Mutated DNA Causes No-Fingerprint Disease

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A genetic mutation causes people to be born without fingerprints, a new study says.

Almost every person is born with fingerprints, and everyone's are unique. But people with a rare disease known as adermatoglyphia do not have fingerprints from birth. Affecting only four known extended families worldwide, the condition is also called immigration-delay disease, since a lack of fingerprints makes it difficult for people to cross international borders.

In an effort to find the cause of the disease, dermatologist Eli Sprechers equenced the DNA of 16 members of one family with adermatoglyphia in Switzerland. Seven had normal fingerprints, and the other nine did not. After investigating a number of genes to find evidence of mutation, the researchers came up empty-handed—until a grad student finally found the culprit, a smaller version of a gene called SMARCAD1. (Get a genetics overview.)

The larger SMARCAD1 is expressed throughout the body, but the smaller form acts only on the skin. Sure enough, the nine family members with no fingerprints had mutations in that gene.

Being born without fingerprints doesn't occur simply because one gene has been turned on or off, Sprecher said. Rather, the mutation causes copies of the SMARCAD1 gene to be unstable.

That mutation is also the first link in a long chain of events that ultimately affects fingerprint development in the womb. The rest of the links in the chain are still a mystery, said Sprecher, of the Tel Aviv Sourasky Medical Center.

(See skin pictures.)

No-Fingerprint Disease Not Harmful

Other inherited diseases that result in a lack of fingerprints—such as Naegeli syndrome and dermatopathia pigmentosa reticularis—are caused by problems with the protein keratin-14.

(Related: "Born Without Fingerprints: Scientists Solve Mystery of Rare Disorder.")

These conditions "manifest not only with lack of fingerprints, but also with a number of other critical features—a thickening of the skin, problems with nail formation," Sprecher said.

By contrast, immigration-delay disease doesn't come with any side effects besides a minor reduction in the ability to sweat. In general, people with the disease "are otherwise completely healthy, like you and me."

By further studying the Swiss family, Sprecher said, it might be possible to solve the mystery of fingerprints overall.

"You go from a rare disease to a biological insight of general importance," he said. "We would never have been able to get to this gene if not for the study of this family."

The fingerprint research was published August 12 in the American Journal of Human Genetics.

First Genetic Evidence Of Long-Lived African Presence Within Britain

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New research has identified the first genetic evidence of Africans having lived amongst "indigenous" British people for centuries. Their descendants, living across the UK today, were unaware of their black ancestry.

The University of Leicester study, funded by the Wellcome Trust and published today in the journal European Journal of Human Genetics, found that one third of men with a rare Yorkshire surname carry a rare Y chromosome type previously found only amongst people of West African origin.

The researchers, led by Professor Mark Jobling, of the Department of Genetics at the University of Leicester, first spotted the rare Y chromosome type, known as hgA1, in one individual, Mr. X. This happened whilst PhD student Ms. Turi King was sampling a larger group in a study to explore the association between surnames and the Y chromosome, both inherited from father to son. Mr. X, a white Caucasian living in Leicester, was unaware of having any African ancestors.

"As you can imagine, we were pretty amazed to find this result in someone unaware of having any African roots," explains Professor Jobling, a Wellcome Trust Senior Research Fellow. "The Y chromosome is passed down from father to son, so this suggested that Mr. X must have had African ancestry somewhere down the line. Our study suggests that this must have happened some time ago."

Although most of Britain's one million people who define themselves as "Black or Black British" owe their origins to immigration from the Caribbean and Africa from the mid-twentieth century onwards, in reality, there has been a long history of contact with Africa. Africans were first recorded in the north 1800 years ago, as Roman soldiers defending Hadrian's Wall.

To investigate the origins of hgA1 in Britain, the team recruited and studied a further eighteen males with the same surname as Mr. X. All but one were from the UK, with paternal parents and grandparents also born in Britain. Six, including one male in the US whose ancestors had migrated from England in 1894, were found to have the hgA1 chromosome.

Further genealogical research to identify a common ancestor for all seven X-surnamed males suggests that the hgA1 Y chromosome must have entered their lineage over 250 years ago. However, it is unclear whether the male ancestor was a first generation African immigrant or a European man carrying an African Y chromosome introduced into Britain some time earlier, or even whether the hgA1 Y chromosome goes back as far as the Roman occupation.

"This study shows that what it means to be British is complicated and always has been," says Professor Jobling. "Human migration history is clearly very complex, particularly for an island nation such as ours, and this study further debunks the idea that there are simple and distinct populations or 'races'."

In addition, Professor Jobling believes that the research may have implications for DNA profiling in criminal investigations.

"Forensic scientists use DNA analysis to predict a person's ethnic origins, for example from hair or blood samples found at a crime scene. Whilst they are very likely to predict the correct ethnicity by using wider analysis of DNA other than the Y chromosome, finding this remarkable African chromosome would certainly have them scratching their heads for a while."