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Dark secrets of DNA. Scientists talk about dangerous types of marriage

Scientists sequenced the genome of a man buried in a Stone Age tomb at Newgrange in Ireland and found that he was born as a result of incest. Marriages between close relatives were almost always prohibited due to the threat of degeneration. However, there is a risk of accidental incest. How dangerous it is from the point of view of genetics?

Power sealed in blood

For biological and cultural reasons, incest has been taboo since ancient times. They violated the ban in exceptional cases for the sake of strengthening power. Probably, the discovery of Irish scientists in Newgrange is connected with this – with the formation of the ruling elite in prehistoric society.

Dynastic marriages between relatives and cousins ​​were concluded in Ancient Egypt, the Inca empire, in the royal families of the Hawaiian archipelago. It once symbolized the purity of blood.
The majority of Iceland’s 360,000 inhabitants are descendants of several Viking groups who settled on the island in the 9th century.

The population is genetically very homogeneous. A few years ago, local company deCode Genetics even released an app based on a DNA test database to prevent young people from accidentally marrying a close relative.

DNA rushes to the rescue

Computer programs have been developed that compare a set of certain regions of the genome and determine the degree of relationship. Genealogical research is generally very popular now. People do DNA tests, upload the results to public databases such as Ancestry and Gedmach, and find relatives. First of all, those who do not know their origin: raised in orphanages, adopted.

Sometimes this kind of research brings unpleasant surprises. So, an American gave her husband a DNA test for his birthday. The results shocked the spouses: they turned out to be first-order cousins ​​on the father’s side. Moreover, the couple already had a two-year-old child. The woman spoke about this a year ago in the podcast of the American publication Slate.

Scientists immediately warned that sperm donation is fraught with accidental incest, and recommended strictly limiting the number of children conceived by one donor. In 2011, The New York Times reported 150 half-brothers and sisters. In 2017, the British press raised the issue of countries like Nigeria where the legislative regulation of this area is weak. Last year in the United States, there was a lot of discussion about the story of Dr. Kline, who tricked female clients of a reproductive clinic with his own sperm. Nearly five dozen of his biological children have found each other through public DNA testing databases.

How dangerous are “dynastic ties”

Children of incestuous marriages are twice as likely to get hereditary pathology. They have a higher risk of rare genetic diseases (orphan diseases) caused by recessive alleles – variants of genes whose activity is usually suppressed.

“Both spouses can inherit a recessive mutant allele from a common ancestor. They are healthy, but they have a heterozygous genotype, that is, with this allele. The probability that such a couple will have a sick child with a homozygous genotype is 25 percent,”.


If both parents carry an X chromosome with a mutant gene, then the risk of passing them on to both children increases to 25%. This situation often develops in closely related marriages.

In this case, medical genetic counseling is necessary in order to reduce the risk of passing on the genetic pathology to the child. Experts take into account everything: the degree of kinship, the state of health of family members, other kinship marriages in previous generations, ethnicity, since some hereditary diseases accumulate in certain ethnic groups.

“During pregnancy, you can undergo prenatal genetic diagnostics in order to obtain the most accurate data on the genetic material of the child,”.

Meanwhile, according to various estimates, about a billion people live in closed communities, where closely related marriages are not uncommon and even encouraged. For example, in Egypt, men could only marry if they had a home. Accordingly, the problem was solved by marriage between relatives living under the same roof – as a rule, cousins.

“In southern India, more than 52 percent of marriages are between cousins ​​and second cousins. Many nationalities have lived like this for thousands of years and have not disappeared from the face of the earth because of a rare recessive gene associated with any disease,”.

A person is able to adapt to almost any situation, Sosin believes. The most serious pathologies that are not compatible with life are eliminated even at the zygote stage – when the germ cells merge or the first few divisions of the embryo. If the pathology is not fatal, the child can be born.

Scientists give an example – Turkey, where marriages between cousins ​​and sisters are very common. Infant mortality is high there, and among the elderly it is common in countries with similar income and social security levels. This phenomenon is called the “Turkish puzzle”.

“In 1968, 27 percent of marriages in Turkey were concluded by close relatives. In 2008, 24. Studies have shown that, in general, first-degree marriages, that is, between a cousin and a sister, increase infant mortality by 45 percent. This is another insurance policy. , through which nature removes from the equation of life children who are not able to exist physically fully, “.

