Why Do We Have Fingerprints?

fingerprint-dime-d-sharon-pruitt

A patient of mine with severe hand dermatitis has an identity problem. She applied for a job that she is well qualified to get, except she doesn’t have any fingerprints. Her job requires a security clearance, and she has to have fingerprints to verify her identity (and to verify that she isn’t wanted in Montana). But her severe hand dermatitis has left her fingertips scarred, and she is unable to give adequate fingerprints.

Why do we have fingerprints in the first place? The ridges are unique and allow you to be distinguished from billions of other people. Although wonderful for the FBI, your fingerprints were never meant to assist in identifying you.

It has been traditionally thought that the tiny ridges increase the coefficient of friction of the skin making it easier to grasp and hold things. A smooth surface makes handling delicate objects like a dime, difficult, especially if your hands are wet.

New research suggests that the grooves have another, possibly more important function: they improve your sense of touch. Fingertips are exquisitely sensitive to touch. This is partly due to a special nerve called the Pacinian corpuscle. The tips of your fingers are packed with these sensitive receptors. One sensation that they are particularly attuned to is vibration. It turns out that the ridges on your fingertips when rubbed against an object create a  fine vibration that is not noticeable to you, but is detected by your Pacinian corpuscles.

Loss of fingerprints is uncommon. It can happen from trauma, as from a burn, or from chronic skin diseases such as eczema, psoriasis, or scleroderma. There are also rare genetic conditions such as dyskeratosis congenital, an inherited condition that leads to scaly skin and increased risk of skin cancers, where patients are born without fingerprints.

Excess inflammation, as from dermatitis or psoriasis, can sometimes lead to temporary changes in the fingerprints. These changes can be resolved with topical steroids or other systemic medications to treat the underlying condition. Once the fingerprint is scarred, however, there is no way to regenerate it.

Post written by Dr. Benabio Copyright The Derm Blog 2009

Photo: D. Sharon Pruitt (flickr)