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Author: Yana Nencheva, Biochemist, PhD candidate in Biophysics

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Imagine how the giraffe did not have a long neck and its neck was as short as a dog's. The giraffe and all the other short-necked animals ate the delicious low-lying leaves from the low branches of the low trees. One day, however, when numerous short-necked animal populations gathered, these trees began to disappear en masse. Only single, slightly taller trees of the species survived because the animals could not reach their highest branches. They had to support themselves on two legs to reach at least the lower ones, but they still did not reach the upper ones. So gradually the trees began to grow taller and taller. Some populations eating low-leafed species have disappeared in search of other habitats where the food is accessible.

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Coincidentally, one day a giraffe was born with a neck not as short, not as long as the current giraffes, but enough to reach the upper rows of leaves. So it grew stronger than the others and when it came time to breed - it was the most desirable giraffe. Thus, quite naturally, its genes were passed on to the future generations. Gradually, the giraffe's long neck evolved into a resistant gene because it gave it an evolutionary advantage.

Mutation-vs.-Natural-Selection

Mutation vs. Natural Selection

Mutation-vs.-Natural-Selection_0_0

Mutation-vs.-Natural-Selection_0_1

This story is an artistic example that aims to illustrate the importance of the interaction between populationsin order to obtain and retain a useful mutation . Yes, mutations should not be associated with negatives only. They are a major part of evolution, as they are the only source of brandnew "never-before-seen" genetic information. They are the culprit for the wonderful diversity that surrounds us.

Mutation-vs.-Natural-Selection_0_2

While mutations constantly create genetic diversity, the natural team "decides" which mutation is useful and which is not.

Mutation-vs.-Natural-Selection_0_3

<ol>
<li style="font-weight: 400;">Useful,as is the case with the trees and giraffe,</li>
<li style="font-weight: 400;">Harmful, as with numerous diseases, such as fatal family <a href="/p/kak_da_sie_spravim_s_biezsniieto_4a5e9367_3f8a_4aa7_bcf3_ecedac42f10c" target="_blank" rel="noreferrer">insomnia, for</a> example,</li>
<li style="font-weight: 400;">Indifferent, as in the case of a third nipple or the formation of additional skin, which binds tightly to each other two of the toes. These are mutations that do not give any evolutionary advantage, but at the same time do not preventthe individual from multiplying.</li>
</ol>

Mutation-vs.-Natural-Selection_0_4

If the mutation is not useful or indifferent, then natural selection eliminates it, making it difficult to transfer it to the next generation. For example, if the life time of the individual carrying the mutation is shortened, individual reproduction and transmission is sabotaged.

What-is-a-mutation-and-how-it-occurs

What is a mutation and how it occurs

What-is-a-mutation-and-how-it-occurs_1_0

What-is-a-mutation-and-how-it-occurs_1_1

A mutation is called any random change in the hereditary program that is not under the strict control of the cell. There are two types of mutations, depending on how much of the hereditary material affects:

What-is-a-mutation-and-how-it-occurs_1_2

<ol>
<li style="font-weight: 400;">Genetic - affect the sequence of nucleotides,</li>
<li style="font-weight: 400;">Chromosomal - somehow the structure of chromosomes is disturbed, or there is confusion in their number.</li>
</ol>

What-is-a-mutation-and-how-it-occurs_1_3

Mutations can occur spontaneously -a randomly born giraffe with a dingo neck - called thiswhen we don't have information on who the mutagenic factor is , which is a bit speculative and calls into question spontaneity.

What-is-a-mutation-and-how-it-occurs_1_4

The other type of mutations are induced - the mutagenic factor is known to them.It is used very often in laboratories for research with no effects harmful to the team ( the exception is spidermancases). It may be radiation radiation, biological mutagen, as well as a chemical of the most trivial type, such as mascara for eyelashes or nail polish with a carcinogen.