However, it is incorrect to deduce a certain average value of the risk of pathologies in closely related marriages. Each case is unique. It is especially difficult with multifactorial diseases, the causes of which remain unclear. By the way, they can be ecological, rooted in the way of life. For example, schizophrenia. Parents with this diagnosis have a 29 percent risk of transmitting the pathology to their child, and 41 percent if they are close relatives. According to some reports, children born in a marriage between a cousin and a sister have slightly worse IQ scores (by 0.8-1.3 points).

On the Internet, they write that in closely related marriages, almost half of the children are with hereditary pathologies. In fact, Sosin emphasizes, much less. According to various estimates, from one to nine percent, when it comes to parents who are each other’s first generation cousins.

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Science & Technology

20 scientific predictions for the next 10 years

We are lucky to be born and live in an incredible time of development of science and technology. We know the approximate rate of development of both, but we have no idea what this rate will be by the end of our life. Things that have long been considered science fiction are becoming components of our lives every day. In the next ten years, the world may present us with gifts that cannot be refused.

The amazing thing about all these scientific discoveries is that they give rise to technologies that further accelerate technological progress. Our ability to innovate grows exponentially as the years go by. 

To give you an idea of ​​the significance of this progression, here are 20 scientific predictions that should occur by 2030.

1. Artificial intelligence (AI) will pass the Turing test, or in other words, the machine will prove that it can think independently.

2. Hyperloop (Elon Musk’s vacuum train project) will start passenger transportation.

3. Biosensors will go on sale, which will call an ambulance if the wearer suddenly becomes ill. In addition, they will remind you to take certain medications, assessing the current state of the body.

4. The level of air pollution will rise, but scientists will come closer to an effective solution to this global problem.

5. Self-driving car will remain a luxury.

6. The world average cost of solar panels will drop sharply, the transition to solar energy will be very rapid.

7. People will return to the moon and begin its consistent colonization.

8. Robots-killers (drones with weapons) will appear. Crime will reach a fundamentally new level. Investigations will come to a standstill.

9. In developed countries, life expectancy will rise sharply. Cancer will cease to be a fatal problem.

10. NASA’s James Webb Space Telescope will be launched, which will help discover hundreds of new earth-like planets and partially learn the chemical composition of their atmospheres.

11. Rapid development of the multi-billion dollar space tourism industry.

12. In the public domain there will be “sources” for printing clothes on a 3D printer. Tens of millions of workers from poor countries will be left without even this low-paying job.

13. If breast cancer is detected on time, the chance of cure will be 100%.

14. The United States will actively grow organs from stem cells from patients themselves. The donation will in fact be liquidated.

15. We will not find extraterrestrial life on Mars. We will probably find it on the moons of Jupiter or Saturn.

16. SpaceX regularly brings people into lunar orbit in preparation for a manned mission to Mars.

17. Global warming will release the oldest viruses. The Chinese coronavirus will seem like a childish joke.

18. The Internet will completely replace television and print media.

19. Tesla cars will become the world’s best-selling cars.

20. Mass DNA editing experiments will begin. Thanks to this, children will be born with “built-in” protection against a huge number of diseases.

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Science & Technology

Designer has created a concept for the electric bike of the future

Futuristic motorcycles have become part of popular culture, associated with the concepts of the near future. They appeared in the film ” Tron: Legacy”, the anime “Akira” and in many video games from the “cyberpunk” genre. Recently, Russian designer Roman Dolzhenko presented his version of the bike of the future.

Russian designer has created a concept for the electric bike of the futureromorwise.com

MIMIC eBike – the concept of an electric superbike – originally existed as a sketch on a paper napkin. Later, the designer made the idea more realistic by rendering in 3DS max.

Minimalism prevails in motorcycle design. It lacks straight lines and protrusions. The dashboard of the bike is completely digital, and consists of a solid display showing basic information (speed and battery charge status).

Superbike MIMICromorwise.com

There are very few details about the superbike. Social network users are most often concerned about the question: how to turn the steering wheel with this design? The front wheel fairing and handlebar structure appear to be inactive. In an interview for InceptiveMind, Dolzhenko answered this question: the front of the motorcycle turns completely, but at a slight angle.

Superbike MIMICromorwise.com

There is no information on the cost of transport, capacity and production, which is not surprising. MIMIC eBike is just an extremely realistic concept art of the motorcycle of the future. Perhaps in a couple of years, some Elon Musk will adapt the MIMIC design for a real electric superbike.

