One bucket is poor, two buckets is rich? Your fingerprints actually hold these secrets

"One dou means poverty, two dou means wealth, three dou and four dou means selling tofu..." As the saying goes, the "dou" (circular lines) and "boji" (non-circular lines) on fingerprints hide the codes of wisdom and wealth, and even determine a person's wealth or poverty.

A new study by a research team from Fudan University and the Shanghai Institute of Nutrition and Health of the Chinese Academy of Sciences shows that although fingerprints have nothing to do with wealth or poverty, they may contain health signals. Skin texture is affected by key limb development genes and is related to growth, development and disease.

On January 7, the related research was published in the first issue of Cell in 2022, which will help to better decipher the connection between human genes and phenotypic characteristics.

Amazing finger "patterns"

Fingerprints are the uneven lines on the skin of the fingers. Because they are so common, the genetic code behind them has not received much attention.

“In the beginning, this work was undertaken out of pure curiosity.”

"But we later discovered that fingerprint patterns are related to limb growth genes, and limb growth is crucial for fetal development," Wang Sijia, a co-author of the paper and a researcher at the Shanghai Institute of Nutrition and Health of the Chinese Academy of Sciences, told China Science Daily.

As the research deepens, scientists find that there are more and more mysteries to be solved: How are human fingerprint patterns formed? Which genes play a leading role in it? Is there a biological mechanism for the formation of phenotypes such as fingerprints?

To solve these mysteries, Wang Sijia's team, Professor Denis Headon's team at the University of Edinburgh, and Academician Jin Li's team at Fudan University, in collaboration with more than ten scientific research institutions at home and abroad, conducted in-depth research on this issue. By analyzing a large sample population, they accurately quantified the fingerprint patterns of multi-ethnic groups.

After analyzing the relationship between millions of genetic loci and fingerprint patterns, they found that genes related to human limb development played a key role in the formation of fingerprint pattern phenotypes.

"The shape of the fingerprint - whether it is a bucket or a dustpan - is affected by the genes responsible for limb development," Wang said. "This is a typical example of multiple phenotypes being interrelated and affected by the same genes."

Fingerprint patterns are usually divided into three types: arches, loops and spirals. These "grooves" and "ridges" begin to form on the fingers and toes three months after the fetus is formed. Scientists suspect that the evolution of fingerprints may help grasp objects and perceive their textures, but it is unknown how these patterns are formed.

Genes “control” fingerprints

In order to find out which genes are related to the fingerprint pattern phenotype and the genetic mechanism behind it, the researchers started from the genetic variations related to the fingerprint pattern phenotype, conducted whole-genome association scans and multi-population meta-analyses on more than 23,000 individuals, and identified 43 genetic loci related to human fingerprint patterns.

"We observed that these genes were significantly enriched in pathways related to limb development and formation, rather than pathways related to skin development," said Wang Sijia.

The team was delighted by the discovery.

To verify these findings, the researchers conducted experimental observations based on mouse animal models and human embryonic tissues, and found that in the series of processes from limb development to skin striae formation in human fetal tissues, it is the mesenchymal cells expressed during the limb development period, rather than the epithelial cells during the skin development period, that support the EVI1 gene to play a role in shaping limbs and fingers.

This further confirms the research conclusion: fingerprint-related genes affect the formation of fingerprint patterns by regulating limb development.

Through multi-phenotype association analysis, researchers found that fingerprint patterns are closely related to the ratio of finger length, and the two share the same genetic basis. For example, the longer the little finger is, the shorter the palm length is, and the more bucket-shaped patterns there are on both hands; while the longer the distal knuckle of the index finger (where the fingerprint is formed) is, the fewer bucket-shaped patterns there are.

New paradigm brings "navigation map"

"We don't know how fingerprint patterns are genetically determined, but it could be determined by the forces of growth on the palm pad of the embryonic tissue, which plays an important role in the formation of different fingerprint patterns."

"As the fetus's hand grows, the palm and fingers stretch and lengthen," said Li Jinxi, one of the first authors of the paper and a postdoctoral fellow at the Institute of Human Phenome and School of Life Sciences at Fudan University. "For example, these forces can turn a spiral pattern into a loop."

"It is worth noting that previous studies have shown that EVI1 is associated with the risk of leukemia." Wang Sijia gave an example, "The scientific community has found the association between different dermatoglyphic phenotypes and many congenital genetic diseases. For example, people with Down syndrome may have features such as broken palms and arched ball patterns on the big toes."

Wang Sijia believes that this study provides an important theoretical basis for the study of the association between skin texture and other phenotypes and diseases of the human body, and is expected to open up the connection and mechanism of action between macroscopic and microscopic phenotypes, making it possible to "identify diseases by looking at hands."

Currently, Wang Sijia's team is cooperating with medical institutions such as the Children's Hospital Affiliated to Fudan University, hoping to apply the relevant research results to the early screening of congenital diseases in newborns as soon as possible, so as to achieve early diagnosis and early treatment.

"This is a classic case of human phenotype research, which well demonstrates that human phenotype research, as a new paradigm, has great scientific significance as a source of innovation." Jin Li, co-corresponding author of the paper, academician of the Chinese Academy of Sciences and professor at Fudan University, told China Science Daily.

At present, a team of Chinese scientists from different institutions have worked together to preliminarily draw the world's first "Human Phenotype Group Navigation Map" based on a cohort study of more than 800 people conducted by Fudan University in Shanghai, with nearly 30,000 phenotypes measured for each person. They have discovered more than 1.5 million strong correlations, of which 39% are strong cross-domain correlations, most of which are discovered for the first time in the scientific community.

"This 'navigation map' has brought a lot of 'questions' to the scientific community, waiting for scientists to further study and solve them," Jin Li said. "This is also one of our next work focuses."

Source: China Science Daily

Author:Xu Rui

Related paper information:

https://doi.org/10.1016/j.cell.2021.12.008

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