Transcriptomics

Transcriptomics is the analysis of the transcriptome, the collection of all ribonucleic acid (RNA) that is present in a sample (a cell, tissue or organ) at a given time. RNA performs many functions within the cell, and studying the transcriptome provides insights into how genes are working and whether proteins are being produced as expected.

What is it? How could it help? Ready for patients? In humans, DNA segments are Cancer: GEP tests which examine GEP tests are already in use in copied into RNA in a process a subset of RNAs have shown the clinic, with many more in called transcription, allowing a promise in understanding development. These are cheaper cell to act on the ‘instructions’ prognosis and guiding treatment and easier to perform than encoded in the DNA genome. decisions in cancer and are carrying out whole transcriptome Different types of RNA have already used for this purpose in analysis using RNA-seq, which different roles: messenger RNA breast cancer. is costly and complex to perform (mRNA) is produced during gene and interpret, but is useful as a expression as an intermediary Rare disease: Clinical research research tool to identify potential between DNA and proteins, while studies are examining the utility new targets for GEPs. other non-protein coding RNAs of performing transcriptome RNA-seq has potential as a impact on a variety of cellular analysis alongside whole genome diagnostic assay, particularly functions. A cell’s transcriptome is or exome sequencing (WGS/WES) in settings such as rare disease constantly changing depending on in rare disease. Transcriptomics is where disease-relevant targets its needs. showing promise in improving the are hard to identify and validate. number of diagnoses made. Transcriptomics can either refer to However clinical implementation exploratory analysis of the entire requires the provision of specific Infectious disease: Analysis transcriptome, primarily using sequencing technologies, the of gene expression patterns in RNA sequencing (RNA-seq), or to ability to perform the required patients is being investigated targeted analysis of known RNAs bioinformatics analysis, and the as a novel tool to assist in the using techniques such as gene need to store large amounts of diagnosis and management of expression panels (GEPs). data. infectious disease, for example distinguishing between bacterial and viral infections, and predicting the severity of sepsis. Outlook Targeted RNA tests are currently the most suitable form of transcriptome analysis for clinical use, and in many cases RNA-seq may be most useful as a tool to inform the development of these tests. Whilst RNA-seq has the potential to itself be a powerful tool for diagnosing certain conditions, it is not ready to be used routinely on patients and its utility remains to be assessed. The 100,000 Genomes Project has retained some samples for future transcriptome analysis, which should inform the future clinical implementation of transcriptomics.

Authors: Joanna Janus and Emma Johnson [email protected]