Image caption Some people are born without fingerprints

Scientists believe they have identified the genetic flaw behind an incredibly rare condition in which people have no fingerprints.

A study published in the American Journal of Human Genetics looked at one Swiss family, many of whom have no fingerprints.

By analysing their DNA, researchers identified the SMARCAD1 gene.

Researchers said "virtually nothing" was known about how the gene functioned in the skin.

Normally fingers are covered with ridges called dermatoglyphs which are fully formed before birth.

Passport problems

Only four families have been diagnosed with the fingerprint-less condition known as adermatoglyphia.

It is more popularly referred to as "immigration delay disease" due to problems patient say they have getting through airports.

In this study, researchers from the Tel Aviv Sourasky Medical Center in Israel looked at the genetic code of 16 members of a family. Seven had fingerprints, nine were born without.

They found that a shorter version of the SMARCAD1 gene was expressed in the skin and that patients who did not have fingerprints had mutations in the gene.

The lead researcher Professor Eli Sprecher said: "Our findings implicate a skin-specific version of SMARCAD1 in the regulation of fingerprint development.

"Little is known about the function of full-length SMARCAD1 and virtually nothing regarding the physiological role of the skin-specific version of the gene".

Full length SMARCAD1 is thought to control the activity of other genes.

He added: "As abnormal fingerprints are known to sometimes herald severe disorders, our finding may also impact the understanding of additional diseases affecting not only the skin."