What-is-a-genetic/gene-mutation

What is a genetic/gene mutation

What-is-a-genetic/gene-mutation_2_0

What-is-a-genetic/gene-mutation_2_1

Gene mutations are the cause of molecular diseases, because damage in the nucleotide sequence leads to the synthesis of an abnormal product with impaired structure, Such aproduct is e.g. enzymes whose function, if disrupted, leads to changes in metabolism (enzymeopathies). There are over6,000 types of known enzymes, such as albinism. Another example is impaired action ofreceptors, which can lead to impaired function of specific hormones, nerve pathways, metabolites, etc.

What-is-a-genetic/gene-mutation_2_2

<h4>The gene mutation is a consequence of disrupting the sequence of <a href="/p/kak_nuklieinovitie_kisielini_dnk_i_rnk_dirizhirat_zhivota_7b8f007a_0254_40cb_8d72_36410852722e" target="_blank" rel="noreferrer">nucleotides</a> [ref. 1] in one way or another:</h4>

What-is-a-genetic/gene-mutation_2_3

<ul>
<li style="font-weight: 400;">Replacing one base in one nucleotide with another,</li>
<li style="font-weight: 400;">Insert one or more more bases,</li>
<li style="font-weight: 400;">Removal and loss of one or more bases,</li>
<li style="font-weight: 400;">Reverse an entire segment of DNA - imagine that the segment has bases in row "123456789" in the chain, but the mutation is to turn to "987654321",</li>
<li style="font-weight: 400;">Doubling a segment in the chain,</li>
<li style="font-weight: 400;">Translocation - moving a segment of DNA to another DNA molecule.</li>
</ul>

What-is-a-chromosomal-mutation

What is a chromosomal mutation

What-is-a-chromosomal-mutation_3_0

What-is-a-chromosomal-mutation_3_1

As its name shows , <a href="/p/kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noreferrer"></a> this is a mutation that occurs in chromosomes.

What-is-a-chromosomal-mutation_3_2

<h4>When there is a violation in the structure of the chromosome itself, this naturally leads to a violation in the DNA sequence, because from this the chromosome is built. There are four types of structural chromosomal mutations:</h4>

What-is-a-chromosomal-mutation_3_3

<ol>
<li style="font-weight: 400;">Doubling a section of the chromosome,</li>
<li style="font-weight: 400;">Removal and loss of a section of the chromosome,</li>
<li style="font-weight: 400;">Turning a section of the chromosome 180 degrees - sometime affects the <a href="/p/kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noreferrer">chromosome</a> centrifuge, other times not,</li>
<li style="font-weight: 400;">Translocation - a section of the chromosome is moved to another place in the same or another chromosome.</li>
</ol>

What-is-a-chromosomal-mutation_3_4

Whether it will be called a number chromosomal or genomic mutation is not particularlyrelevant.

What-is-a-chromosomal-mutation_3_5

<h4>Normally chromosomes are two in a homologous pair, but:</h4>

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<ul>
<li style="font-weight: 400;">if there is any additional chromosome, this is called trisomy,</li>
<li style="font-weight: 400;">if there is no one called monosomy</li>
</ul>

What-is-a-chromosomal-mutation_3_7

In both cases, the dynamics, the interaction between genes are disrupted, and this leads to strong deviations from the normal development of the individual.

What-is-a-chromosomal-mutation_3_8

<h4>Examples of such diseases are:</h4>

What-is-a-chromosomal-mutation_3_9

<ul>
<li style="font-weight: 400;">The incidence is 1 in 1,000 newborn girls and has a correlation with the age of the parents - if they are older, the probability of it happening is greater.</li>
<li style="font-weight: 400;">The syndrome "Supermen" has a frequency of 1.3 per 1,000 newborns and has two U chromosomes instead of one.</li>
<li style="font-weight: 400;">Down syndrome is perhaps the most common example of a mutation we are taught at school. <a href="https://www.bioseek.eu/en/eng/research/search?q=down%20syndrome&amp;p=1&amp;st=1&amp;tp=9&amp;f=4" target="_blank" rel="noopener"></a> </li>
<li style="font-weight: 400;"><a href="https://www.bioseek.eu/en/eng/research/search?q=Klinefelter%27s%20syndrome&amp;p=1&amp;st=1&amp;tp=9&amp;f=4" target="_blank" rel="noopener">Kleinfelter</a> syndrome is a consequence of a trisomy of the sexchromosome.</li>
</ul>