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Science & Technology

Genes work differently in men and women

All of our cells have the same genes. They can have mutations, however, both in the muscle cell and in the neuron there is a gene for the globin protein, an insulin gene, an acetylcholinesterase gene, etc. But is it worth reminding that a muscle cell is not like a nerve cell? The point is that genes work differently in different cells.

… although these differences should not be exaggerated – even the end sections of chromosomes, which determine biological age, look the same in men and women.

More than ten years ago, a large international team of researchers launched the GTEx (Genotype-Tissue Expression) project, the goal of which was to determine the activity of all genes in all human tissues and organs. Samples of 49 tissues were taken from 838 donors – dead healthy people, mostly elderly. First of all, the DNA was read from each of the donors. Second, the amount of different RNA was analyzed in each tissue. As you know, genetic information from genes in DNA is first read into the messenger RNA (mRNA) molecule, and then proteins are already synthesized on the mRNA molecule (for simplicity, we are not talking about a large class of RNAs that do not encode proteins and which themselves perform various important functions in the cell). The more active a gene is, the more mRNA is read from it. Therefore, by the level of different mRNAs, one can understand where which genes are more active,

The activity of a gene depends on special regulatory sequences, which are also recorded in the DNA – that is, some sections of DNA affect others. By comparing the genetic text in DNA with the amount of different RNAs in different people, one can understand which regulatory regions in DNA affect a particular gene. Such regions (or loci) in DNA are called eQTL, expression quantitative trait loci, which can be roughly translated as loci that determine the level of activity.

As a result of the work, a whole bundle of fifteen articles was recently published in Science , Science Advances , Cell and other journals. Now, using the map of tissue genetic activity for each gene, you can check how it should work in a particular organ or part of it (because several samples were taken from each organ). On the other hand, by looking for a regulatory region (eQTL) in a person’s genome, one can estimate how certain genes will work. It’s genes – because each regulatory eQTL affects more than two genes.

Another important result concerns telomeres, the ends of chromosomes that shorten with each cell division. Telomeres are often used to assess biological age: the shorter they are, the older the body is. But usually blood cells are taken to measure telomeres. What if different fabrics age differently?

The researchers estimated the length of the end sections of chromosomes in 23 tissues, and came to the conclusion that blood does indeed provide an indication of age in general: telomeres in blood cells shorten in proportion to telomeres in other tissues. At the same time, earlier studies were not confirmed, in which female telomeres were on average longer than male ones – that is, neither women nor men have telomere advantages. Which is curious in its own way, since it is believed that women generally live longer than men . This is probably because telomeres are a significant, but not the only indicator of age. In addition, it was not possible to see a strong shortening of telomeres in smokers (here it is worth noting that lung cancer can occur without telomere shortening).

By the way, about women and men. Gender differences are hard to ignore, and we all know that men and women have different sex chromosomes and that men and women have different hormones. Obviously, this should affect the work of genes. Indeed, researchers have found that 37% of our genes work differently in men and women in at least one tissue. Moreover, some genes, relatively speaking, “work” only in one sex. For example, men with different DPYSL4 gene variants will have different body fat percentages. But in women, the DPYSL4 gene does not affect body fat – this does not mean that the gene does not work, just the amount of adipose tissue depends on other genes. Similarly, in men with different variants of the CLDN7 genethere will be different birth weights. In women, birth weight is linked to another gene, HKDC1 .

Many genes, whose activity depends on sex, are associated with diseases, but their “sex” differences were still unknown. Obviously, this information is useful in personalized therapy, when the patient is being treated according to his individual genetic characteristics. However, the authors of the work note that although a lot of “sex-dependent” genes were found, their activity itself does not change very much. In general, the gender genetic differences between men and women are not very large. We emphasize that this is precisely if we take it as a whole – because the genes on which, say, primary and secondary sexual characteristics depend, work in men and women in very different ways.

What else affects gene activity? For example, age – but here there is a gap in the received data. Above we said that the samples were taken mostly from people in years; in addition, more material is needed to analyze age differences across the entire genome. (By the way, it is possible that sex differences are manifested in different ways at different ages.) Some experts, according to The Scientist portal , generally strongly doubt the reliability of the results, because samples were taken from the dead, and not from living people. On the other hand, where can we find healthy volunteers who would allow them to take a piece of tissue from the bowels of their own brain? Subsequent studies are likely to greatly adjust this map of tissue gene activity, but, one way or another, the new data will have something to compare with.

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