Identifying unstable CNG repeat loci in the human genome: a heuristic approach and implications for neurological disorders.

Tandem nucleotide repeat (TNR) expansions, particularly the CNG nucleotide configuration, are associated with a variety of neurodegenerative disorders. In this study, we aimed to identify novel unstable CNG repeat loci associated with the neurogenetic disorder spinocerebellar ataxia (SCA). Using a computational approach, 15,069 CNG repeat loci in the coding and noncoding regions of the human genome were identified. Based on the feature selection criteria (repeat length >10 and functional location of repeats), we selected 52 repeats for further analysis and evaluated the repeat length variability in 100 control subjects. A subset of 19 CNG loci observed to be highly variable in control subjects was selected for subsequent analysis in 100 individuals with SCA. The genes with these highly variable repeats also exhibited higher gene expression levels in the brain according to the tissue expression dataset (GTEx). No pathogenic expansion events were identified in patient samples, which is a limitation given the size of the patient group examined; however, these loci contain potential risk alleles for expandability. Recent studies have implicated GLS, RAI1, GIPC1, MED15, EP400, MEF2A, and CNKSR2 in neurological diseases, with GLS, GIPC1, MED15, RAI1, and MEF2A sharing the same repeat loci reported in this study. This finding validates the approach of evaluating repeat loci in different populations and their possible implications for human pathologies.

Molecular clues unveiling spinocerebellar ataxia type-12 pathogenesis.

Spinocerebellar Ataxia type-12 (SCA12) is a neurodegenerative disease caused by tandem CAG repeat expansion in the 5'-UTR/non-coding region of PPP2R2B. Molecular pathology of SCA12 has not been studied in the context of CAG repeats, and no appropriate models exist. We found in human SCA12-iPSC-derived neuronal lineage that expanded CAG in PPP2R2B transcript forms nuclear RNA foci and were found to sequester variety of proteins. Further, the ectopic expression of transcript containing varying length of CAG repeats exhibits non-canonical repeat-associated non-AUG (RAN) translation in multiple frames in HEK293T cells, which was further validated in patient-derived neural stem cells using specific antibodies. mRNA sequencing of the SCA12 and control neurons have shown a network of crucial transcription factors affecting neural fate, in addition to alteration of various signaling pathways involved in neurodevelopment. Altogether, this study identifies the molecular signatures of SCA12 disorder using patient-derived neuronal cell lines.

STRIDE-DB: a comprehensive database for exploration of instability and phenotypic relevance of short tandem repeats in the human genome.

Short Tandem Repeats (STRs) are genetic markers made up of repeating DNA sequences. The variations of the STRs are widely studied in forensic analysis, population studies and genetic testing for a variety of neuromuscular disorders. Understanding polymorphic STR variation and its cause is crucial for deciphering genetic information and finding links to various disorders. In this paper, we present STRIDE-DB, a novel and unique platform to explore STR Instability and its Phenotypic Relevance, and a comprehensive database of STRs in the human genome. We utilized RepeatMasker to identify all the STRs in the human genome (hg19) and combined it with frequency data from the 1000 Genomes Project. STRIDE-DB, a user-friendly resource, plays a pivotal role in investigating the relationship between STR variation, instability and phenotype. By harnessing data from genome-wide association studies (GWAS), ClinVar database, Alu loci, Haploblocks in genome and Conservation of the STRs, it serves as an important tool for researchers exploring the variability of STRs in the human genome and its direct impact on phenotypes. STRIDE-DB has its broad applicability and significance in various research domains like forensic sciences and other repeat expansion disorders. Database URL: https://stridedb.igib.res.in.

Generation and characterization of iPSC lines from Friedreich's ataxia patient (FRDA) with GAA.TTC repeat expansion in the Frataxin (FXN) gene's first intron (IGIBi016-A) and a non-FRDA healthy control individual (IGIBi017-A).

