Identification of TARDBP Gly298Ser as a founder mutation for amyotrophic lateral sclerosis in Southern China

Understanding age-related pathologic changes in TDP-43 functions and the consequence on RNA splicing and signalling in health and disease

TAR DNA binding protein-43 (TDP-43) is a key component in RNA splicing which plays a crucial role in the aging process. In neurodegenerative diseases such as amyotrophic lateral sclerosis, frontotemporal dementia and limbic-predominant age-related TDP-43 encephalopathy, TDP-43 can be mutated, mislocalised out of the nucleus of neurons and glial cells and form cytoplasmic inclusions. These TDP-43 alterations can lead to its RNA splicing dysregulation and contribute to mis-splicing of various types of RNA, such as mRNA, microRNA, and circular RNA. These changes can result in the generation of an altered transcriptome and proteome within cells, ultimately changing the diversity and quantity of gene products. In this review, we summarise the findings of novel atypical RNAs resulting from TDP-43 dysfunction and their potential as biomarkers or targets for therapeutic development.

Disease survival and progression in TARDBP ALS patients from Sardinia, Italy

BACKGROUND

Common genes implicated in amyotrophic lateral sclerosis (ALS) development may also influence its progression rate. The C9orf72 mutations featured a faster progression rate while the European SOD1 mutations were associated with a slower progression. In this study, we assessed the relationship between TARDBP and ALS progression/survival.

METHODS

ALS incident patients (2010-2019) were diagnosed by El Escorial revised criteria and staged over the disease course by the King's staging system. Disease progression was analysed by Kaplan-Meier survival curves and Cox regression models, with survival measured from symptom onset to death/tracheostomy or censor date.

RESULTS

The study population included 76 patients carrying TARDBP mutations (A382T/G295S), 28 patients carrying the C9orf72 GGGGCC expansion, and 158 patients who had no evidence of causative genetic mutations (nmALS group). TARDBP patients reached death/tracheostomy later than C9orf72 and nmALS patients, independently of possible prognostic indicators (sex, age at ALS onset, diagnostic delay, phenotype at onset, and family history of ALS). On King's staging, the time elapsed between disease onset (King's stage 1) and involvement of the second body region (King's stage 2B) was similar in TARDBP and nmALS patients but longer in TARDBP than in C9orf72 patients. TARDBP patients reached King's stages 3 and 4 later than C9orf72 and nmALS patients.

CONCLUSIONS

TARDBP patients have a better survival/prognosis than C9orf72-positive and nmALS patients. King's staging also suggested that the higher survival rate and the slower progression associated with the TARDBP mutation could mainly be attributed to the longer time elapsed between King's stages 2B to 3.

Variability in Clinical Phenotype in TARDBP Mutations: Amyotrophic Lateral Sclerosis Case Description and Literature Review

Mutations in the 43 kDa transactive-response (TAR)-DNA-binding protein (TARDBP) are associated with 2-5% of familial Amyotrophic Lateral Sclerosis (ALS) cases. TAR DNA-Binding Protein 43 (TDP-43) is an RNA/DNA-binding protein involved in several cellular mechanisms (e.g., transcription, pre-mRNA processing, and splicing). Many ALS-linked TARDBP mutations have been described in the literature, but few phenotypic data on monogenic TARDBP-mutated ALS are available. In this paper, (1) we describe the clinical features of ALS patients carrying mutations in the TARDBP gene evaluated at the Tertiary ALS Center at Maggiore della Carità University Hospital, Novara, Italy, from 2010 to 2020 and (2) present the results of our review of the literature on this topic, analyzing data obtained for 267 patients and highlighting their main clinical and demographic features.

Novel CSF Biomarkers Tracking Autoimmune Inflammatory and Neurodegenerative Aspects of CNS Diseases

The accurate diagnosis of neuroinflammatory (NIDs) and neurodegenerative (NDDs) diseases and the stratification of patients into disease subgroups with distinct disease-related characteristics that reflect the underlying pathology represents an unmet clinical need that is of particular interest in the era of emerging disease-modifying therapies (DMT). Proper patient selection for clinical trials and identifying those in the prodromal stages of the diseases or those at high risk will pave the way for precision medicine approaches and halt neuroinflammation and/or neurodegeneration in early stages where this is possible. Towards this direction, novel cerebrospinal fluid (CSF) biomarker candidates were developed to reflect the diseased organ's pathology better. Μisfolded protein accumulation, microglial activation, synaptic dysfunction, and finally, neuronal death are some of the pathophysiological aspects captured by these biomarkers to support proper diagnosis and screening. We also describe advances in the field of molecular biomarkers, including miRNAs and extracellular nucleic acids known as cell-free DNA and mitochondrial DNA molecules. Here we review the most important of these novel CSF biomarkers of NIDs and NDDs, focusing on their involvement in disease development and emphasizing their ability to define homogeneous disease phenotypes and track potential treatment outcomes that can be mirrored in the CSF compartment.