC.

Genomic, transcriptomic and RNA editing analysis of human MM1 and VV2 sporadic Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is characterized by a broad phenotypic spectrum regarding symptoms, progression, and molecular features. Current sporadic CJD (sCJD) classification recognizes six main clinical-pathological phenotypes. This work investigates the molecular basis of the phenotypic heterogeneity of prion diseases through a multi-omics analysis of the two most common sCJD subtypes: MM1 and VV2. We performed DNA target sequencing on 118 genes on a cohort of 48 CJD patients and full exome RNA sequencing on post-mortem frontal cortex tissue on a subset of this cohort. DNA target sequencing identified multiple potential genetic contributors to the disease onset and phenotype, both in terms of coding, damaging-predicted variants, and enriched groups of SNPs in the whole cohort and the two subtypes. The results highlight a different functional impairment, with VV2 associated with higher impairment of the pathways related to dopamine secretion, regulation of calcium release and GABA signaling, showing some similarities with Parkinson's disease both on a genomic and a transcriptomic level. MM1 showed a gene expression profile with several traits shared with different neurodegenerative, without an apparent distinctive characteristic or similarities with a specific disease. In addition, integrating genomic and transcriptomic data led to the discovery of several sites of ADAR-mediated RNA editing events, confirming and expanding previous findings in animal models. On the transcriptomic level, this work represents the first application of RNA sequencing on CJD human brain samples. Here, a good clusterization of the transcriptomic profiles of the two subtypes was achieved, together with the finding of several differently impaired pathways between the two subtypes. The results add to the understanding of the molecular features associated with sporadic CJD and its most common subtypes, revealing strain-specific genetic signatures and functional similarities between VV2 and Parkinson's disease and providing preliminary evidence of RNA editing modifications in human sCJD.

Dementia-related genetic variants in an Italian population of early-onset Alzheimer’s disease

Early-onset Alzheimer’s disease (EOAD) is the most common form of early-onset dementia. Although three major genes have been identified as causative, the genetic contribution to the disease remains unsolved in many patients. Recent studies have identified pathogenic variants in genes representing a risk factor for developing Alzheimer’s disease (AD) and in causative genes for other degenerative dementias as responsible for EOAD. To study them further, we investigated a panel of candidate genes in 102 Italian EOAD patients, 45.10% of whom had a positive family history and 21.74% with a strong family history of dementia. We found that 10.78% of patients carried pathogenic or likely pathogenic variants, including a novel variant, in PSEN1, PSEN2, or APP, and 7.84% showed homozygosity for the ε4 APOE allele. Additionally, 7.84% of patients had a moderate risk allele in PSEN1, PSEN2, or TREM2 genes. Besides, we observed that 12.75% of our patients carried only a variant in genes associated with other neurodegenerative diseases. The combination of these variants contributes to explain 46% of cases with a definite familiarity and 32% of sporadic forms. Our results confirm the importance of extensive genetic screening in EOAD for clinical purposes, to select patients for future treatments and to contribute to the definition of overlapping pathogenic mechanisms between AD and other forms of dementia.

Extra Virgin Olive Oil (EVOO), a Mediterranean Diet Component, in the Management of Muscle Mass and Function Preservation

Aging results in a progressive decline in skeletal muscle mass, strength and function, a condition known as sarcopenia. This pathological condition is due to multifactorial processes including physical inactivity, inflammation, oxidative stress, hormonal changes, and nutritional intake. Physical therapy remains the standard approach to treat sarcopenia, although some interventions based on dietary supplementation are in clinical development. In this context, thanks to its known anti-inflammatory and antioxidative properties, there is great interest in using extra virgin olive oil (EVOO) supplementation to promote muscle mass and health in sarcopenic patients. To date, the molecular mechanisms responsible for the pathological changes associated with sarcopenia remain undefined; however, a complete understanding of the signaling pathways that regulate skeletal muscle protein synthesis and their behavior during sarcopenia appears vital for defining how EVOO might attenuate muscle wasting during aging. This review highlights the main molecular players that control skeletal muscle mass, with particular regard to sarcopenia, and discusses, based on the more recent findings, the potential of EVOO in delaying/preventing loss of muscle mass and function, with the aim of stimulating further research to assess dietary supplementation with EVOO as an approach to prevent or delay sarcopenia in aging individuals.

Identification of recurrent genetic patterns from targeted sequencing panels with advanced data science: a case-study on sporadic and genetic neurodegenerative diseases

Background

Targeted Next Generation Sequencing is a common and powerful approach used in both clinical and research settings. However, at present, a large fraction of the acquired genetic information is not used since pathogenicity cannot be assessed for most variants. Further complicating this scenario is the increasingly frequent description of a poli/oligogenic pattern of inheritance showing the contribution of multiple variants in increasing disease risk. We present an approach in which the entire genetic information provided by target sequencing is transformed into binary data on which we performed statistical, machine learning, and network analyses to extract all valuable information from the entire genetic profile. To test this approach and unbiasedly explore the presence of recurrent genetic patterns, we studied a cohort of 112 patients affected either by genetic Creutzfeldt–Jakob (CJD) disease caused by two mutations in the PRNP gene (p.E200K and p.V210I) with different penetrance or by sporadic Alzheimer disease (sAD).

