|MadSci Network: Medicine|
We know that fingerprints are specific for each individual and that no two persons have the same fingerprints.Having this in mind then do identical twins who are genotypically identical (nature's way of cloning) have the same fingerprints?
The contribution of genetics to fingerprints, especially regarding identical twins' fingerprints, has already been discussed on this site (check these answers by Lynn Bry and Leslie Gartner), as has the importance of fingerprints to us as animals, and the development of fingerprints in the embryo. To sum up: identical twins have essentially identical fingerprints, so genetics play the major role in their formation.
If they do not, this means that fingerprints are not coded by genes so if they are not gene controlled then how come when one gets a cut or abrasion on his/her hand or finger the same fingerprints resume after the wound has healed itself?
Actually, the answer is more complex than genetics. While it's true that fingerprints are essentially genetically determined, this determination occurs in utero during development of the skin of the embryo. During early development, the "skin" of the embryo is a single layer of cells called the ectoderm. Later in development, cells from the mesoderm and neural crest form layers just below the ectoderm and form the dermis (connective tissue) and melanocytes (pigment cells), respectively. Formation of the dermis requires chemical cues from the ectoderm, just as differentiation of the ectoderm into skin requires chemical cues from the underlying dermis. The ripples that form fingerprints are generated by adjusting these chemical cues in a pattern that is written into the connective tissue of the dermis. But the pattern has to be established all at once, such that after the skin is formed, the pattern is hard-wired into the dermis.
So, a simple cut of a shallow abrasion results in the skin using this pattern to reform the print. However, any trauma that damages the dermis, like a bad burn or a deep injury, will destroy the pattern in that area, and a deformed (randomized) print will result when the skin grows back over the injury. It is even possible, though extremely painful, to erase your fingerprints by burning your fingertips - I did this accidentally to my right middle finger when I was a child, and I still have a disordered blotch in the middle of that print. Of course that just makes my fingerprint that much more distinct, since the blotch is more random than simple whorls and arches. So, fingerprints are determined by the genome of the embryo, however the ability to reform fingerprints after skin damage is not controled by the genes but by the pattern of the dermis.
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