Articles Written By Deepak Kumar, PhD

Developing variant calling and analysis pipelines for NGS sequenced data have become a norm in clinical labs. These pipelines include a strategic integration of several tools and techniques to identify molecular and structural variants. That eventually helps in the apt variant annotation and interpretation. This blog will delve into the concepts and intricacies of developing a “variant calling” pipeline using GATK. “Variant calling” can also be performed using tools other than GATK, such as FREEBAYES and SAMTOOLS.  In this blog, I will walk you through variant calling methods on Illumina germline RNASeq data. In the steps, wherever required, I will…

Clinical trials are studies designed to test the novel methods of diagnosing and treating health conditions – by observing the outcomes of human subjects under experimental conditions.  These are interventional studies that are performed under stringent clinical laboratory settings. Contrariwise, non-interventional studies are performed outside the clinical trial settings that provide researchers an opportunity to monitor the effect of drugs in real-life situations. Non-interventional trials are also termed observational studies as they include post-marketing surveillance studies (PMS) and post-authorization safety studies (PASS). Clinical trials are preferred for testing newly developed drugs since interventional studies are conducted in a highly monitored…

In the first blog of this series, we explored the power of sequencing the genome at various levels. We also dealt with how the characterization of the RNA expression levels helps us to understand the changes at the genome level. These changes impact the downstream expression of the target genes. In this blog, we will explore how NGS sequencing can help us comprehend DNA modification that affect the expression pattern of the given genes (epigenetic profiling) as well as characterizing the DNA-protein interactions that allow for the identification of genes that may be regulated by a given protein.  DNA Methylation Profiling…

Why is Next Generation Sequencing so powerful to explore and answer both clinical and research questions. With the ability to sequence whole genomes, identifying novel changes between individuals, to exploring what RNA sequences are being expressed, or to examine DNA modifications and protein-DNA interactions occurring that can help researchers better understand the complex regulation of transcription. This, in turn, allows them to characterize changes during different disease states, which can suggest a way to treat said disease.  Over the next two blogs, I will highlight these different methods along with illustrating how these can help clinical diagnostics as well as…

NGS methodologies have been used to produce high-throughput sequence data. These data with appropriate computational analyses facilitate variant identification and prove to be extremely valuable in pharmaceutical industries and clinical practice for developing drug molecules inhibiting disease progression. Thus, by providing a comprehensive profile of an individual’s variome — particularly that of clinical relevance consisting of pathogenic variants — NGS helps in determining new disease genes. The information thus obtained on genetic variations and the target disease genes can be used by the Pharma companies to develop drugs impeding these variants and their disease-causing effect. However simple this may allude…

Single Nucleotide Variant (SNVs) have been considered as the main source of genetic variation, therefore precisely identifying these SNVs is a critical part of the Next Generation Sequencing (NGS) workflow. However, in this report from 2004, the authors identified another form of variants called the Structural Variants (SVs), which are genetic alterations of 50 or more base pairs, and result in duplications, deletions, insertions, inversions, and translocations in the genome. The changes in the DNA organization resulting from these SVs have been shown to be responsible for both phenotypic variation and a variety of pathological conditions. While the average variation,…

After genome assembly (covered in my previous blog) comes the vital step of gene prediction and annotation. This step entails the prediction of all the genes present in the assembled genome and to provide efficient functional annotation to these genes from the data available in diverse public repositories; such as Protein Family (PFAM), SuperFamily, Conserved Domain Database (CDD), TIGRFAM, PROSITE, CATH, SCOP, and other protein domain databases. It is imperative to understand that prediction and annotation of non-protein-coding genes, Untranslated Regions (UTR), and tRNA are as vital as protein-coding genes to determine the overall genetic constitution of the assembled genome. …

The main goal for researchers, clinicians, and students who perform Next Generation Sequencing (NGS) and produce sequenced data for diverse projects involving human samples is to find biomarkers or variants to make diagnoses; and deduce the genetic anomalies that could be responsible for the disease they are conducting research on. Most projects (academic or non-academic) constitute the prior ideology on deciphering the “unknown.” There are well-versed computational protocols and pipelines formulated by labs across the world in determining what the “unknown” variants are. The fact that we have the “reference” human genome available – thanks to the Human Genome Project – plays…

Next Generation Sequencing (NGS) is a rapidly evolving and widely used method worldwide in both academic and non-academic settings. One of the most valuable aspects of NGS is producing millions of sequenced reads with diverse read lengths from small amounts of input DNA. NGS methods are extremely versatile; producing reads as short as 75 bp, as seen in SOLiD sequencing, to long reads ranging upwards of 1000bp in the case of Pyrosequencing.  Both long and short reads fill a unique niche for researchers. Longer reads generated from NGS are excellent for genomic rearrangement and genome assembly projects; especially when there…