Results

Unsupervised methods can identify functionally relevant sources of variation in the data, like haplogroups and polymorphisms that do not follow Hardy–Weinberg equilibrium, such as the NOTCH3 rs11670823 (c.3837 + 21 T > A). Supervised classifiers can recognize clinical phenotypes with high accuracy based on the mutational profile of patients. In addition, we found a similar alteration of allele frequencies compared the European population in sporadic patients and in V210I-CJD, a poorly penetrant PRNP mutation, and sAD, suggesting shared oligogenic patterns in different types of dementia. Pathway enrichment and protein–protein interaction network revealed different altered pathways between the two PRNP mutations.

Conclusions

We propose this workflow as a possible approach to gain deeper insights into the genetic information derived from target sequencing, to identify recurrent genetic patterns and improve the understanding of complex diseases. This work could also represent a possible starting point of a predictive tool for personalized medicine and advanced diagnostic applications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01173-4.

Three-Dimensional Virtual Anatomy as a New Approach for Medical Student's Learning

Most medical and health science schools adopt innovative tools to implement the teaching of anatomy to their undergraduate students. The increase in technological resources for educational purposes allows the use of virtual systems in the field of medicine, which can be considered decisive for improving anatomical knowledge, a requisite for safe and competent medical practice. Among these virtual tools, the Anatomage Table 7.0 represents, to date, a pivotal anatomical device for student education and training medical professionals. This review focuses attention on the potential of the Anatomage Table in the anatomical learning process and clinical practice by discussing these topics based on recent publication findings and describing their trends during the COVID-19 pandemic period. The reports documented a great interest in and a positive impact of the use of this technological table by medical students for teaching gross anatomy. Anatomage allows to describe, with accuracy and at high resolution, organ structure, vascularization, and innervation, as well as enables to familiarize with radiological images of real patients by improving knowledge in the radiological and surgical fields. Furthermore, its use can be considered strategic in a pandemic period, since it ensures, through an online platform, the continuation of anatomical and surgical training on dissecting cadavers.

Targeted sequencing panels in Italian ALS patients support different etiologies in the ALS/FTD continuum

BACKGROUND

5-10% of amyotrophic lateral sclerosis (ALS) patients presented a positive family history (fALS). More than 30 genes have been identified in association with ALS/frontotemporal dementia (FTD) spectrum, with four major genes accounting for 60-70% of fALS. In this paper, we aimed to assess the contribution to the pathogenesis of major and rare ALS/FTD genes in ALS patients.

METHODS

We analyzed ALS and ALS/FTD associated genes by direct sequencing or next-generation sequencing multigene panels in ALS patients.

RESULTS

Genetic abnormalities in ALS major genes included repeated expansions of hexanucleotide in C9orf72 gene (7.3%), mutations in SOD1 (4.9%), FUS (2.1%), and TARDBP (2.4%), whereas variants in rare ALS/FTD genes affected 15.5% of subjects overall, most frequently involving SQSTM1 (3.4%), and CHMP2B (1.9%). We found clustering of variants in ALS major genes in patients with a family history for "pure" ALS, while ALS/FTD related genes mainly occurred in patients with a family history for other neurodegenerative diseases (dementia and/or parkinsonism).

CONCLUSIONS

Our data support the presence of two different genetic components underlying ALS pathogenesis, related to the presence of a family history for ALS or other neurodegenerative diseases. Thus, family history may help in optimizing the genetic screening protocol to be applied.

Cell signaling pathways in autosomal-dominant leukodystrophy (ADLD): the intriguing role of the astrocytes

Autosomal-dominant leukodystrophy (ADLD) is a rare fatal neurodegenerative disorder with overexpression of the nuclear lamina component, Lamin B1 due to LMNB1 gene duplication or deletions upstream of the gene. The molecular mechanisms responsible for driving the onset and development of this pathology are not clear yet. Vacuolar demyelination seems to be one of the most significant histopathological observations of ADLD. Considering the role of oligodendrocytes, astrocytes, and leukemia inhibitory factor (LIF)-activated signaling pathways in the myelination processes, this work aims to analyze the specific alterations in different cell populations from patients with LMNB1 duplications and engineered cellular models overexpressing Lamin B1 protein. Our results point out, for the first time, that astrocytes may be pivotal in the evolution of the disease. Indeed, cells from ADLD patients and astrocytes overexpressing LMNB1 show severe ultrastructural nuclear alterations, not present in oligodendrocytes overexpressing LMNB1. Moreover, the accumulation of Lamin B1 in astrocytes induces a reduction in LIF and in LIF-Receptor (LIF-R) levels with a consequential decrease in LIF secretion. Therefore, in both our cellular models, Jak/Stat3 and PI3K/Akt axes, downstream of LIF/LIF-R, are downregulated. Significantly, the administration of exogenous LIF can partially reverse the toxic effects induced by Lamin B1 accumulation with differences between astrocytes and oligodendrocytes, highlighting that LMNB1 overexpression drastically affects astrocytic function reducing their fundamental support to oligodendrocytes in the myelination process. In addition, inflammation has also been investigated, showing an increased activation in ADLD patients' cells.