Friedreich's ataxia is a spinocerebellar degenerative disease caused by microsatellite (GAA.TTC)n repeat expansion in the first intron of FXN gene. Here, we developed iPSC lines from an FRDA patient (IGIBi016-A) and non-FRDA healthy control (IGIBi017-A). Both iPSC lines displayed typical iPSC morphology, expression of pluripotency markers, regular karyotypes (46, XY; 46, XX), capacity to grow into three germ layers, and FRDA hallmark -GAA repeat expansion and decreased FXN mRNA. Through these iPSC lines, FRDA phenotypes may be replicated in the in vitro assays, by creating neuron subtypes, cardiomyocytes and 3D organoids, for molecular and cellular biomarkers and therapeutic applications.

Genetic and in silico analysis of Indian sporadic young onset patient with amyotrophic lateral sclerosis.

Background: Amyotrophic lateral sclerosis (ALS) is an old onset devastating neurodegenerative disorder. Young-onset ALS cases especially sporadic ones who are between 25 and 45 years are rarely affected by the disease. Despite the identification of numerous candidate genes associated with ALS, the etiology of the disease remains elusive due to extreme genetic and phenotypic variability. The advent of affordable whole exome sequencing (WES) has opened new avenues for unraveling the disease's pathophysiology better. Methods and results: We aimed to determine the genetic basis of an Indian-origin, young onset sporadic ALS patient with very rapid deterioration of the disease course without any cognitive decline who was screened for mutations in major ALS candidate genes by WES. Variants detected were reconfirmed by Sanger sequencing. The clinicopathological features were investigated and two heterozygous missense variants were identified: R452W, not previously associated with ALS, present in one of the four conserved C terminal domains in ANXA11 and R208W in SIGMAR1, respectively. Both of these variants were predicted to be damaging by pathogenicity prediction tools and various in silico methods. Conclusion: Our study revealed two potentially pathogenic variants in two ALS candidate genes. The genetic makeup of ALS patients from India has been the subject of a few prior studies, but none of them examined ANXA11 and SIGMAR1 genes so far. These results establish the framework for additional research into the pathogenic processes behind these variations that result in sporadic ALS disease and further our understanding of the genetic makeup of Indian ALS patients.

Generation of an Induced pluripotent stem cell (iPSC) line (IGIBi011-A) from a Spinocerebellar ataxia type 12 gait dominant patient.

The PPP2R2B gene, expressed highly in the brain, harbours trinucleotide CAG repeats in the 5'UTR region, in the range of 7-42 repeats. Individuals carrying CAG repeats greater than 43 have been associated to manifest a neurodegenerative disease condition termed as Spinocerebellar Ataxia type 12 (SCA12). An iPSC line from an adult male diagnosed with SCA12 presenting symptoms of gait (Gait Dominance) was generated. It showed pluripotency and trilineage markers without any chromosomal abnormality. This line can be utilized as an essential resource in enhancing our understanding of the molecular pathogenic mechanisms underlying SCA12 by facilitating generation of various neuronal cell types.

Generation of two human induced pluripotent stem cell lines, IGIBi012-A and IGIBi013-A from Friedreich's ataxia (FRDA) patients with homozygous GAA repeat expansion in FXN gene.

Friedreich's ataxia is a neurodegenerative disorder caused by the hyper expansion of (GAA-TTC)n triplet repeats in the first intron of the FXN gene. Here, we generated iPSC lines from two individuals with FRDA, both of whom have homozygous GAA repeat expansion in the first intron of FXN gene. Both iPSC lines demonstrated characteristics of pluripotency, including expression of pluripotency markers, stable karyotypes and ability to develop into all three germ layers, and presence of GAA repeat expansion with reduced FXN mRNA expression. These iPSC lines will serve as invaluable tools for investigating the pathophysiology and phenotypes of FRDA.

Investigation of RFC1 tandem nucleotide repeat locus in diverse neurodegenerative outcomes in an Indian cohort.

