Contrary to what researchers previously thought, the shape of fingerprints is not linked to the genes of the skin, but to those responsible for the development of the limbs.
- The shape of fingerprints is linked to genes for limb growth, and in particular to the EVI1 gene.
- Fingerprint patterns are also genetically correlated to finger length.
Wavy, circular or sinuous: each human has unique fingerprints. Made up of folds of the epidermis, their shape is however not influenced by the genes responsible for the skin, but that of the limbs.
This is demonstrated by a new study published in the journal Cell by researchers from the Chinese Academy of Sciences.
“We started working out of pure curiosity, explains geneticist Sijia Wang, co-author of the study. But it turned out later that the fingerprint pattern is associated with genes for limb growth, which are essential for fetal development. This provides another classic example of pleiotropy, when several phenotypes are linked to each other and are affected by the same genes.”
The key role of the EVI1 gene
Fingerprints are classified into three types: arc, loop and whorl. These furrows and ridges of the epidermis begin to form on the fingers and toes of the fetus after the third month of pregnancy. Scientists have suspected that fingerprints have potentially evolved to help grasp objects and perceive their texture, but exactly how these patterns are formed has until now remained unknown.
To better understand how they form, researchers analyzed the DNA of more than 23,000 people from different ethnic groups and found that at least 43 regions of the genome are associated with fingerprints. One of the most influential regions seems to regulate the expression of a gene called EVI1, which plays a role in the development of embryonic limbs.
The team therefore wanted to know more about the involvement of the EVI1 gene in the formation of fingerprints. She modified the DNA of mice to reduce gene expression, and then found that they developed abnormal skin patterns on their fingers compared to unmodified mice.
The researchers also analyzed data from the human participants. They found that fingerprint patterns are genetically correlated with finger length. For example, people with whorl-shaped fingerprints on both pinkies tend to have longer pinkies than others, and this correlation is strongly linked to genes involved in limb development.
The shape of fingerprints linked to certain diseases
For now, researchers don’t know how genes shape fingerprint patterns. Geneticist Jinxi Li, who also led the study, says: “This could be determined by the growth force exerted on an embryonic tissue called the palmar pad, which plays an important role in forming the different fingerprint patterns.” She explains that as the hands of a fetus grow, the palms and fingers stretch and lengthen. These forces could turn a vortex into a loop, for example.
This discovery on fingerprints could make it possible to learn more about certain diseases. Previous studies have, for example, suggested that the EVI1 gene is linked to the risk of leukemia. And “many congenital genetic disorders are linked to different dermatoglyphic patterns, such as fingerprints”, emphasizes Dr. Wang. For example, children with Down syndrome are more likely to have a single crease on the palms of their hands. “Our study suggests that dermatoglyphic patterns are affected by crucial developmental genes, providing a strong theoretical basis for this type of pleiotropy.” This will be the subject of future work by the research team.
.