A geroscience approach for Parkinson's disease: Conceptual framework and design of PROPAG-AGEING project

Advanced age is the major risk factor for idiopathic Parkinson's disease (PD), but to date the biological relationship between PD and ageing remains elusive. Here we describe the rationale and the design of the H2020 funded project "PROPAG-AGEING", whose aim is to characterize the contribution of the ageing process to PD development. We summarize current evidences that support the existence of a continuum between ageing and PD and justify the use of a Geroscience approach to study PD. We focus in particular on the role of inflammaging, the chronic, low-grade inflammation characteristic of elderly physiology, which can propagate and transmit both locally and systemically. We then describe PROPAG-AGEING design, which is based on the multi-omic characterization of peripheral samples from clinically characterized drug-naïve and advanced PD, PD discordant twins, healthy controls and "super-controls", i.e. centenarians, who never showed clinical signs of motor disability, and their offspring. Omic results are then validated in a large number of samples, including in vitro models of dopaminergic neurons and healthy siblings of PD patients, who are at higher risk of developing PD, with the final aim of identifying the molecular perturbations that can deviate the trajectories of healthy ageing towards PD development.

Comparison between plasma and cerebrospinal fluid biomarkers for the early diagnosis and association with survival in prion disease

OBJECTIVE

To compare the diagnostic accuracy and the prognostic value of blood and cerebrospinal fluid (CSF) tests across prion disease subtypes.

METHODS

We used a single-molecule immunoassay to measure tau and neurofilament light chain (NfL) protein levels in the plasma and assessed CSF total(t)-tau, NfL and protein 14-3-3 levels in patients with prion disease (n=336), non-prion rapidly progressive dementias (n=106) and non-neurodegenerative controls (n=37). We then evaluated each plasma and CSF marker for diagnosis and their association with survival, taking into account the disease subtype, which is a strong independent prognostic factor in prion disease.

RESULTS

Plasma tau and NfL concentrations were higher in patients with prion disease than in non-neurodegenerative controls and non-prion rapidly progressive dementias. Plasma tau showed higher diagnostic value than plasma NfL, but a lower accuracy than the CSF proteins t-tau and 14-3-3. In the whole prion cohort, both plasma (tau and NfL) and CSF (t-tau, 14-3-3 and NfL) markers were significantly associated with survival and showed similar prognostic values. However, the intrasubtype analysis revealed that only CSF t-tau in sporadic Creutzfeldt-Jakob disease (sCJD) MM(V)1, plasma tau and CSF t-tau in sCJD VV2, and plasma NfL in slowly progressive prion diseases were significantly associated with survival after accounting for covariates.

CONCLUSIONS

Plasma markers have lower diagnostic accuracy than CSF biomarkers. Plasma tau and NfL and CSF t-tau are significantly associated with survival in prion disease in a subtype-specific manner and can be used to improve clinical trial stratification and clinical care.

Identification of novel risk loci and causal insights for sporadic Creutzfeldt-Jakob disease: a genome-wide association study

BACKGROUND

Human prion diseases are rare and usually rapidly fatal neurodegenerative disorders, the most common being sporadic Creutzfeldt-Jakob disease (sCJD). Variants in the PRNP gene that encodes prion protein are strong risk factors for sCJD but, although the condition has similar heritability to other neurodegenerative disorders, no other genetic risk loci have been confirmed. We aimed to discover new genetic risk factors for sCJD, and their causal mechanisms.

METHODS

We did a genome-wide association study of sCJD in European ancestry populations (patients diagnosed with probable or definite sCJD identified at national CJD referral centres) with a two-stage study design using genotyping arrays and exome sequencing. Conditional, transcriptional, and histological analyses of implicated genes and proteins in brain tissues, and tests of the effects of risk variants on clinical phenotypes, were done using deep longitudinal clinical cohort data. Control data from healthy individuals were obtained from publicly available datasets matched for country.

