A
molecular marker is a
molecule contained within a sample taken from an
organism (
biological markers) or other matter. It can be used to reveal certain characteristics about the respective source.
DNA, for example, is a molecular marker containing information about
genetic disorders,
genealogy and the
evolutionary history of life. Specific regions of the DNA (
genetic markers) are used to diagnose the
autosomal recessive genetic disorder
cystic fibrosis,
taxonomic affinity (
phylogenetics) and
identity (
DNA Barcoding). Further,
life forms are known to shed unique chemicals, including
DNA, into the
environment as evidence of their presence in a particular location. Other
biological markers, like
proteins, are used in
diagnostic tests for complex
neurodegenerative disorders, such as
Alzheimer's disease. Non-biological molecular markers are also used, for example, in
environmental studies.