How-to-protect-ourselves-from-mutations

How to protect ourselves from mutations

How-to-protect-ourselves-from-mutations_4_0

How-to-protect-ourselves-from-mutations_4_1

After everything you've read so far, if you've been intimidated by the mutations, although they are due to the kind of diversity that surrounds us, it can always be a full genetic test [ref. 4]. It will give you the information that you are <a href="/p/ima_li_smisl_da_si_napravish_ghienietichien_tiest_0a6b928b_e726_4246_be6a_2ef32f93ccf0" target="_blank" rel="noreferrer">not carrying</a> somethinghidden, which is <a href="/p/iepighienietikata_ili_kak_nachint_na_zhivot_upravliava_ghienitie_ni_8ec805d0_069f_4823_89cd_c55d051a9610" target="_blank" rel="noreferrer"></a> fatal + the probability of it being unlocked.

How-to-protect-ourselves-from-mutations_4_2

Another option that has been very actively worked on in recent years is gene editing, which aims to correct a harmful mutation or just a stretch of DNA that a person does not like. Perhaps the last sentence sounds like science fiction, but there are already several genome editing approaches that have been developed. The most convenient and inexpensive approach for the moment is the <a href="/p/tiekhnologhiiata_crispr_cas9_ietichna_li_ie_i_mozhie_li_da_sie_izpolzva_za_liechieniie_eb882680_6ed6_4a9c_b5a8_840622af3e3b" target="_blank" rel="noreferrer">CRISPR-Cas9</a>system , which is expected to develop towards the prevention and treatment of a number of diseases [ref. 6].

Even-if-you-do-not-decide-to-take-a-genetic-test-and-observe-"epigenetic-therapy",-you-may-follow-some-simple-rules-in-your-daily-life-to-save-yourself-some-mutagenic-factors:

Even if you do not decide to take a genetic test and observe "epigenetic therapy", you may follow some simple rules in your daily life to save yourself some mutagenic factors:

Even-if-you-do-not-decide-to-take-a-genetic-test-and-observe-"epigenetic-therapy",-you-may-follow-some-simple-rules-in-your-daily-life-to-save-yourself-some-mutagenic-factors:_4_0

<ul>
<li style="font-weight: 400;">Minimize complex chemical preparations for cleaning the home, because they contain several irritating mucous membranes of the nose and lungs compounds. Use mask, gloves and open windows. This may be a recommendation on the topic of allergies, but these are also mutagenic factors that should not be overlooked;</li>
<li style="font-weight: 400;">Minimize the use of parabens (paraben) and methylchloroisothiazolinone, because studies indicateprerequisites for carcinogenicity;</li>
<li style="font-weight: 400;">When cleaning your nails with a nail polish remover- do it on the terrace orin another ventilated place - often it contains formaldehyde, formaleline, which is a carcinogen;</li>
<li style="font-weight: 400;">Make sure that the composition of the lipsticks does not have the presence of bottled hydroxyanisole (butylated hydroxyanisole, BHA) and bottled hydroxytoluene (butylated hydroxytoluene, BHT). These ingredients have shown carcinogenic properties in studies with laboratory animals [ref. 6];</li>
<li style="font-weight: 400;">It may sound trivial, but reduce stress, because itincreases adrenaline and this affects the levels of hormones in general that dictate normal functioning;</li>
<li style="font-weight: 400;">Last but not least, the most underestimated factors are clean food and fruitful rest , whichrestore thebody.</li>
</ul>

