What is Molecular Diagnostics?

What is Molecular Diagnostics?

Healthcare Tech Outlook | Tuesday, October 05, 2021

Molecular diagnostics is becoming an intrinsic element of the clinical practice as several molecular techniques have completed their expected transformations into the clinical setting.

FREMONT, CA: Recent groundbreaking advances in human genetics are reshaping the perspective towards therapy and diagnosis. In the case of inherited genetic disease and a wide range of neoplastic and infectious processes, nucleic acid-based testing is now becoming a critical diagnostic tool. A process known as pharmacogenomics can be followed after diagnosis, where molecular testing can aid in the identification of suitable treatment by finding specific therapeutic targets for a variety of newly customized medications.

Molecular diagnostics offers the foundation for successful gene therapy and biologic response modifier applications. It's a powerful tool for determining disease prognosis and therapy response and finding minimum residual disease. It is expected that DNA or RNA analysis will account for more than 5 percent of all laboratory tests in the future.

Polymerase chain reaction and real-time PCR

Genetic rearrangements are an excellent target for several molecular diagnostic examinations in oncology since they are a natural feature of oncogenesis. Rearrangements combine the previously separated portions of the genomic DNA. By chromosomal translocations or deletions of intervening DNA regions, new fusion (chimeric) genes are generated by pushing nucleic acid sequences closer together.

In a molecular pathology laboratory, PCR is the most commonly employed molecular method. Numerous copies of a specific chimeric gene can be generated utilizing a set of priming complementary sequences (oligonucleotide primers) around a site of interest and special heat-resistant polymerases (DNA copying enzymes).

Fluorescent in situ hybridization

FISH is focused on utilizing fluorescence-labeled oligonucleotide probes that selectively connect to their corresponding DNA sequence target on the genome and fluorescence-color-code that area (e.g., Texas red, FITCI green, acridine orange). A fluorescent microscope can then easily visualize the indicated region.

FISH has significant benefits over traditional cytogenetics in the investigation of chromosomal deletions, translocations, and gene amplification. Conventional cytogenetics necessitates a lengthy cell culture phase and can only be conducted on fresh tissue samples. On the other hand, FISH can be used on both dividings (metaphase) and resting (interphase) cells.

Spectral karyotype imaging

SKI works by using 23 combinations of chromosome-specific "painting" probes. Each probe contains variable amounts of three fluorescent dyes, allowing every chromosome pair to be identified by a light with a particular spectrum emission. The use of an "interferometer," like the ones used by astronomers to distinguish light spectra emitted by various stars, is a critical element of this technique.

DNA microarrays

The use of DNA microarrays to profile gene expression holds a lot of potential for the future of molecular diagnostics. This approach enables the simultaneous measurement of the expression rate of multiple genes in one sample and a single test. cDNA microarrays and oligonucleotide or DNA chips are the two most common types of DNA microarrays.

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