An intronic bi-allelic pentanucleotide repeat expansion mutation, (AAGGG)400-2000, at AAAAG repeat locus in RFC1 gene, is known as underlying genetic cause in cases with cerebellar ataxia, neuropathy, and vestibular areflexia syndrome (CANVAS) and late-onset sporadic ataxia. Biallelic positive cases carry a common recessive risk haplotype, "AAGA," spanning RFC1 gene. In this study, our aim is to find prevalence of bi-allelic (AAGGG)exp in Indian ataxia and other neurological disorders and investigate the complexity of RFC1 repeat locus and its potential association with neurodegenerative diseases in Indian population-based cohorts. We carried out repeat number and repeat type estimation using flanking PCR and repeat primed PCR (AAAAG/AAAGG/AAGGG) in four Indian disease cohorts and healthy controls. Haplotype assessment of suspected cases was done by genotyping and confirmed by Sanger sequencing. Blood samples and consent of all the cases and detailed clinical details of positive cases were collected in collaboration with A.I.I.M.S. Furthermore, comprehension of RFC1 repeat locus and risk haplotype analysis in Indian background was performed on the NGS data of Indian healthy controls by ExpansionHunter, ExpansionHunter Denovo, and PHASE analysis, respectively. Genetic screening of RFC1-TNR locus in 1998 uncharacterized cases (SCA12: 87; uncharacterized ataxia: 1818, CMT: 93) and 564 heterogenous controls showed that the frequency of subjects with bi-allelic (AAGGG)exp are 1.15%, < 0.05%, 2.15%, and 0% respectively. Two RFC1 positive sporadic late-onset ataxia cases, one bi-allelic (AAGGG)exp and another, (AAAGG)~700/(AAGGG)exp, had recessive risk haplotype and CANVAS symptoms. Long normal alleles, 15-27, are significantly rare in ataxia cohort. In IndiGen control population (IndiGen; N = 1029), long normal repeat range, 15-27, is significantly associated with A3G3 and some rare repeat motifs, AGAGG, AACGG, AAGAG, and AAGGC. Risk-associated "AAGA" haplotype of the original pathogenic expansion of A2G3 was found associated with the A3G3 representing alleles in background population. Apart from bi-allelic (AAGGG)exp, we report cases with a new pathogenic expansion of (AAAGG)exp/(AAGGG)exp in RFC1 and recessive risk haplotype. We found different repeat motifs at RFC1 TNR locus, like AAAAG, AAAGG, AAAGGG, AAAAGG, AAGAG, AACGG, AAGGC, AGAGG, and AAGGG, in Indian background population except ACAGG and (AAAGG)n/(AAGGG)n. Our findings will help in further understanding the role of long normal repeat size and different repeat motifs, specifically AAAGG, AAAGGG, and other rare repeat motifs, at the RFC1 locus.

Widening the clinical, radiological and genetic spectrum of autosomal recessive ataxia of Charlevoix-Saguenay in Indian patients.

BACKGROUND: Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS), classically presenting as a triad of early-onset cerebellar ataxia, lower extremity spasticity and peripheral neuropathy, is caused by mutations in SACS gene which encodes the protein sacsin. OBJECTIVE: To provide new insight into the occurrence of SACS mutations in South India. METHODS: Patients with three cardinal features of ARSACS-peripheral neuropathy, cerebellar ataxia, and pyramidal tract signs were included. Nine patients were clinically identified and genetically evaluated. Mutation screening of SACS by targeted sequencing of 40 recessive ataxia genes panel by next-generation sequencing was conducted. Additional investigations included magnetic resonance imaging (MRI), fundoscopy, optical coherence tomography (OCT) and nerve conduction studies (NCS). Functional disability was assessed by the Spinocerebellar Degeneration Functional Score. RESULTS: Two hundred and fifteen cerebellar ataxia patients were screened, and 9 patients with cerebellar ataxia with spasticity, peripheral neuropathy and MRI brain characteristics, consistent with a clinical diagnosis of ARSACS were identified, of which 7 patients were identified to have mutation in the SACS gene and are detailed hereafter. Age of presentation ranged from 20 to 55 years (29.8 ± 11.9) with a mean disease duration of 12.7 years (SD-7.65, range 5-22 years). All except one had onset of symptoms in the form of an ataxic gait noticed before 20 years of age. Additional features were subnormal intelligence (4/7), slow and hypometric saccades (1/7), seizures (1/7), kyphoscoliosis (1/7) and dysmorphic facies (1/7). SDFS was 3 in 5/7 patients signifying moderate disability with independent ambulation. MRI showed cerebellar atrophy with predominant atrophy of the superior vermis (7/7), horizontal linear T2 hypointensities in the pons(7/7), hyperintensities where lateral pons merges with the middle cerebellar peduncle (MCP) (7/7) well seen in fluid-attenuated inversion recovery (FLAIR) images, thickening of MCP (3/7), symmetric lateral thalamic hyperintensities (6/7), posterior fossa arachnoid cyst (4/7),thinning of posterior mid-body of corpus callosum (7/7), marginal mineralisation of the basal ganglia (7/7), bilateral parietal atrophy (7/7) and thinning of corticospinal tract on diffusion tensor imaging (DTI) (7/7). We identified pathogenic homozygous frameshift mutations in the SACS gene in six patients (including two siblings), while one patient had a heterozygous pathogenic deletion. CONCLUSIONS: This is the largest series of genetically confirmed ARSACS patients from India highlighting the clinical, ophthalmological, imaging and genetic features of this cohort.