<ol><li style="font-weight: 400;"><a href="kak_nuklieinovitie_kisielini_dnk_i_rnk_dirizhirat_zhivota_7b8f007a_0254_40cb_8d72_36410852722e" target="_blank" rel="noopener">How nucleic acids DNA and RNA orchestrate life</a></li><li style="font-weight: 400;"><a href="kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noopener">How genes determine resemblance to our parents</a></li><li style="font-weight: 400;"><a href="http://www.mayamarkov.com/biology/17Mutations1/17Mutations1.htm" target="_blank" rel="noopener">Mutations. Gene mutations. Action of genes</a></li><li style="font-weight: 400;"><a href="ima_li_smisl_da_si_napravish_ghienietichien_tiest_0a6b928b_e726_4246_be6a_2ef32f93ccf0" target="_blank" rel="noopener">Does it make sense to take a genetic test?</a></li><li style="font-weight: 400;"><a href="iepighienietikata_ili_kak_nachint_na_zhivot_upravliava_ghienitie_ni_8ec805d0_069f_4823_89cd_c55d051a9610" target="_blank" rel="noopener">Epigenetics or how lifestyle governs our genes</a></li><li style="font-weight: 400;"><a href="tiekhnologhiiata_crispr_cas9_ietichna_li_ie_i_mozhie_li_da_sie_izpolzva_za_liechieniie_eb882680_6ed6_4a9c_b5a8_840622af3e3b" target="_blank" rel="noopener">CRISPR-Cas9 technology - is it ethical and can it be used to treat</a></li><li style="font-weight: 400;"><a href="7_stpki_v_izbora_na_kachiestviena_kozmietika_2b839f29_de72_4e6a_9285_13b57cc8d17a" target="_blank" rel="noopener">8+1 steps in choosing quality cosmetics</a></li></ol>

<a href="kak_nuklieinovitie_kisielini_dnk_i_rnk_dirizhirat_zhivota_7b8f007a_0254_40cb_8d72_36410852722e" target="_blank" rel="noopener">How nucleic acids DNA and RNA orchestrate life</a>

<a href="kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noopener">How genes determine resemblance to our parents</a>

<a href="http://www.mayamarkov.com/biology/17Mutations1/17Mutations1.htm" target="_blank" rel="noopener">Mutations. Gene mutations. Action of genes</a>

<a href="ima_li_smisl_da_si_napravish_ghienietichien_tiest_0a6b928b_e726_4246_be6a_2ef32f93ccf0" target="_blank" rel="noopener">Does it make sense to take a genetic test?</a>

<a href="iepighienietikata_ili_kak_nachint_na_zhivot_upravliava_ghienitie_ni_8ec805d0_069f_4823_89cd_c55d051a9610" target="_blank" rel="noopener">Epigenetics or how lifestyle governs our genes</a>

<a href="tiekhnologhiiata_crispr_cas9_ietichna_li_ie_i_mozhie_li_da_sie_izpolzva_za_liechieniie_eb882680_6ed6_4a9c_b5a8_840622af3e3b" target="_blank" rel="noopener">CRISPR-Cas9 technology - is it ethical and can it be used to treat</a>

<a href="7_stpki_v_izbora_na_kachiestviena_kozmietika_2b839f29_de72_4e6a_9285_13b57cc8d17a" target="_blank" rel="noopener">8+1 steps in choosing quality cosmetics</a>

Mutations vs. Natural Selection

https://d20hztklr4qnvi.cloudfront.net/de935967-7301-46ee-b707-4fe4e7dfac03_middle.jpg

 Mutations vs. Natural Selection

Yana Nencheva

Author: Rositsa Tashkova, Master of Molecular Biology and Microbiology

Are we getting closer to the sci-fi scenario for designer babies - will we be able to eliminate genetic <a href="/p/mutatsii_srieshchu_iestiestvien_podbor_e4a316a0_b5fd_4a51_8dc0_12a14405f8f2" target="_blank" rel="noreferrer">mutations</a> from their root, and is it ethical to interfere to such an extent in the emergence and shaping of life - considered a miracle so far?

The discovery of CRISPR-Cas9 gene editing technology raises all these and other questions.

Gene-editing---fantasy-or-reality

Gene editing - fantasy or reality

Gene-editing---fantasy-or-reality_0_0

Genome editing (also called geneediting) <a href="/p/kak_nuklieinovitie_kisielini_dnk_i_rnk_dirizhirat_zhivota_7b8f007a_0254_40cb_8d72_36410852722e" target="_blank" rel="noreferrer"></a> is a group of <a href="/p/kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noreferrer">technologies</a> that enable scientists to change the body's DNA.

