A biomarker is a molecule, gene, or characteristic that is an indicator of a normal or abnormal biological process, or of a particular disease state. Biomarkers can be used to measure the progress of a disease, to predict the likelihood of developing a disease, or to monitor the response to treatment.
There are many different types of biomarkers, and they can be classified in several ways. One common classification scheme divides biomarkers into “prognostic” and “diagnostic” categories. Prognostic biomarkers are those that predict the likelihood of developing a disease, while diagnostic biomarkers are those that indicate the presence of a disease.
Another common way to classify biomarkers is by their origin: “endogenous” markers are produced by the body itself, while “exogenous” markers come from outside the body. Endogenous markers are usually more specific for particular diseases than exogenous markers; however, exogenous markers may be easier to measure.
still other classification schemes exist; for example, some have proposed dividing biomarkers into those that measure exposure (to a risk factor), those that measure effect (of exposure on health), and those that predicting susceptibility (to developing a disease). However, these various classification schemes are not always mutually exclusive; for example, many prognostic biomarkers also fall into the category of exposure markers.
The use of biomarkers in medicine is becoming increasingly important as we learn more about the molecular basis of diseases and as we develop new technologies for measuring them. Biomarkers offer great promise for earlier detection of diseases, improved diagnosis, and targeted therapies tailored specifically to an individual’s unique physiology. As our understanding of biology improves and our technology gets better at measuring small changes in biomolecules, it is likely that biomedical researchers will discover ever more uses for this powerful tool.