Generation and characterization of two human iPSC lines, IGIBi014-A and IGIBi015-A, from Friedreich's ataxia (FRDA) patients with pathogenic (GAA/TTC)n repeat expansion in first intron of the Frataxin (FXN) gene.

Friedreich's ataxia (FRDA) is a rare neurodegenerativedisorder caused by over expansion of GAA repeats in thefirstintron ofFXN gene. Here, we generated two iPSC lines from FRDA patients with biallelic expansion of GAA repeats in the first intron ofFXNgene.IGIBi014-A and IGIBi015-Aboth iPSC lines demonstrated characteristics of pluripotency, normal karyotypes (46, XY),the capacity to differentiate into all three germ layers, and the ability to sustain the GAA repeat expansion with decreased FXN mRNA expression. These cell lines will be utilized to comprehend the pathophysiology of the illness and the FRDA's predictive phenotypes.

Adhatoda vasica and Tinospora cordifolia extracts ameliorate clinical and molecular markers in mild COVID-19 patients: a randomized open-label three-armed study.

BACKGROUND: SARS-CoV-2 infections caused mild-to-moderate illness. However, a sizable portion of infected people experience a rapid progression of hyper-inflammatory and hypoxic respiratory illness that necessitates an effective and safer remedy to combat COVID-19. METHODS: A total of 150 COVID-19-positive patients with no to mild symptoms, between the age groups 19-65 years were enrolled in this randomized, open-labeled three-armed clinical trial. Among them, 136 patients completed the study with RT-PCR negative reports. The patients received herbal drugs orally (Group A (Adhatoda vasica; AV; 500 mg; n = 50); Group B (Tinospora cordifolia; TC; 500 mg; n = 43), and Group C (AV + TC; 250 mg each; n = 43)) for 14 days. Clinical symptoms, vital parameters, and viral clearance were taken as primary outcomes, and biochemical, hematological parameters, cytokines, and biomarkers were evaluated at three time points as secondary outcomes. RESULTS: We found that the mean viral clearance time was 13.92 days (95% confidence interval [CI] 12.85-14.99) in Group A, 13.44 days (95% confidence interval [CI] 12.14-14.74) in Group B, and 11.86 days (95% confidence interval [CI] 10.62-13.11) days in Group C. Over a period of 14 days, the mean temperature in Groups A, and B significantly decreased linearly. In Group A, during the trial period, eosinophils, and PT/INR increased significantly, while monocytes, SGOT, globulin, serum ferritin, and HIF-1α, a marker of hypoxia reduced significantly. On the other hand, in Group B hsCRP decreased at mid-treatment. Eosinophil levels increased in Group C during the treatment, while MCP-3 levels were significantly reduced. CONCLUSIONS: All the patients of the three-armed interventions recovered from COVID-19 and none of them reported any adverse effects from the drugs. Group C patients (AV + TC) resulted in a quicker viral clearance as compared to the other two groups. We provide the first clinical report of AV herbal extract acting as a modifier of HIF-1α in COVID-19 patients along with a reduction in levels of ferritin, VEGF, and PT/INR as the markers of hypoxia, inflammation, and thrombosis highlighting the potential use in progression stages, whereas the TC group showed immunomodulatory effects. Trial registration Clinical Trials Database -India (ICMR-NIMS), CTRI/2020/09/028043. Registered 24th September 2020, https://www.ctri.nic.in/Clinicaltrials/pdf_generate.php?trialid=47443&EncHid=&modid=&compid=%27,%2747443det%27.