Gene-editing---fantasy-or-reality_0_1

Several genome editing approaches have been developed. The CRISPR-Cas9 system (since 2009) has recently become known, which has generated a lot of excitement in the scientific community because itis faster, cheaper, more accurate and more effective than other existing gene editing methods.

Gene-editing---fantasy-or-reality_0_2

Genome editing is of great interest in the prevention and treatment of human diseases. At present, most studies in this regard are done in order to understand the mechanisms of various diseases using cells and animal models.

Gene-editing---fantasy-or-reality_0_3

Gene-editing---fantasy-or-reality_0_4

To do this, scientists edit the genomesof animals <a href="/p/kak_ghienitie_opriedieliat_prilikata_s_roditielitie_ni_2256bb0a_9ee8_4d00_8f3e_7ca44b90aa45" target="_blank" rel="noreferrer"></a>, <a href="https://www.bioseek.eu/bg/eng/research/pubmed/Genome_engineering_using_the_CRISPR_Cas9_system_24157548" target="_blank" rel="noopener"></a> such as mice and zebra fish [ref. 11]because animals and humans have many commongenes. For example, mice and humans share about 85% of their genes! By changing a gene or multiple genes into a mouse, researchers can observe how these changes affect mouse health and suggest how such changes in the human genome can affect our health.

Gene-editing---fantasy-or-reality_0_5

Scientists are still trying to find out if this approach is safe and effective for use in humans. It is used in research into a wide <a href="/p/cancer" target="_blank" rel="noreferrer"></a> <a href="/p/psychiatry_and_psychology" target="_blank" rel="noreferrer"></a> variety of diseases , including cystic fibrosis, haemophiliaand sickle cell anaemia.

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works

What's behind the CRISPR-Cas9 abbreviation and how it works

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works_1_0

CRISPR-Cas9 technology is based <a href="/p/kakva_ie_razlikata_miezhdu_baktieriia_i_virus_i_kakvo_tochno_ie_klietkata_f496ccd4_1ffa_42b5_bd7a_73a56893200d" target="_blank" rel="noreferrer"></a>on a gene editing system that is naturally found in bacteria.

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works_1_1

CRISPR arrays allow bacteria to "remember"viruses . If viruses attackagain, bacteria produce RNA segments of <a href="/p/kak_nuklieinovitie_kisielini_dnk_i_rnk_dirizhirat_zhivota_7b8f007a_0254_40cb_8d72_36410852722e" target="_blank" rel="noreferrer">CRISPR</a>arrays that recognize and target the corresponding DNA sequencesof viruses. The bacteria then useCas9 or another similar enzyme to cutdna, which disables the virus. It can be said that it is the immune system of bacteria.

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works_1_2

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works_1_3

The CRISPR-Cas9 system works in a similar way in the laboratory. Researchers created a small piece of RNA with a short sequence, acting as a "guide", which attaches to a certain target sequence of DNA in the genome. RNA is also associated with the Enzyme Cas9. [<a href="https://www.bioseek.eu/bg/eng/research/pubmed/Genome_engineering_using_the_CRISPR_Cas9_system_24157548" target="_blank" rel="noopener">ref. 10</a>]

What's-behind-the-CRISPR-Cas9-abbreviation-and-how-it-works_1_4

As with bacteria, modified RNA is used to recognize DNA sequence, and the Cas9 enzyme cuts DNA at the target site.

CRISPR-Cas9-system-applications

CRISPR-Cas9 system applications

CRISPR-Cas9-system-applications_2_0

The technology has been used for functional inactivation of genes in human cell lines and cells (in laboratory conditions), for the study of the Candida albicans fungus, for modifying yeastsusedfor the production of biofuels and genetically modifying crops. [<a href="https://www.nature.com/news/crispr-the-disruptor-1.17673" target="_blank" rel="noopener">ref. 1</a>] CRISPR can also be used to modify mosquitoesso that they cannot transmitdiseases such as malaria [<a href="https://www.nature.com/articles/nbt.3473" target="_blank" rel="noopener">ref. 2</a>].

