Linkage Disequilibrium in Targeted Sequencing

We propose an approach for optimizing the development of gene diagnostic panels, which is based on the construction of non-equilibrium linkage maps. In the process of gene selection we essentially use genome-wide association analysis (GWAS). Whole-genome analysis of associations makes it possible to reveal the relationship of genomic variants with the studied phenotype. However, the nucleotide variants that showed the highest degree of association can only be statistically associated with the phenotype, not being the true cause of the phenotype. In this case, they may be in the block of linked inheritance with nucleotide variants that really affect the manifestation of the phenotype. The construction of maps of non-equilibrium linkage of nucleotides makes it possible to optimally determine the boundaries of linkage blocks, in which the desired variants fall. The aim of this study was to optimize the demarcation of genomic loci to create targeted panels aimed at predicting susceptibility to SARS-CoV-2 and the severity of COVID-19. The proposed method for selecting loci for a target panel, taking into account nonequilibrium linkage, makes it possible to use the phenomenon of nonequilibrium linkage in order to maximally cover the regions involved in the development of the phenotype, while simultaneously minimizing the length of these regions, and, at the same time, the cost of sequencing © 2022, Mathematical Biology and Bioinformatics.All Rights Reserved.

Linkage Disequilibrium in Targeted Sequencing

We propose an approach for optimizing the development of gene diagnostic panels, which is based on the construction of non-equilibrium linkage maps. In the process of gene selection we essentially use genome-wide association analysis (GWAS). Whole-genome analysis of associations makes it possible to reveal the relationship of genomic variants with the studied phenotype. However, the nucleotide variants that showed the highest degree of association can only be statistically associated with the phenotype, not being the true cause of the phenotype. In this case, they may be in the block of linked inheritance with nucleotide variants that really affect the manifestation of the phenotype. The construction of maps of non-equilibrium linkage of nucleotides makes it possible to optimally determine the boundaries of linkage blocks, in which the desired variants fall. The aim of this study was to optimize the demarcation of genomic loci to create targeted panels aimed at predicting susceptibility to SARS-CoV-2 and the severity of COVID-19. The proposed method for selecting loci for a target panel, taking into account nonequilibrium linkage, makes it possible to use the phenomenon of nonequilibrium linkage in order to maximally cover the regions involved in the development of the phenotype, while simultaneously minimizing the length of these regions, and, at the same time, the cost of sequencing © 2022, Mathematical Biology and Bioinformatics.All Rights Reserved.

Targeted Sequencing Approach and Its Clinical Applications for the Molecular Diagnosis of Human Diseases.

The outbreak of COVID-19 has positively impacted the NGS market recently. Targeted sequencing (TS) has become an important routine technique in both clinical and research settings, with advantages including high confidence and accuracy, a reasonable turnaround time, relatively low cost, and fewer data burdens with the level of bioinformatics or computational demand. Since there are no clear consensus guidelines on the wide range of next-generation sequencing (NGS) platforms and techniques, there is a vital need for researchers and clinicians to develop efficient approaches, especially for the molecular diagnosis of diseases in the emergency of the disease and the global pandemic outbreak of COVID-19. In this review, we aim to summarize different methods of TS, demonstrate parameters for TS assay designs, illustrate different TS panels, discuss their limitations, and present the challenges of TS concerning their clinical application for the molecular diagnosis of human diseases.

Rapid Identification of Drug Resistance and Phylogeny in M. tuberculosis, Directly from Sputum Samples.