The molecular mechanisms of spinocerebellar ataxias for DNA repeat expansion in disease.

Spinocerebellar ataxias (SCAs) are a heterogenous group of neurodegenerative disorders which commonly inherited in an autosomal dominant manner. They cause muscle incoordination due to degeneration of the cerebellum and other parts of nervous system. Out of all the characterized (>50) SCAs, 14 SCAs are caused due to microsatellite repeat expansion mutations. Repeat expansions can result in toxic protein gain-of-function, protein loss-of-function, and/or RNA gain-of-function effects. The location and the nature of mutation modulate the underlying disease pathophysiology resulting in varying disease manifestations. Potential toxic effects of these mutations likely affect key major cellular processes such as transcriptional regulation, mitochondrial functioning, ion channel dysfunction and synaptic transmission. Involvement of several common pathways suggests interlinked function of genes implicated in the disease pathogenesis. A better understanding of the shared and distinct molecular pathogenic mechanisms in these diseases is required to develop targeted therapeutic tools and interventions for disease management. The prime focus of this review is to elaborate on how expanded 'CAG' repeats contribute to the common modes of neurotoxicity and their possible therapeutic targets in management of such devastating disorders.

Breakdown of Arabidopsis thaliana thioredoxins and glutaredoxins based on electrostatic similarity-Leads to common and unique interaction partners and functions.

The reversible reduction and oxidation of protein thiols was first described as mechanism to control light/dark-dependent metabolic regulation in photosynthetic organisms. Today, it is recognized as an essential mechanism of regulation and signal transduction in all kingdoms of life. Proteins of the thioredoxin (Trx) family, Trxs and glutaredoxins (Grxs) in particular, catalyze thiol-disulfide exchange reactions and are vital players in the operation of thiol switches. Various Trx and Grx isoforms are present in all compartments of the cell. These proteins have a rather broad but at the same time distinct substrate specificity. Understanding the molecular basis of their target specificity is central to the understanding of physiological and pathological redox signaling. Electrostatic complementarity of the redoxins with their target proteins has been proposed as a major reason. Here, we analyzed the electrostatic similarity of all Arabidopsis thaliana Trxs, Grxs, and proteins containing such domains. Clustering of the redoxins based on this comparison suggests overlapping and also distant target specificities and thus functions of the different sub-classes including all Trx isoforms as well as the three classes of Grxs, i.e. CxxC-, CGFS-, and CC-type Grxs. Our analysis also provides a rationale for the tuned substrate specificities of both the ferredoxin- and NADPH-dependent Trx reductases.

Amplicon-Based Nanopore Sequencing of Patients Infected by the SARS-CoV-2 Omicron (B.1.1.529) Variant in India.

We report the sequencing of SARS-CoV-2 Omicron variants from 75 patients, using nanopore long-read sequencing chemistry. These data show a range of mutations in spike glycoprotein that are both unique and common to other populations.

6q13q14.3 Microdeletion Syndrome with Severe Hypotonia and Facial Dysmorphism: Genotype-Phenotype Correlation.

Hypotonia is a symptom of diminished tone of skeletal muscle and can be nongenetic or a part of genetic syndrome. Hypotonia, developmental delay, and facial dysmorphism are nonspecific findings observed in many genetic syndromes mostly in chromosomal microdeletion and duplication. Here we report a case with severe hypotonia and facial dysmorphism, diagnosed with deletion at 6q13q14.3 by array comparative genomic hybridization (CGH) at very early age. Recent genetic diagnostic technologies such as array CGH may enable clinicians to diagnose chromosomal abnormalities earlier and provide appropriate medical management.