Why do some people look younger than their age while others look older? Chinese scientists have published research results that show for the first time that premature facial aging is associated with a very specific gene. This gene is responsible for the production of dark pigment and is believed to be the cause of the appearance of the Caucasian white race. The relationship between mutations and the aging of the faces of white Europeans was understood by "Lenta.ru".
Everyone wants to look younger than their age. This is due to the belief that youth is a reflection of health. Indeed, as recent studies by British and Danish scientists have shown, external age can predict a person's lifespan. External age appears to correlate with biomolecular markers such as telomere length. Understanding the mechanisms that underlie changes in appearance, according to gerontologists - experts in aging, is vital for the development of new methods of anti-aging therapies, but there is not enough research in this area.
Comparison of two averaged faces obtained from photographs of 22 women 70 years old, whose external age is 59 years (A), and photographs of 22 women 70 years old, whose external age is 80 years (B), taking into account the effect of wrinkles.
Image: Fan Liu et al. Chinese Academy of Sciences
An international team of scientists from research institutes in China, the Netherlands, the UK and Germany conducted a large-scale study to find genome-wide associations to find the relationship between genes and external age, including the severity of facial wrinkles. Geneticists studied the genomes of more than two thousand elderly Britons, participants in the Rotterdam study, dedicated to identifying factors that cause cardiovascular, neurological, ophthalmological and mental disorders in people of advanced age. Scientists have tested more than eight million single nucleotide polymorphisms (SNP) for connection with external age.
Comparison of two averaged faces obtained from photographs of 22 women 69 years old, whose external age is 60 years, and photographs of 22 women 69 years old, whose external age is 78 years (D), excluding the effect of wrinkles.
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Image: Fan Liu et al. Chinese Academy of Sciences
A snip occurs when one of the nucleotides in a gene or on another piece of DNA is replaced by another. In fact, this is a mutation that creates a new variant of a gene or, in the language of geneticists, a new allele. One allele can differ from another by several snips. Often, snips do not affect anything, since they affect not so important parts of DNA, but sometimes a mutation can have a harmful or beneficial effect, for example, accelerate or slow down the aging of the facial skin. How to find the desired mutation among millions of others? The task of a genome-wide search for associations is to divide the participants into several groups - with younger and older individuals, and find out which of the single-nucleotide substitutions these groups differ the most. The most common snip (or some of the most common) will be in the same genewhat is responsible for external age.
Geneticists examined 2,693 people to find SNPs associated with the rate of facial aging, the severity of wrinkles, changes in skin color, face shape, lip size, jawline and nasolabial folds. Although the scientists did not find sufficiently reliable associations with external age and wrinkles, they noticed that various single nucleotide substitutions in the MC1R gene, which is located on chromosome 16, are more common. However, if the influence of biological age and sex is taken into account in the analysis, a reliable association between MC1R alleles immediately emerges. Since every healthy person has a double set of chromosomes, which means that each gene is presented in two copies, then if in cells one MC1R gene is normal and the other is mutant, the person looks one year older than his age, if both MC1R are mutant - by two years … Note thatthat the mutant gene in this case means that allele that does not produce a normal protein.
Manhattan graph, which shows that the MC1R locus is most closely related to external age. The horizontal line shows the loci of different genes, and the vertical line shows the degree of association with age characteristics.
Image: Fan Liu et al. Chinese Academy of Sciences
To test their findings, biologists used the results of another long-term study, taking genetic data from 599 elderly Danes. Scientists estimated the external age and severity of wrinkles from photographs of people whose biological age was known. An association was found with single nucleotide polymorphisms that were in close proximity to MC1R or within this gene. But the geneticists did not stop there and did another test, this time with 1173 Europeans, of whom 99 percent are women. External age was still associated with MC1R.
What is so special about MC1R? The gene encodes a type 1 melanocortin receptor protein, which is involved in signaling pathways leading to the production of the dark pigment eumelanin. Early research showed that 80 percent of people with red hair or fair skin have an MC1R variant that produces a non-working protein. Snips in this gene are also associated with the manifestation of age spots. Interestingly, skin color has some effect on the degree of association between alleles and external age. In people with pale skin, this connection is strongest, and it is weakest of all with an olive complexion, however, despite this, the association still remained significant.
Overall, the effect of MC1R on external age was evident regardless of skin color or age spots, indicating other facial features that may be responsible for the association. Since the mutant alleles result in yellow and red pigments that are unable to protect the skin from the damaging and aging UV radiation, the sun could influence external age. However, even with this influence, the association is still strong. The authors of the article believe that MC1R may interact with other genes involved in inflammatory and oxidative processes. Further research is needed to uncover the biochemical and molecular mechanisms underlying skin aging.
Alexander Enikeev