FINDINGS

Samples from 5208 cases were obtained between 1990 and 2014. We found 41 genome-wide significant single nucleotide polymorphisms (SNPs) and independently replicated findings at three loci associated with sCJD risk; within PRNP (rs1799990; additive model odds ratio [OR] 1·23 [95% CI 1·17-1·30], p=2·68 × 10^-15; heterozygous model p=1·01 × 10^-135), STX6 (rs3747957; OR 1·16 [1·10-1·22], p=9·74 × 10^-9), and GAL3ST1 (rs2267161; OR 1·18 [1·12-1·25], p=8·60 × 10^-10). Follow-up analyses showed that associations at PRNP and GAL3ST1 are likely to be caused by common variants that alter the protein sequence, whereas risk variants in STX6 are associated with increased expression of the major transcripts in disease-relevant brain regions.

INTERPRETATION

We present, to our knowledge, the first evidence of statistically robust genetic associations in sporadic human prion disease that implicate intracellular trafficking and sphingolipid metabolism as molecular causal mechanisms. Risk SNPs in STX6 are shared with progressive supranuclear palsy, a neurodegenerative disease associated with misfolding of protein tau, indicating that sCJD might share the same causal mechanisms as prion-like disorders.

FUNDING

Medical Research Council and the UK National Institute of Health Research in part through the Biomedical Research Centre at University College London Hospitals National Health Service Foundation Trust.

A Novel Eight Octapeptide Repeat Insertion in PRNP Causing Prion Disease in a Danish Family

Octapeptide repeat insertions (OPRI) found in the prion protein gene (PRNP) constitute a subgroup of pathogenic mutations linked to inherited prion diseases, a hallmark of which is a misfolded prion protein. The number of repeats in OPRI has been associated with different disease phenotypes. However, due to the rarity of the cases and heterogenous disease manifestations, the recognition and classification of these variants has been difficult. Here, we report the first Danish family, the fifth worldwide, carrying a novel 8-OPRI with a unique sequence of the additional 8 inserts: R1-R2-R2-R3-R2-R2-R2a-R2-R3g-R2-R2-R3-R4. The mutation was found on the allele coding for methionine at codon 129 in the PRNP gene. The clinical exome sequencing revealed that no other dementia-associated genes harbored pathogenic alterations. Mutation carriers had onset of symptoms in their early thirties, but disease duration varied from 5 to 11 years. Progressive dementia with psychiatric and motor symptoms were the most prominent clinical features. Clinical, pathological, and genetic characteristics of other 4 reported families with 8-OPRI were reviewed and compared with the findings in the Danish family.

Molecular Characterization of the Danish Prion Diseases Cohort With Special Emphasis on Rare and Unique Cases

The purpose of this study was to perform an updated reclassification of all definite prion disease cases with available fresh-frozen samples referred to the Danish Reference Center over the past 40 years, putting a special emphasis on the molecular characterization of novel disease subtypes. Investigation of the Danish prion diseases cohort revealed rare sporadic Creutzfeldt-Jakob disease cases with mixed subtypes and subtypes with previously uncharacterized white matter plaques, a new case of sporadic fatal insomnia, and 3 novel mutations, including 2 large octapeptide repeat insertions, and a point mutation in the prion protein gene. The evaluation of methionine and valine distribution at codon 129 among the prion disease patients in the cohort revealed the increased prevalence of methionine homozygotes compared to the general population. This observation was in line with the prevalence reported in other Caucasian prion disease cohort studies. Reclassification of the old prion diseases cohort revealed unique cases, the molecular characterization of which improves prion diseases classification, diagnostic accuracy, genetic counseling of affected families, and the understanding of disease biology.

First case of an UBQLN2 gene mutation causing frontotemporal dementia preceded by adult onset psychiatric symptoms

Recently, mutations in genes related to frontotemporal dementia and/or amyotrophic lateral sclerosis have been described as the cause of late onset psychosis. Here, we report a 68-year-old patient, carrier of a mutation in the gene encoding ubiquilin-2 (UBQLN2), who presented adult onset psychotic manifestations followed by a dysexecutive syndrome compatible with the diagnosis of behavioral variant of frontotemporal dementia. Therefore, we suggest that variants in UBQLN2 should be sought in patients with this clinical condition preceded by psychiatric disorders.

CSF biomarkers of neuroinflammation in distinct forms and subtypes of neurodegenerative dementia

BACKGROUND

In neurodegenerative dementias (NDs) such as prion disease, Alzheimer's disease (AD), and frontotemporal lobar degeneration (FTLD), protein misfolding leads to the tissue deposition of protein aggregates which, in turn, trigger neuroinflammation and neurodegeneration. Cerebrospinal fluid (CSF) biomarkers have the potential to reflect different aspects of these phenomena across distinct clinicopathological subtypes and disease stages.

METHODS

We investigated CSF glial markers, namely chitotriosidase 1 (CHIT1), chitinase-3-like protein 1 (YKL-40) and glial fibrillary acidic protein (GFAP) in prion disease subtypes (n = 101), AD (n = 40), clinicopathological subgroups of FTLD (n = 72), and controls (n = 40) using validated, commercially available ELISA assays. We explored glial biomarker levels' associations with disease variables and neurodegenerative CSF biomarkers and evaluated their diagnostic accuracy. The genotype of the CHIT1 rs3831317 polymorphic site was also analyzed.

