Why Is DNA in Our Fingerprints?

Every cell of the human body, including those in your fingertips, contains DNA, or deoxyribonucleic acid. DNA, a hereditary substance found in all living organisms , is located in the cell's nucleus and can be extracted from bodily fluids, such as blood and semen, and even fingerprints, because these contain cells. The DNA found in fingerprints comes from skin cells shed upon contact with surface objects and can help scientists to compile a DNA profile.

DNA in Fingerprints

• Fingerprints contain skin cells that are shed when someone touches an external object DNA can be extracted from these cells. But while DNA can be obtained from an original fingerprint, it can't be obtained from a fingerprint copy stored for identification purposes. Canadian scientist Maria Viaznikova said that her research time yields, on average, 10 billionths of a gram of DNA from fingerprints.

Profiling

• The amount of DNA that can be collected from a fingerprint for DNA profiling varies from person to person. The number of skin cells found in a fingerprint can depend, for example, on how much someone sweats. According to the DNA Diagnostic Center, scientists using conventional profiling techniques need around 150 nucleated cells to obtain a DNA profile. If very few skin cells are available from a finger print or other DNA sample, scientists can use what known as "low copy number DNA profiling," a technique that enables them to produce a profile from a small number of cells.

Collecting DNA

• Scientists extract cells from a fingerprint using a moist swab followed by a dry swab. DNA can normally be obtained if someone touches a surface for at least 60 seconds. According to the DNA Diagnostics Center, cells are frequently obtained from surfaces such as glass mirrors and plastic and metal lids.

Considerations

• Although DNA profiling for criminal investigation and medical research purposes is usually obtained from blood or other fluid samples, extracting it from fingerprints can yield valuable evidence in criminal investigations, particularly if it is combined with forensic analysis of other DNA samples from, for example, hair and semen obtained at a crime scene.