Some people have no fingerprints. That might be handy in a burglary but it can be an issue when passing through immigration or in security situations where a fingerprint is required, like getting a notary public to take your five bucks for some benign document.
Like DNA, fingerprints are unique to each person or set of identical twins. That makes them a valuable identification tool for everything from crime detection to international travel. But what happens when the tips of our fingers are missing those distinctive patterns of ridges?
The condition is known as adermatoglyphia and it is extremely rare but defects that stem from any one genetic mutation give researchers unique insights into the most complex biological phenomena, such as the consequences of lacking a single protein.
Adermatoglyphia became colloquially called "Immigration Delay Disease" when it came to the attention of the medical community after it did just that — a Swiss woman had difficulty entering the United States because non-citizens must be fingerprinted upon entry.
Only four documented families are known to suffer from the disease worldwide but it is also linked to a reduction in the number of sweat glands and researchers were concerned it may be a warning sign of more severe disorders so Prof. Eli Sprecher from Tel Aviv University decided to investigate.
Scientists know that fingerprints are fully formed 24 weeks after fertilization, and do not change throughout our lives. But "the factors underlying the formation and pattern of fingerprints during embryonic development are largely unknown," says Sprecher, who adds that it isn't only fingertips that have patterned skin — palms, toes, and the soles of the feet also feature these ridges, called dermatoglyphs.
To determine the cause of this rare condition, the researchers did a genetic analysis of the Swiss family, nine of whom have no fingerprints. They compared the genes of those with adermatoglyphia and those without to identify where the genetic alteration lies. They discovered that a skin-specific version of the gene SMARCAD1 has a regulating factor on fingerprint development. The group that presented with adermatoglyphia were found to have decreased levels of the short skin-specific version of the gene.
Now that SMARCAD1 has been identified, researchers will be able to further investigate how the gene regulates fingerprint development. Adermatoglyphia is interesting, and can certainly be a curiosity for border security, it turns out to be non-threatening, despite the minor issue of the hand's inability to produce sweat.
This research was carried out in collaboration with Dr. Janna Nousbeck of the Tel Aviv Sourasky Medical Center and Prof. Peter Itin of the University Hospital at Basel, Switzerland. The findings have been published in the American Journal of Human Genetics.