RESULTS

Each ND group showed increased levels of CHIT1, YKL-40, and GFAP compared to controls with a difference between prion disease and AD or FTLD limited to YKL-40, which showed higher values in the former group. CHIT1 levels were reduced in both heterozygotes and homozygotes for the CHIT1 24-bp duplication (rs3831317) in FTLD and controls, but this effect was less significant in AD and prion disease. After stratification according to molecular subgroups, we demonstrated (i) an upregulation of all glial markers in Creutzfeldt-Jakob disease VV2 compared to other disease subtypes, (ii) a difference in CHIT1 levels between FTLD with TAU and TDP43 pathology, and (iii) a marked increase of YKL-40 in FTLD with amyotrophic lateral sclerosis (ALS) in comparison with FTLD without ALS. In prion disease, glial markers correlated with disease stage and were already elevated in one pre-symptomatic case of Gerstmann-Sträussler-Scheinker disease. Regarding the diagnostic value, YKL-40 was the only glial marker that showed a moderate accuracy in the distinction between controls and NDs.

CONCLUSIONS

NDs share a CSF profile characterized by increased levels of CSF CHIT1, YKL-40, and GFAP, which likely reflects a common neuroinflammatory response to protein misfolding and aggregation. CSF glial markers of neuroinflammation demonstrate limited diagnostic value but have some potential for monitoring the clinical and, possibly, preclinical phases of NDs.

Cerebrospinal Fluid Biomarkers in Patients with Frontotemporal Dementia Spectrum: A Single-Center Study

Cerebrospinal fluid (CSF) neurofilament light chain protein (NfL) and Alzheimer's disease (AD) core biomarker levels have been evaluated in cohorts of patients with frontotemporal dementia spectrum (FTD), but the distribution of values across the different clinical syndromes and underlying proteinopathies, and the relative diagnostic accuracy appear discordant among studies. We measured CSF NfL, total (t)-tau, phosphorylated (p)-tau, and amyloid-β (Aβ)42 in healthy controls (n = 38) and subjects with a clinical, genetic, CSF biomarker-based, and/or neuropathological diagnosis of FTD (n = 141) or AD (n = 60). Sub-analyses were conducted in a proportion of subjects with definite and/or probable frontotemporal lobar degeneration with tau (FTLD-TAU) (n = 42) or TDP43 pathology (FTLD-TDP) (n = 36). Both FTD and AD groups showed significantly increased CSF NfL levels in comparison to controls (p < 0.001). CSF NfL levels were significantly higher in FTD patients than in AD (p < 0.001), reaching the highest values in amyotrophic lateral sclerosis associated with FTD. Patients with probable and definite FTLD-TDP had significantly higher NfL levels (p < 0.001) and lower p-tau/t-tau values (p < 0.001) in comparison with probable and definite FTLD-TAU cases. NfL showed good diagnostic accuracy in the distinction between FTD and controls (AUC 0.862±0.027) and yielded an accuracy (AUC 0.861±0.045) comparable to that of the p-tau/t-tau ratio (AUC 0.814±0.050), with 80.0% sensitivity and 81.0% specificity, in the discrimination between probable/definite FTLD-TAU and FTLD-TDP. Our data further validate CSF NfL as a surrogate biomarker of neurodegeneration and disease severity in patients with FTD spectrum. Moreover, they demonstrate a good diagnostic value for NfL and p-tau/t-tau ratio in the discrimination between FTLD-TAU and FTLD-TDP.

The characterization of AD/PART co-pathology in CJD suggests independent pathogenic mechanisms and no cross-seeding between misfolded Aβ and prion proteins

Current evidence indicating a role of the human prion protein (PrP) in amyloid-beta (Aβ) formation or a synergistic effect between Aβ and prion pathology remains controversial. Conflicting results also concern the frequency of the association between the two protein misfolding disorders and the issue of whether the apolipoprotein E gene (APOE) and the prion protein gene (PRNP), the major modifiers of Aβ- and PrP-related pathologies, also have a pathogenic role in other proteinopathies, including tau neurofibrillary degeneration. Here, we thoroughly characterized the Alzheimer’s disease/primary age-related tauopathy (AD/PART) spectrum in a series of 450 cases with definite sporadic or genetic Creutzfeldt-Jakob disease (CJD). Moreover, we analyzed: (i) the effect of variables known to affect CJD pathogenesis and the co-occurring Aβ- and tau-related pathologies; (II) the influence of APOE genotype on CJD pathology, and (III) the effect of AD/PART co-pathology on the clinical CJD phenotype. AD/PART characterized 74% of CJD brains, with 53.3% and 8.2% showing low or intermediate-high levels of AD pathology, and 12.4 and 11.8% definite or possible PART. There was no significant correlation between variables affecting CJD (i.e., disease subtype, prion strain, PRNP genotype) and those defining the AD/PART spectrum (i.e., ABC score, Thal phase, prevalence of CAA and Braak stage), and no difference in the distribution of APOE ε4 and ε2 genotypes among CJD subtypes. Moreover, AD/PART co-pathology did not significantly affect the clinical presentation of typical CJD, except for a tendency to increase the frequency of cognitive symptoms. Altogether, the present results seem to exclude an increased prevalence AD/PART co-pathology in sporadic and genetic CJD, and indicate that largely independent pathogenic mechanisms drive AD/PART and CJD pathology even when they coexist in the same brain.

