Our scientists crack the secret of fingerprints

◎ Cen Pan Science and Technology Daily reporter Wang Chun

The skin pattern phenotype is an important part of the human appearance phenotype and, like other phenotypes in the human body, is closely related to disease. Fingerprints are concave and convex lines that exist on the skin of the fingers, and because of their constantity and high hereditability, they have become the most widely studied skin texture types. And how is the fingerprint pattern formed? Which genes play a leading role in this? Humans still know little about the biological mechanisms by which they are formed.

In order to solve the above mystery, the team of researcher Wang Sijia of the Shanghai Institute of Nutrition and Health of the Chinese Academy of Sciences, the team of Professor Denis Headon of the University of Edinburgh and the team of academician Jin Li of Fudan University carried out in-depth research on this in more than ten scientific research institutions inside and outside the United Nations, starting from the localization of genetic variations related to fingerprint pattern phenotype, and conducted genome-wide association scans and multi-population meta-analysis for more than 23,000 individuals, from which 43 genetic loci associated with human fingerprint patterns were identified.

After analyzing the relationship between millions of genetic loci and fingerprint patterns, the team pointed out that genes related to human limb development play a key role in the formation of fingerprint pattern phenotypes. This finding is also expected to provide new ideas for the study of early identification and screening of specific diseases through skin pattern phenotype. On January 7, 2022, the relevant research results were published in the first issue of "Cell" in 2022, entitled "The Basis of Limb Development Genes Constituting The Differences in Human Fingerprint Patterns".

Li Jinxi, a postdoctoral fellow at the Institute of Human Phenotypes at Fudan University and the first author of the paper, demonstrated fingerprint collection equipment. The picture is from the official website of Fudan University

"We observed that 43 genetic genes associated with human fingerprint patterns were significantly enriched in pathways related to limb development and formation, rather than skin development pathways." Wang Sijia, the paper's corresponding author, said the discovery of this feature delighted the team. Among them, the mutation site located near the EVI1 gene in the 3q26.2 region of chromosomes is significantly related to the composite phenotype of the middle three fingers, that is, the index finger, middle finger and ring finger fingerprint, thus providing a phenotymic and genetic explanation for the phenomenon of "the fingerprint of the middle three fingers is highly correlated" discovered at the beginning of the last century.

More than that, based on experimental observations of mouse animal models and human embryonic tissue, the team found that in the series of human fetal tissue from limb development to skin pattern formation, it is the mesenchymal cells expressed during limb development that support the EVI1 gene to shape limbs and fingers, rather than epithelial cells during skin development. This is further in line with the conclusion of the study: fingerprint-related genes affect the formation of fingerprint patterns by regulating limb development.

Through multi-phenotypic association analysis, the study also found a close correlation between the proportion of fingerprint pattern and finger length, and the two have the same genetic basis. For example, the longer the little finger, the shorter the palm length, the more two-handed bucket patterns, while the longer the distal knuckles of the index finger, the less the bucket pattern.

"Through this study, we revealed that what affects the formation of fingerprint patterns is a series of important genes related to limb development, which often play an important role in human development." Wang Sijia introduced that just like the "dominoes" arranged next to each other, limb development genes are the internal influencing factors of fingerprints.

Following this line of thought, this study provides an important theoretical basis for the study of the association between skin lines and other phenotypes and diseases in the human body, and is expected to open up the connection and mechanism of macroscopic and microscopic phenotypes. "At present, the scientific community has found an association between different skin patterns and many congenital genetic diseases, such as down syndrome patients may have broken palms, foot thumb toe arched spherical patterns and other features." It is reported that Wang Sijia's team is cooperating with medical institutions such as the Children's Hospital of Fudan University, hoping to apply the relevant research results to the early screening of neonatal congenital diseases as soon as possible to achieve early diagnosis and treatment. "Through a series of subsequent experiments, human phenotype research can also continue to discover and verify the scientific nature of traditional Chinese medicine theories such as 'looking, hearing, asking and cutting'." Wang Sijia introduced.

"This achievement is a classic case of human phenotype group research, which well reflects the great scientific significance of human phenomics as a new paradigm with innovative sources," commented Jin Li, co-corresponding author of the paper, academician of the Chinese Academy of Sciences and professor of Fudan University.

An important purpose of human phenotype research is to discover the mechanisms of association between genes-phenotype-environment and macro-micro phenotypes, especially "strong associations" and the mechanisms behind them. It is reported that Fudan University is working with partners at home and abroad to vigorously promote the human phenotype group big science plan, will be a considerable number of volunteer groups as much as possible, as complete as possible to collect phenotypic data, and then discover and analyze the strong association between phenotypes, especially those scientists have not noticed, closely related to human health phenotypic strong associations, and finally form a "navigation map" composed of various strong associations, providing new guidance and direction for future life and health research.

At present, after the cooperation of Chinese scientist teams from different institutions, based on the cohort study of more than 800 people in Shanghai, each measuring nearly 30,000 phenotypes, the world's first "human phenotype group navigation map" has been preliminarily drawn, and more than 1.5 million strong associations have been found, of which cross-domain strong associations account for 39%, most of which are the first discoveries in the scientific community. "This 'navigation map' has brought a huge number of 'question marks' to our scientific community, and is waiting for us scientists to further study and crack, which is also one of our important tasks in the next step." Jin Li said.

Source: Science and Technology Daily

Editor: Wang Yu

Review: Yue Liang

Final Judge: Liu Haiying