What is molecular diagnostics?

Molecular diagnostics is a branch of diagnostics that exploits the tools and knowledge of fields such as molecular biology, genetics, microbiology and biochemistry to understand the basis of disease in patients. It is  based on the ability to detect the presence of and/or read the sequence of genetic material i.e. the nucleic acids DNA and RNA, and is applicable to most major categories of medical disorders. Some examples of applications of molecular diagnostics are:

  • Infectious diseases: Detection, identification, and quantification of infectious disease agents like bacteria, viruses, fungi and determination of antimicrobial resistance status if necessary.
  • Oncology: (a) Estimation of risk of being affected by cancer or having a recurrence and, (b) tailoring of treatment based on the genetic profile of the cancer.
  • Inherited genetic disorders: Diagnosis of genetic disorders such as thalassemias, Down Syndrome, Prader Willi  Syndrome and muscular dystrophies.

In addition to the primary applications listed above, other medical areas also fall under the broad category of molecular diagnostics. The following are some of the typical applications of molecular diagnostics.

What are the advantages of molecular diagnostics?

Molecular diagnostics directly looks for the causative agent (in the case of infectious disease) or variations in genetic patterns (in case of non-infectious diseases) rather than looking at the effects of the disease. This allows more sensitive, specific and rapid detection, and in some cases allows detection where none was possible before. This can be illustrated through these examples:

  • For infectious diseases: Rapid identification of the causative agent of a disease whether it is a bacterium, virus, fungus or protozoan with an indication on the level of infection, and information on what drugs it will be sensitive and resistant to. This allows the doctor to act on that information within hours rather than days as they do currently. Particularly important in ICU infections where it can mean the difference between life and death, not to mention the cost of increased stay in the ICU.
  • For cancer: Detection of predictive risk (e.g in familial cancers which can then enable different levels of intervention based on the risk), selection of appropriate therapy and dosing based on the molecular type of the cancer and the genetic makeup of the patient (i.e. higher success of chemotherapy and lower side effects).
  • For pre-natal diagnostics: Diagnosis of amniotic or chorionic villus samples, or even non-invasive diagnosis of cell free fetal DNA from maternal blood, from pregnant women who are at high risk to have children with anomalies like Down Syndrome, etc; especially useful in families that have a genetic history of disorders, or who have lost a child or sibling or who are at a relatively advanced age at the time of pregnancy.