CRISPR-Cas9-system-applications_2_1

CRISPR-Cas9 can also be used as a diagnostictool. Instead of the Cas9 enzyme, another similar enzyme can beused, such as Cas13, which, in addition to cutting the target area of DNA, also begins to cut RNAindiscriminately , which can be used for signaling in diagnostic tests.

CRISPR-Cas9-system-applications_2_2

CRISPR-Cas9-system-applications_2_3

For example, in 2018, the SHERLOCK test was established, to which molecules of RNA have been added, which signal when cut by Cas13.

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment

CRISPR as gene therapy and can it be used as a treatment

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment_3_0

Scientists are developing gene therapies (treatments including gene editing) to prevent and treat diseases inhumans.

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment_3_1

There are two different categories of gene therapies: germ therapy and somatic therapy.

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment_3_2

Germ line therapies alter DNA in reproductive cells (sperm and eggs). Changes in the DNA of reproductive cells are passed down from generation to generation.

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment_3_3

Somatic therapies, on the other hand, are aimed at non-reproductive cells, and the changes made in these cells affect only theperson who receives gene therapy, that is. not passed on to his generation.

CRISPR-as-gene-therapy-and-can-it-be-used-as-a-treatment_3_4

Successful-cases-of-gene-therapy-and-CRISPR-treatment

Successful cases of gene therapy and CRISPR treatment

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_0

In 2015, scientists in the UK successfully used somatic gene therapy to treat a little girl namedLayla. [<a href="https://www.genome.gov/about-genomics/policy-issues/what-is-Genome-Editing" target="_blank" rel="noopener">ref. 4</a>]

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_1

In the end, this therapy saved Leila's life. However, this type of treatment is still experimental , as there are many technical barriers and ethical problems associated with genomeediting.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_2

It was recently reported that two people with beta <a href="/p/vidovie_talasiemiia_simptomi_i_liechieniie_afa4d9df_f99e_4122_bba7_329dd33442e4" target="_blank" rel="noreferrer">thalassaemia</a> and one with sickle cell anemia no longer need a blood transfusion after their own stem cells from their bone marrow were genetically edited with CRISPR. [<a href="https://www.npr.org/sections/health-shots/2020/06/23/877543610/a-year-in-1st-patient-to-get-gene-editing-for-sickle-cell-disease-is-thriving" target="_blank" rel="noopener">ref. 5</a>]

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_3

These are the first patients officially reported to have undergone CRISPR gene therapy.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_4

Beta thalassaemia and sickle cell anemia are conditions caused by mutations that affect hemoglobin - the protein that <a href="/p/kakva_ie_razlikata_miezhdu_bieltk_i_protiein_b1b6b96e_e340_46d2_9768_ac9fa8cd6adc" target="_blank" rel="noreferrer"></a>carries oxygen in red bloodcells. Patients with severe forms of disease require regular blood transfusions.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_5

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_6

Types of thalassaemia, symptoms and treatment

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_7

There are a very small numberof people who carry themutations for these diseases, but do nothave any symptoms , because inadulthood they continue to produce fetal hemoglobin.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_8

In thisstudy, stem cells from patients' bone marrow were extracted and the gene that excluded fetal hemoglobin production was deactivated by CRISPR.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_9

The remaining <a href="/p/transplantatsiiata_na_stvolovi_klietki_kato_liechieniie_na_rak_a70ce10f_6768_4669_b459_146e0786d1cd" target="_blank" rel="noreferrer"></a>cells of the bone marrow are killed by chemotherapy , then replaced with edited cells. This is done to ensure that new blood cells are produced by edited stemcells, but chemotherapy can have serious side effects.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_10

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_11

The first two patients with beta thalassaemia no longer need a blood transfusion. They were subjected to gene therapy 15 months ago and 5months ago. [<a href="https://www.newscientist.com/article/2246020-three-people-with-inherited-diseases-successfully-treated-with-crispr/" target="_blank" rel="noopener">ref. 6</a>]

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_12

The three patients experience some adverse effects from chemotherapy, but editing the gene through CRISPR currently seems safe.However, patients will be monitored for the rest of their lives.

