How Are Our Fingerprints Formed?

How Are Our Fingerprints Formed?

In the most comprehensive analysis ever conducted, scientists discovered that the genes responsible for the development of the limbs, rather than the formation of the skin, affect fingerprint shapes. These genes make our fingerprints circular, wavy, or sinuous. The findings, presented yesterday in Cell, may help to better understand the relationship between genes and phenotypic traits in humans.

“People may be wondering why our team is working on fingerprints,” says geneticist Sijia Wang, lead author of the paper, from the Shanghai Institute of Nutrition and Health of the Chinese Academy of Sciences. “We started this work out of pure curiosity. But then it turned out that the fingerprint pattern is associated with limb development genes, which are of great importance in the development of the fetus. This is a classic example of pleiotropy, where multiple phenotypes are related and influenced by the same genes.”

Although fingerprints are different for everyone, they are generally grouped into three classes: rounded, looped and spiral. These grooves and ridges begin to form on the fingers and toes of the fetus after the third month of pregnancy. Exactly how these patterns formed remains a mystery, although scientists think fingerprints may have evolved to help them grasp objects and sense the texture of objects.

Scanning the DNA of more than 23,000 people from many ethnic groups, Wang and colleagues discovered that at least 43 regions in the genome were associated with fingerprint patterns. One of the most influential regions was found to regulate the expression of the EVI1 gene, which is known for its role in limb development in the embryo.

To test their findings, the researchers modified the mice’s DNA, as a result of which they turned off the expression of the EVI1 gene in mice. They discovered that the fingers of mice with the EVI1 gene turned off developed abnormal skin patterns compared to wild mice.

By analyzing data from humans, fingerprint patterns were found to exhibit a genetic relationship to finger length. For example, people with spiral-shaped fingerprints on both pinkies tend to have longer pinkies than people without such a print. This link displays a strong link with genes associated with limb development.

“We don’t know exactly how genes shape fingerprint patterns,” says Jinxi Li, a geneticist at Fudan University’s Human Phenomen Institute in Shanghai and co-first author of the study. “However, this process may be determined by the amount of force that growth exerts on an embryonic tissue called the volar base, which plays an important role in the formation of different fingerprint patterns.” Li explains that as a fetus’s hands grow, so will their palms and fingers. These forces can transform a spiral pattern into a loop pattern, for example.

Another interesting point is that EVI1 has been associated with the risk of leukemia in previous studies. Wang says that some studies have observed that people with more spiral patterns are more prone to this disease.

“Many inborn genetic diseases are associated with different dermatoglyphic patterns, like fingerprints,” he says. For example, children with Down syndrome are more likely to have a single crease on their hands that extends across the palm. “Our work suggests that developmental genes of major importance influence dermatoglyphic patterns and provide a strong theoretical foundation for such pleiotropies.”

The new research is part of the International Human Phenomena Project led by Fudan University, Shanghai, which aims to reveal how phenotypic traits in humans are interconnected. The research team’s next goal is to conduct further research into how dermatoglyphic patterns are associated with disease and underlying pleiotropic functioning.


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