b'Chapter 1 Understanding molecular genetic diagnostic methodsPeter Friebe, PhDMolecular diagnostics (MDx) is a field of laboratory medicineConsumers are now more educated; terms like PCR, antigen which applies molecular biology techniques to study humantests, and antibodies are widely understood. A diagnostic disease. MDx applications target sequences of human andconsumerism has begun as patients not only expect easy microbial genomes, as well as the proteins they encode, toaccess to testing but also transparency in how the test works and assess a patients health at the molecular level. Such methodswhat the results mean.can be used to identify genetic biomarkers, germline and somaticWith so many new developments, understanding the differences variations, infectious pathogens, and monitor progression ofand nuances between MDx technologies and platforms can be disease. Since the dawn of recombinant DNA technology,dauntingeven for healthcare professionals. This article takes a monumental accomplishments in life science technologies suchcloser look at some of the most widely utilized molecular genetic the invention of polymerase chain reaction (PCR), breakthroughstesting technologies, their workflows (Figure 1) and applications. in next-generation sequencing, and the completion of the Human Genome Project, have accelerated this field of study.Nucleic acid isolationAs innovation marches on, innovative technologies continueNucleic acid extraction is generally required for both sequencing to push towards more accurate, rapid, cost-effective, andas well as NAAT (nucleic acid amplification tests) testing, as high-throughput methods for molecular analysis and diagnosis. the targeted genetic material is often embedded in cells, viral The COVID-19 outbreak accelerated MDx innovation by bridgingparticles, or otherwise shielded in a way that interferes with basic research and clinical reality with new devices andthe test. Cells, proteins and other molecules in the collected technologies to answer urgent needs in clinical management.specimen milieu or the collection/transport medium can also The pandemic created a nearly universal acceptance of MDxcontain inhibitors. Sample preparation is therefore a critical step at various levels, from global health organizations, public andfor most MDx techniques, and the extraction technology must be private companies, schools, hospitals, physicians, and patientssuitable for the given sample type (blood, urine, feces, saliva, etc. to anyone wanting a fast and reliable COVID-19 test result.as well as the designated nucleic acid (DNA, RNA, or both).Figure 1. Schematic workflow of qPCR and next-generation sequencing (NGS) testing.4 Molecular testing thermofisher.com/infectiousdisease Contents'