Successful-cases-of-gene-therapy-and-CRISPR-treatment_4_13

Technical-barriers-to-the-use-of-the-technology

Technical barriers to the use of the technology

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Although CRISPR technology is better than older gene editing technologies, it is not perfect. Sometimes shears happen in the wrongplace . Scientists are still not sure how theseerrors can affect patients.

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Assessing the safety of gene therapies and improving gene editing technologies are critical steps toensure that they can be appliedto patients.

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But CRISPR's ability to safely edit genes in human embryos has been called into question after several recent reports describing huge damage to the DNA ofembryos undergoing editing.

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The experiments described in each of the three reports published as reprints on the bioRxiv server aimed to edit only one gene. But the results show large-scale, unforeseen stretches of DNA that have been erased or rearranged in the areas around the target sequence.

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While previous research has shown that genetic editing can lead to mutations away from the target region, these new studies draw attention tomore localized damage - including larger SEQUENCES of DNA that could be overlooked by traditional safety screenings.

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These studies were intended for research purposesonly , meaning that the embryos were destroyed after the experiment was completed. But in response to their findings, many researchers have expressed their objections to continuing experiments with embryo editing. [<a href="https://www.the-scientist.com/news-opinion/crispr-gene-editing-prompts-chaos-in-dna-of-human-embryos-67668" target="_blank" rel="noopener">ref. 12</a>]

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Is it ethical to interfere with our own nature

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In the first place, genome editing should be safe before it can be used totreat patients.

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Most of the changes in gene editing are limited to somatic cells and affect only certain tissues, not being transmitted from one generation to another. [<a href="https://ghr.nlm.nih.gov/primer/genomicresearch/genomeediting" target="_blank" rel="noopener">ref. 9</a>]

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Editing the sex cells and the genome of the embryo poses a number of ethical challenges, including whether it would be permissible to use this technology to improve human traits such as height orintelligence.

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In 2018 Chinese scientist He Jiankui reported that he performed gene editing in 2 embryos, The children's father is HIV-positive, and He Jiangwei used CRISPR to introduce changes in the genome of the embryos to make them resistant to the virus (a small number of people are inherently resistant to HIV infection because they have a mutation in the receptor that the virus binds to infect <a href="/p/mutatsii_srieshchu_iestiestvien_podbor_e4a316a0_b5fd_4a51_8dc0_12a14405f8f2" target="_blank" rel="noreferrer"></a> cells).

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The incident has sparked intense resentment in the scientific community, with many scientists calling for a moratorium on the use of the technique in human embryos because they believe it is unethical and it is too early to take such steps.

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He Jiankwei has now been sentenced to three years in prison and a $430,000 fine. [<a href="https://www.scientificamerican.com/article/crispr-babies-scientist-sentenced-to-3-years-in-prison/" target="_blank" rel="noopener">ref. 7</a>]

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Currently, nothing is known about the condition and health of babies. There is evidence that editing has not only failed - some babies' cells carried the mutant gene, others have not, but perhaps editing has led to other unwanted mutations- which could prove detrimental to children's lives in the future. [<a href="https://www.theverge.com/2018/11/29/18116830/crispr-baby-he-jiankui-genetics-ethics-science-health-mutation" target="_blank" rel="noopener">ref. 8</a>]

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Some other ethical questionsthat scientists andsociety should consider are:

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<ul>
<li style="font-weight: 400;">Is it ok to use gene therapy on an embryo when it is impossible to obtain permission from the embryo for treatment? Is getting permission from parents enough?</li>
<li style="font-weight: 400;">What happens if gene therapies are too expensive and only wealthy people can access and afford them? </li>
<li style="font-weight: 400;">Will some people use gene editing for traits that aren't important for health, such as athletic ability or stature?</li>
</ul>

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Most people agree that scientists do not currently have to edit the genomes of germ cells. Many countries and organizations have strict regulations to prevent germ line editing for the reasons listed above. Only the future will show whether CRISPR will spark a revolution in medicine or be dismissed as unreliable and unethical technology.

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