Tuberculosis (TB) remains one of the most important infectious diseases globally. Establishing a resistance profile from the initial TB diagnosis is a priority. Rapid molecular tests evaluate only the most common genetic variants responsible for resistance to certain drugs, and Whole Genome Sequencing (WGS) needs culture prior to next-generation sequencing (NGS), limiting their clinical value. Targeted sequencing (TS) from clinical samples avoids these drawbacks, providing a signature of genetic markers that can be associated with drug resistance and phylogeny. In this study, a proof-of-concept protocol was developed for detecting genomic variants associated with drug resistance and for the phylogenetic classification of Mycobacterium Tuberculosis (Mtb) in sputum samples. Initially, a set of Mtb reference strains from the WHO were sequenced (WGS and TS). The results from the protocol agreed >95% with WHO reported data and phenotypic drug susceptibility testing (pDST). Lineage genetics results were 100% concordant with those derived from WGS. After that, the TS protocol was applied to sputum samples from TB patients to detect resistance to first- and second-line drugs and derive phylogeny. The accuracy was >90% for all evaluated drugs, except Eto/Pto (77.8%), and 100% were phylogenetically classified. The results indicate that the described protocol, which affords the complete drug resistance profile and phylogeny of Mtb from sputum, could be useful in the clinical area, advancing toward more personalized and more effective treatments in the near future. IMPORTANCE The COVID-19 pandemic negatively affected the progress in accessing essential Tuberculosis (TB) services and reducing the burden of TB disease, resulting in a decreased detection of new cases and increased deaths. Generating molecular diagnostic tests with faster results without losing reliability is considered a priority. Specifically, developing an antimicrobial resistance profile from the initial stages of TB diagnosis is essential to ensure appropriate treatment. Currently available rapid molecular tests evaluate only the most common genetic variants responsible for resistance to certain drugs, limiting their clinical value. In this work, targeted sequencing on sputum samples from TB patients was used to identify Mycobacterium tuberculosis mutations in genes associated with drug resistance and to derive a phylogeny of the infecting strain. This protocol constitutes a proof-of-concept toward the goal of helping clinicians select a timely and appropriate treatment by providing them with actionable information beyond current molecular approaches.

Genetic variants associated with the occurrence and progression of adolescent idiopathic scoliosis: a systematic review protocol.

BACKGROUND: Adolescent idiopathic scoliosis (AIS) is a structural lateral spinal curvature of ≥ 10° with rotation. Approximately 2-3% of children in most populations are affected with AIS, and this condition is responsible for approximately $1.1 billion in surgical costs to the US healthcare system. Although a genetic factor for AIS has been demonstrated for decades, with multiple potentially contributory loci identified across populations, treatment options have remained limited to bracing and surgery. METHODS: The databases MEDLINE (via PubMed), Embase, Google Scholar, and Ovid MEDLINE will be searched and limited to articles in English. We will conduct title and abstract, full-text, and data extraction screening through Covidence, followed by data transfer to a custom REDCap database. Quality assessment will be confirmed by multiple reviewers. Studies containing variant-level data (i.e., GWAS, exome sequencing) for AIS subjects and controls will be considered. Outcomes of interest will include presence/absence of AIS, scoliosis curve severity, scoliosis curve progression, and presence/absence of nucleotide-level variants. Analyses will include odds ratios and relative risk assessments, and subgroup analysis (i.e., males vs. females, age groups) may be applied. Quality assessment tools will include GRADE and Q-Genie for genetic studies. DISCUSSION: In this systematic review, we seek to evaluate the quality of genetic evidence for AIS to better inform research efforts, to ultimately improve the quality of patient care and diagnosis. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration #CRD42021243253.

Bordetella avium-associated endophthalmitis: case report.

BACKGROUND: Bordetella avium, an aerobic bacterium that rarely causes infection in humans, is a species of Bordetella that generally inhabits the respiratory tracts of turkeys and other birds. It causes a highly contagious bordetellosis. Few reports describe B. avium as a causative agent of eye-related infections. CASE PRESENTATION: We report a case of acute infectious endophthalmitis associated with infection by B. avium after open trauma. After emergency vitrectomy and subsequent broad-spectrum antibiotic treatment, the infection was controlled successfully, and the patient's vision improved. CONCLUSIONS: B. avium can cause infection in the human eye, which can manifest as acute purulent endophthalmitis. Nanopore targeted sequencing technology can quickly identify this organism. Emergency vitrectomy combined with lens removal and silicone oil tamponade and the early application of broad-spectrum antibiotics are key for successful treatment.