Although their physiological role remains obscure, fingerprints (epidermal ridges) are characteristic of the human skin. They are widely used for identity check because their morphology remains permanent without any modification from their establishment at 24 weeks post-fertilization throughout lifespan.
Individuals completely missing fingerprints are extremely rare, but famous for encountering difficulties entering foreign countries. That is why their condition, scientifically termed adermatoglyphia, was surnamed the "immigration delay disease".