The First Historically Reported Italian Family with FTD/ALS Teaches a Lesson on C9orf72 RE: Clinical Heterogeneity and Oligogenic Inheritance

BACKGROUND

In 1969, Dazzi and Finizio reported the second observation of frontotemporal dementia (FTD) - amyotrophic lateral sclerosis (ALS) association in a large Italian kindred affected by an autosomal dominant form of ALS with high penetrance, frequent bulbar onset, and frequent cognitive decline.

OBJECTIVE

To expand the original characterization of this family and report the link with the C9orf72 repeat expansion (RE).

METHODS

We followed or reviewed the medical records of thirteen patients belonging to the original family and performed genetic analyses in four individuals.

RESULTS

Eight patients presented with ALS, four with FTD, and one with schizophrenia. The C9orf72 RE was found in three patients but not in the healthy survivor. Additionally, we found a novel possible pathogenic variant in the ITM2B gene in one patient with a complex phenotype, associating movement disorders, psychiatric and cognitive features, deafness, and optic atrophy. The neuropathological examination of this patient did not show the classical features of ITM2B mutation related dementias suggesting that the putative pathogenic mechanism does not involve cellular mislocalization of the protein or the formation of amyloid plaques.

CONCLUSION

We showed that the original Italian pedigree described with FTD/ALS carries the C9orf72 RE. Moreover, the finding of an additional mutation in another dementia causing gene in a patient with a more complex phenotype suggests a possible role of genetic modifiers in the disease. Together with other reports showing the coexistence of mutations in multiple ALS/FTD causative genes in the same family, our study supports an oligogenic etiology of ALS/FTD.

Antemortem CSF Aβ42/Aβ40 ratio predicts Alzheimer's disease pathology better than Aβ42 in rapidly progressive dementias

Objective

Despite the critical importance of pathologically confirmed samples for biomarker validation, only a few studies have correlated CSF Aβ42 values in vivo with postmortem Alzheimer's disease (AD) pathology, while none evaluated the CSF Aβ42/Aβ40 ratio. We compared CSF Aβ42 and Aβ42/Aβ40 ratio as biomarkers predicting AD neuropathological changes in patients with a short interval between lumbar puncture and death.

Methods

We measured CSF Aβ40 and Aβ42 and assessed AD pathology in 211 subjects with rapidly progressive dementia (RPD) and a definite postmortem diagnosis of Creutzfeldt-Jakob disease (n = 159), AD (n = 12), dementia with Lewy bodies (DLB, n = 4), AD/DLB mixed pathologies (n = 5), and various other pathologies (n = 31).

Results

The score reflecting the severity of Aβ pathology showed a better correlation with ln(Aβ42/Aβ40) (R ² = 0.506, β = -0.713, P < 0.001) than with ln(Aβ42) (R ² = 0.206, β = -0.458, P < 0.001), which was confirmed after adjusting for covariates. Aβ42/Aβ40 ratio showed significantly higher accuracy than Aβ42 in the distinction between cases with or without AD pathology (AUC 0.818 ± 0.028 vs. 0.643 ± 0.039), especially in patients with Aβ42 levels ≤495 pg/mL (AUC 0.888 ± 0.032 vs. 0.518 ± 0.064). Using a cut-off value of 0.810, the analysis of Aβ42/Aβ40 ratio yielded 87.0% sensitivity, 88.2% specificity in the distinction between cases with an intermediate-high level of AD pathology and those with low level or no AD pathology.

Interpretation

The present data support the use of CSF Aβ42/Aβ40 ratio as a biomarker of AD pathophysiology and noninvasive screener for Aβ pathology burden, and its introduction in the research diagnostic criteria for AD.

Age at onset of genetic (E200K) and sporadic Creutzfeldt-Jakob diseases is modulated by the CYP4X1 gene

OBJECTIVES

The Glu to Lys change at codon 200 (E200K) of the PRNP gene is the most frequent mutation associated to genetic Creutzfeldt-Jakob disease (CJD) and the only one responsible for geographical clusters. Patients carrying this mutation develop disease at different ages and show variable clinical phenotypes that are not affected by the methione/valine polymorphism at codon 129 of the PRNP gene suggesting the influence of other factors. The objective of this study is to look for genes other than PRNP that might be responsible of this variability.

