Molecular testing is a broad category of tests that look for molecules in your DNA or other pieces of genetic information called RNA to diagnose a disease like cancer or predict your risk of future diseases. These molecules might be genes, proteins, or other biomarkers.

Molecular tests have replaced conventional tests in many fields of medicine. Some of their uses include:

  • helping plan treatment
  • finding out if treatment is working
  • estimating your outlook
  • predicting whether your cancer will come back or has spread

Read on to learn more about molecular testing, including how it works, its uses, and the different types.

Molecular testing is a field of diagnostic medicine that has undergone rapid development in recent years.

A molecular diagnostic test analyzes the genetic information in your DNA and RNA by examining a tissue sample to look for specific disease markers. The tissue sample might be:

  • blood
  • saliva
  • urine
  • feces
  • specific organ tissue

DNA comprises long strands of molecules that contain all your genetic information. DNA is in the nucleus of every cell in your body, and its structure resembles a twisted ladder. If a cell were a restaurant, DNA would be like the cookbook that contains all the restaurant’s recipes.

RNA is a strand of genetic material outside the nucleus that tells the functional structures in the cell what to do. Using the restaurant analogy, RNA is like a copy of an individual recipe in the cookbook that each restaurant cook receives.

A molecular test analyzes changes in these two types of molecules to look for red flags that might indicate a current or future disease.

Molecular testing has many uses. Here are just some of them.

Molecular testing for cancer

Molecular testing can identify genes with links to certain cancers. For example, mutations in the BRCA1or BRCA2 genes have links to hereditary breast and ovarian cancer syndrome.

Molecular tests can also help identify biomarkers that suggest that certain treatments might be more effective. For example, certain changes in the EGFR gene can help doctors determine if EGFR inhibitors might effectively treat lung cancer.

Molecular testing for COVID-19

Molecular testing for COVID-19 involves using a technique called reverse transcription polymerase chain reaction (RT-PCR). This test can better inspect pieces of the SARS-CoV-2 virus to see if you have COVID-19. These tests are typically more accurate than antigen tests that look for proteins your immune system produces to defend against COVID-19.

Molecular HPV testing

Molecular human papillomavirus (HPV) tests involve analyzing pieces of viral DNA to see whether they contain HPV. There are a variety of tests available that scientists can use to check for HPV.

Molecular testing for disease markers

Genetic tests can look for mutations or variations in your DNA linked to the development of certain diseases. This is useful if you have genetic conditions running in your family to see if you inherited the genes. For example, inherited changes in the genes LDLR, APOB, and PCSK9 have links to familial hypercholesterolemia.

Other Infectious diseases

Scientists can use molecular tests to diagnose respiratory, gastrointestinal, and central nervous infections. Some tests can detect more than 20 infectious organisms, such as viruses or bacteria, in about an hour.

Other uses

Molecular tests have many other purposes, including:

The are several different types of molecular tests, such as:

Molecular PCR testing

A polymerase chain reaction (PCR) test is a specific type of molecular test used to amplify specific sections of DNA for a wide range of purposes, such as:

Kary B. Mullis developed the PCR method in the early 1980s and won the Nobel Prize in Chemistry in 1993 for this invention. PCR tests fall into a larger group of tests called nucleic acid amplification tests (NAATs).

Other NAATs

Other types of NAATs can help diagnose infectious diseases. Besides PCR, other testing techniques include:

  • clustered regularly interspaced short palindromic repeats (CRISPR)
  • helicase-dependent amplification (HDA)
  • loop-mediated isothermal amplification (LAMP)
  • nicking endonuclease amplification reaction (NEAR)
  • strand displacement amplification (SDA)
  • transcription-mediated amplification (TMA)

Rapid molecular testing

Rapid molecular tests can produce results very quickly. For example, molecular tests for influenza can detect upper respiratory tract infections in 15 to 30 minutes.

Commercial at-home tests

Many types of molecular tests are now available as home tests where you can send the samples to a laboratory for analysis. Examples include home COVID-19 and ancestry genetic tests, such as 23andMe and AncestryDNA.

Antibiotic susceptibility testing

Doctors sometimes order antibiotic susceptibility testing to see which drugs will be the most effective, especially when drug-resistant organisms are prevalent.

Current testing techniques require 2 days to 1 week for results. While awaiting the results, the doctor will likely prescribe you the highest recommended antibiotic for your specific infection.

Genetic tests

Genetic tests help identify changes in your genetic information linked to certain diseases. Types of genetic tests include:

  • Targeted single variant tests: These tests look for one specific gene. For example, they can detect the HBB gene that determines sickle cell anemia.
  • Single variant: Single variant tests look for a change in any one gene.
  • Gene panel: A gene panel can identify changes in multiple genes.
  • Whole genome sequencing. These tests examine most of your DNA to find gene variations linked to disease.

Providing a sample for a molecule test can be very quick. For example, receiving a nasal swab result for COVID-19 may take less than a minute. Most samples require laboratory analysis. The results of some tests are available in as little as an hour, while others might take 1 to 3 days.

Some rapid tests can provide results in as little as 15 to 30 minutes.

The field of molecular diagnostic testing is growing rapidly. Its role in precision medicine will likely continue to grow.

In precision medicine, doctors use biomarkers to develop an individually tailored treatment plan for a disease. For example, two people with the same type of cancer might have different responses to the same treatment based on the presence or absence of certain gene mutations.

According to the National Cancer Institute, precision medicine isn’t part of routine cancer care for most people, but researchers are making daily progress.

Promising research is underway examining how the microbiome in your gut influences your health and whether manipulating it can aid help with the diagnosis and treatment of disease.

Molecular testing will likely play an important role in the future development of treatments like fecal microbiota transplants. This treatment involves transplanting donated stool from one person to another to introduce beneficial bacteria.

Molecular testing includes a wide range of tests that look for biomarkers in the RNA and DNA of your cells. They have many applications, such as helping doctors diagnose infections or helping them choose the best treatment for a condition.

The field of molecular testing is rapidly growing and is likely to play an increasingly important role in medicine as more individually tailored disease treatments become mainstream.