Molecular testing looks for biomarkers in the RNA and DNA of cells to diagnose diseases like cancer or predict your risk of future disease. It’s a rapidly growing area of laboratory medicine and an important component of precision health care.
Molecular tests have been designed to detect bacterial and viral infections, evaluate cell markers (such as tumor markers), determine a person’s genetic predisposition to diseases, and identify mutations that are associated with particular diseases such as cystic fibrosis. The emergence of molecular testing has revolutionized the way clinical and public health laboratories investigate human, viral, and microbial genomes and the genes and proteins they encode. This technology is becoming a standard in many areas of laboratory medicine, including oncology, infectious diseases, clinical chemistry, and clinical genetics.
A tox analyzer typically requires a small sample of a blood or body fluid such as saliva, urine, or breast milk to be studied in a lab. The results of some tests can be obtained in as little as an hour or even minutes, while others may take a few days to weeks.
The most common types of molecular tests include polymerase chain reaction (PCR) tests, which look for specific gene mutations in a specimen by using DNA primers to generate a product that is easily detected. For example, if a fetus is homozygous for a certain mutation in the delta F508 gene that causes cystic fibrosis, a CVS (chorionic villus sample) specimen will produce two peaks when tested with an appropriate PCR assay. Homozygotes for a single mutation will yield one peak.
Other molecular tests use chromosomal microarrays or other technologies to assess the levels of gene expression in normal and diseased tissues. The results of these tests can be used to determine the type and stage of a cancer, determine whether a patient’s genes make them more likely to develop a disease, and to guide therapy by targeting treatments to those genes that are most active in the tumor.
As with any new diagnostic tool on this link, molecular tests have their limitations. One major issue is that they can return a result that provides no useful information (often referred to as uninformative, inconclusive, or ambiguous). This can happen because everyone has common, natural variations in their DNA called polymorphisms that do not affect their health and also because a mutation might be found that has not yet been confirmed to cause disease in scientific research or might be present at very low levels and therefore not be clinically significant. It is important to understand these limitations up front when discussing a molecular testing option with your physician and when receiving a test result. Often, a thorough patient discussion with a laboratory GC or geneticist can help to allay patients’ concerns about an indeterminate or complex test result. Get a general overview of the topic here: https://en.wikipedia.org/wiki/Molecular_diagnostics.