METHODS

We searched for other genes by performing genome-wide analyses (GWA) on 19 patients with genetic CJD and 18 healthy subjects carrying the E200K mutation of PRNP and belonging to the Calabrian cluster in Italy. We then validate this result in 32 patients with E200K CJD from non-cluster areas and 259 patients with sporadic CJD referred to the Italian CJD national registry.

RESULTS AND CONCLUSIONS

We identified two single nucleotide polymorphisms on the CYP4X1 gene locus as candidate disease modifiers in patients with E200K CJD of the cluster area and confirmed this finding in 32 patients with E200K CJD from non-cluster areas and 259 patients with sporadic CJD. Our results indicate that the CYP4X1 gene modulates the onset of disease in patients with E200K genetic and sporadic CJD. This finding improves our understanding on the pathogenesis of CJD, suggests new targets for developing novel therapeutic strategies and might be useful for the stratification of patients in future preventive treatment trials.

Analysis of RNA Expression Profiles Identifies Dysregulated Vesicle Trafficking Pathways in Creutzfeldt-Jakob Disease

Functional genomics applied to the study of RNA expression profiles identified several abnormal molecular processes in experimental prion disease. However, only a few similar studies have been carried out to date in a naturally occurring human prion disease. To better characterize the transcriptional cascades associated with sporadic Creutzfeldt-Jakob disease (sCJD), the most common human prion disease, we investigated the global gene expression profile in samples from the frontal cortex of 10 patients with sCJD and 10 non-neurological controls by microarray analysis. The comparison identified 333 highly differentially expressed genes (hDEGs) in sCJD. Functional enrichment Gene Ontology analysis revealed that hDEGs were mainly associated with synaptic transmission, including GABA (q value = 0.049) and glutamate (q value = 0.005) signaling, and the immune/inflammatory response. Furthermore, the analysis of cellular components performed on hDEGs showed a compromised regulation of vesicle-mediated transport with mainly up-regulated genes related to the endosome (q value = 0.01), lysosome (q value = 0.04), and extracellular exosome (q value < 0.01). A targeted analysis of the retromer core component VPS35 (vacuolar protein sorting-associated protein 35) showed a down-regulation of gene expression (p value= 0.006) and reduced brain protein levels (p value= 0.002). Taken together, these results confirm and expand previous microarray expression profile data in sCJD. Most significantly, they also demonstrate the involvement of the endosomal-lysosomal system. Since the latter is a common pathogenic pathway linking together diseases, such as Alzheimer's and Parkinson's, it might be the focus of future studies aimed to identify new therapeutic targets in neurodegenerative diseases.

Two novel PRNP truncating mutations broaden the spectrum of prion amyloidosis

Truncating mutations in PRNP have been associated with heterogeneous phenotypes ranging from chronic diarrhea and neuropathy to dementia, either rapidly or slowly progressive. We identified novel PRNP stop‐codon mutations (p.Y163X, p.Y169X) in two Italian kindreds. Disease typically presented in the third or fourth decade with progressive autonomic failure and diarrhea. Moreover, one proband (p.Y163X) developed late cognitive decline, whereas some of his relatives presented with isolated cognitive and psychiatric symptoms. Our results strengthen the link between PRNP truncating mutations and systemic abnormal PrP deposition and support a wider application of PRNP screening to include unsolved cases of familial autonomic neuropathy.

Multiple variants in families with amyotrophic lateral sclerosis and frontotemporal dementia related to C9orf72 repeat expansion: further observations on their oligogenic nature

The C9orf72 repeat expansion (RE) is one of the most frequent causative mutations of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, it is still unclear how the C9orf72 RE can lead to a heterogeneous phenotype. Several reports have shown the coexistence of mutations in multiple ALS/FTD causative genes in the same family, suggesting an oligogenic etiology for ALS and FTD. Our aim was to investigate this phenomenon in an Italian group of ALS/FTD pedigrees carrying the C9orf72 RE. We included 11 subjects from 11 pedigrees with ALS/FTD and the C9orf72 RE. Mutation screening of FUS, SOD1 and TARDBP genes was performed by direct sequencing. A dementia-specific custom-designed targeted next-generation sequencing panel was used for screening dementia-associated genes mutations. We found genetic variants in additional ALS or dementia-related genes in four pedigrees, including the p.V47A variant in the TYROBP gene. As a group, double mutation carriers displayed a tendency toward a younger age at onset and a higher frequency of positive familiar history and of parkinsonism. Our observation supports the hypothesis that the co-presence of mutations in different genes may be relevant for the clinical expression of ALS/FTD and of their oligogenic nature.

