Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Is the test - tube conception dangerous?

20.11.2007
The number of “infants from a test-tube” is growing year by year, and in highly developed countries it will soon make 1% to 3% of all new-borns.

But how safe are the auxiliary reproductive technologies (ART)? Having summarized the data accumulated by the world science, specialists of the Research Institute of Medical Genetics (Tomsk Scientific Center, Siberian Branch, Russian Academy of Medical Sciences) tried to look into only one aspect of the ART safety – risk of genomic imprinting diseases.

What kind of diseases are they? Normal mammal development requires that maternal and paternal gene sets differed functionally. In certain genes, only the maternal copy should work. And in others – only the paternal copy should. The mechanism regulating functional differences of parental genomes is called genomic imprinting. This is a complicated and multi-step process, which starts in the parental gametal cells, where special enzymes mark and disconnect the required genes (a human being has about 70 of them), and continues after impregnation. Heavy pathologies can be caused by failure of such marking at some stage, and several genomic imprinting diseases are known with human beings.

Genomic imprinting reacts to external factors, and the researchers expected that the auxiliary reproductive technologies could influence it. The first example of such influence was discovered in experiments on animals’ artificial impregnation. The “large posterity syndrome” sometimes develops with big horned cattle and sheep after embryo cultivation, the posterity weight often by twice exceeding the norm. Another important indication is increased fetus mortality in the course of pregnancy and in labour, at that the pregnancy is long and the delivery is difficult. The deceased fetus and new-borns have internal pathologies. The “large posterity syndrome” caused by derangements of genomic imprinting is very similar on the surface to the Wideman-Beckwith human syndrome arising for the same reason. In case of the Wideman-Beckwith syndrome, infants are born very big and with multiple pathologies. The syndrome frequency is normally one case per 12 to 15 thousand of new-borns, but it is several times higher with the children born with the help of the ART.

The researchers suggest several hypotheses explaining why genomic imprinting diseases occur more often in case of the ART than in case of traditional conception. Firstly, the process may be influenced by methodical peculiarities of artificial impregnation. In case of extracorporal fertilization, women are injected hormones to stimulate the ovulation. Possibly, gonadotropins accelerate maturation of ovums, which have not finished yet the genomic imprinting process. In some cases ovums have to be cultivated in nutrient medium prior to fertilization, and after fertilization embryos are bred on it before transplanting in the maternal organism. The nutrient medium composition and the lack of signals coming from the maternal organism in a normal case can also impact genomic imprinting, which takes place both in maturing ovums and in the developing embryo. It is not improbable that the genome marking can be influenced by cryopreservation of gametal cells and embryos, which is often practiced.

Secondly, the ART enables the events that would have never happen in a natural way. Thus, “anomalous” ovums can mature in case of hormone stimulation, such ovums would have scarcely mature during a natural cycle. Spermatozoa also can have imprinting defects. Normally, their fertility is low but they can be used for artificial impregnation, and then trouble is inevitable. Finally, artificial impregnation makes it possible that ill children are born with infertile married couples who have predisposition to genomic imprinting diseases.

Now, there is no unanimous opinion among the researchers as regards to the ART and genomic imprinting diseases. Some assume that the birth “the test-tube” children is an extremely rare event and it cannot be the reason for rejection of artificial impregnation. Their opponents believe that the genomic imprinting abnormalities cases known to us make only the visible part of the iceberg. We do not know too many things, and the risk of giving birth to infants with imprinting defects is although little, but important. Therefore, it is necessary to investigate the problem and to make extracorporal fertilization safe in every respect.

Nadezda Markina | alfa
Further information:
http://www.informnauka.ru

More articles from Health and Medicine:

nachricht Ayahuasca compound changes brainwaves to vivid 'waking-dream' state
19.11.2019 | Imperial College London

nachricht A step closer to cancer precision medicine
15.11.2019 | University of Helsinki

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Atoms don't like jumping rope

Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.

By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...

Im Focus: Images from NJIT's big bear solar observatory peel away layers of a stellar mystery

An international team of scientists, including three researchers from New Jersey Institute of Technology (NJIT), has shed new light on one of the central mysteries of solar physics: how energy from the Sun is transferred to the star's upper atmosphere, heating it to 1 million degrees Fahrenheit and higher in some regions, temperatures that are vastly hotter than the Sun's surface.

With new images from NJIT's Big Bear Solar Observatory (BBSO), the researchers have revealed in groundbreaking, granular detail what appears to be a likely...

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

Im Focus: New Pitt research finds carbon nanotubes show a love/hate relationship with water

Carbon nanotubes (CNTs) are valuable for a wide variety of applications. Made of graphene sheets rolled into tubes 10,000 times smaller than a human hair, CNTs have an exceptional strength-to-mass ratio and excellent thermal and electrical properties. These features make them ideal for a range of applications, including supercapacitors, interconnects, adhesives, particle trapping and structural color.

New research reveals even more potential for CNTs: as a coating, they can both repel and hold water in place, a useful property for applications like printing,...

Im Focus: Magnets for the second dimension

If you've ever tried to put several really strong, small cube magnets right next to each other on a magnetic board, you'll know that you just can't do it. What happens is that the magnets always arrange themselves in a column sticking out vertically from the magnetic board. Moreover, it's almost impossible to join several rows of these magnets together to form a flat surface. That's because magnets are dipolar. Equal poles repel each other, with the north pole of one magnet always attaching itself to the south pole of another and vice versa. This explains why they form a column with all the magnets aligned the same way.

Now, scientists at ETH Zurich have managed to create magnetic building blocks in the shape of cubes that - for the first time ever - can be joined together to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

Structure of a mitochondrial ATP synthase

19.11.2019 | Life Sciences

The measurements of the expansion of the universe don't add up

19.11.2019 | Physics and Astronomy

Ayahuasca compound changes brainwaves to vivid 'waking-dream' state

19.11.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>