The Role of Molecular Testing

Molecular testing is an umbrella term for techniques that look for specific biomarkers—like genes or proteins—in the RNA and DNA of your body’s cells. Molecular tests can be used to diagnose disease or guide treatment by identifying the most effective medications for a particular condition.

The field of molecular testing has expanded significantly in the past decade. It is now routine in many clinical laboratories, and it can provide valuable information to doctors and other health care providers. However, molecular testing is complex and carries with it certain risks.

When molecular tests are performed correctly, they offer greater certainty after a doctor has made a tentative diagnosis. This can reduce the number of unnecessary invasive procedures that may be performed, such as surgical lobectomies for indeterminate thyroid nodules. Molecular testing also can help physicians determine the best treatments, such as immunotherapy for some cancers or a fecal microbiota transplant to introduce healthy bacteria to the patient’s gastrointestinal tract.

Most often, molecular tests are used to identify genetic mutations that increase a person’s risk for certain diseases. For example, the BRCA1 and BRCA2 genes are associated with hereditary breast and ovarian cancer syndrome, and testing for these mutations can enable a woman to take preventive measures to lower her risk of developing the disease. Molecular tests also can be used to identify biomarkers that suggest a patient’s cancer will respond to a particular drug. For example, a tumor’s PIK3CA and HER2 gene changes can suggest the patient will benefit from tyrosine kinase inhibitors, which are drugs that target the molecular mechanism of the tumor and effectively treat it.

Another important role of molecular testing is to detect infectious agents in a sample of body fluid or tissue. Cleared CLIA-waived molecular tests can be used in physician offices to test for respiratory viruses, such as influenza A and B, RSV, human metapneumovirus, adenoviruses, parainfluenza 1-4, and coronaviruses OC43, 229E, NL63, and HKU1, as well as group A streptococcus (Table 195.2). Read more here: https://www.jantdx.com.

However, despite the many benefits of molecular testing, it’s important for laboratory professionals to recognize its limitations. For instance, a molecular test that uses polymerase chain reaction (PCR) to amplify the targeted nucleic acid can produce millions or billions of copies of the targeted sequence. This can result in false-positive results. In addition, it’s critical that the cellularity of a sample submitted for molecular testing be sufficient to perform the assay, since most tests require a high concentration of nucleic acid.

The Centers for Disease Control and Prevention offers a tool that helps medical laboratories determine whether they can perform molecular testing based on the cellularity of the specimen. CLSI also offers guidelines on sampling, transport, preparation, and storage of specimens for molecular testing. To get more enlightened on this topic, then click on this related post: https://en.wikipedia.org/wiki/Molecular_diagnostics.