A patient with PMP22-related hereditary neuropathy and DBH-gene-related dysautonomia

Recurrent focal neuropathy with liability to pressure palsies is a relatively frequent autosomal-dominant demyelinating neuropathy linked to peripheral myelin protein 22 (PMP22) gene deletions. The combination of PMP22 gene mutations with other genetic variants is known to cause a more severe phenotype than expected. We present the case of a patient with severe orthostatic hypotension since 12 years of age, who inherited a PMP22 gene deletion from his father. Genetic double trouble was suspected because of selective sympathetic autonomic disturbances. Through exome-sequencing analysis, we identified two novel mutations in the dopamine beta hydroxylase gene. Moreover, with interactome analysis, we excluded a further influence on the origin of the disease by variants in other genes. This case increases the number of unique patients presenting with dopamine-β-hydroxylase deficiency and of cases with genetically proven double trouble. Finding the right, complete diagnosis is crucial to obtain adequate medical care and appropriate genetic counseling.

Messenger RNA processing is altered in autosomal dominant leukodystrophy

Adult-onset autosomal dominant leukodystrophy (ADLD) is a slowly progressive neurological disorder characterized by autonomic dysfunction, followed by cerebellar and pyramidal features. ADLD is caused by duplication of the lamin B1 gene (LMNB1), which leads to its increased expression. The molecular pathways involved in the disease are still poorly understood. Hence, we analyzed global gene expression in fibroblasts and whole blood of LMNB1 duplication carriers and used Gene Set Enrichment Analysis to explore their gene signatures. We found that LMNB1 duplication is associated with dysregulation of genes involved in the immune system, neuronal and skeletal development. Genes with an altered transcriptional profile clustered in specific genomic regions. Among the dysregulated genes, we further studied the role of RAVER2, which we found to be overexpressed at mRNA and protein level. RAVER2 encodes a putative trans regulator of the splicing repressor polypyrimidine tract binding protein (PTB) and is likely implicated in alternative splicing regulation. Functional studies demonstrated an abnormal splicing pattern of several PTB-target genes and of the myelin protein gene PLP1, previously demonstrated to be involved in ADLD. Mutant mice with different lamin B1 expression levels confirmed that Raver2 expression is dependent on lamin B1 in neural tissue and determines an altered splicing pattern of PTB-target genes and Plp1. Overall our results demonstrate that deregulation of lamin B1 expression induces modified splicing of several genes, likely driven by raver-2 overexpression, and suggest that an alteration of mRNA processing could be a pathogenic mechanism in ADLD.

A mutation in PAK3 with a dual molecular effect deregulates the RAS/MAPK pathway and drives an X-linked syndromic phenotype

Loss-of-function mutations in PAK3 contribute to non-syndromic X-linked intellectual disability (NS-XLID) by affecting dendritic spine density and morphology. Linkage analysis in a three-generation family with affected males showing ID, agenesis of corpus callosum, cerebellar hypoplasia, microcephaly and ichthyosis, revealed a candidate disease locus in Xq21.33q24 encompassing over 280 genes. Subsequent to sequencing all coding exons of the X chromosome, we identified a single novel variant within the linkage region, affecting a conserved codon of PAK3. Biochemical studies showed that, similar to previous NS-XLID-associated lesions, the predicted amino acid substitution (Lys389Asn) abolished the kinase activity of PAK3. In addition, the introduced residue conferred a dominant-negative function to the protein that drives the syndromic phenotype. Using a combination of in vitro and in vivo studies in zebrafish embryos, we show that PAK3(N389) escapes its physiologic degradation and is able to perturb MAPK signaling via an uncontrolled kinase-independent function, which in turn leads to alterations of cerebral and craniofacial structures in vivo. Our data expand the spectrum of phenotypes associated with PAK3 mutations, characterize a novel mechanism resulting in a dual molecular effect of the same mutation with a complex PAK3 functional deregulation and provide evidence for a direct functional impact of aberrant PAK3 function on MAPK signaling.

The genetic and metabolic signature of oncocytic transformation implicates HIF1alpha destabilization

We previously showed that disruptive complex I mutations in mitochondrial DNA are the main genetic hallmark of oncocytic tumors of the thyroid and kidney. We here report a high frequency of homoplasmic disruptive mutations in a large panel of oncocytic pituitary and head-and-neck tumors. The presence of such mutations implicates disassembly of respiratory complex I in vivo which in turn contributes to the inability of oncocytic tumors to stabilize HIF1alpha and to display pseudo-hypoxia. By utilizing transmitochondrial cytoplasmic hybrids (cybrids), we induced the shift to homoplasmy of a truncating mutation in the mitochondria-coded MTND1 gene. Such shift is associated with a profound metabolic impairment leading to the imbalance of alpha-ketoglutarate and succinate, the Krebs cycle metabolites which are the main responsible for HIF1alpha stabilization. We conclude that the main hallmarks of oncocytic transformation, namely the occurrence of homoplasmic disruptive mutations and complex I disassembly, may explain the benign nature of oncocytic neoplasms through lack of HIF1alpha stabilization.