Genes Prevent The Inheritance Of Cystic Fibrosis Biology Essay

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I am very strongly considering a career in the medical field after high school and I do believe that genetic modification may be the future of medicine. In general people in modern society are highly uneducated about genetic modification. We are presented with genetic modification almost every day, particularly in the food that we actually consume. Inheritable genetic modification takes this topic a step further in that it investigates the effects on genetic modification on humans. As health science technology becomes more advanced I am a strong believer in that prevention is better than cure and thus am interested in the success rate of this type of experimentation. I have chosen cystic fibrosis as the disease of the basis of my research as it follows the criteria of genetic inheritance as a cause.


I will gather facts and background information on my research topic through the internet as a primary source. I will also be researching the same information from books and scientific journals.



Gene therapy or genetic engineering for therapeutic purposes has always been a very controversial and widely discussed treatment that holds great possibility, but also great danger. The field of genetic engineering with regards only to genetically inherited diseases is, although reduced; still a very wide field and therefore I have narrowed my research down to investigating only whether Cystic Fibrosis can be prevented in offspring by means of inheritable genetic modification.

2.1. - What is cystic fibrosis?

[4] Cystic Fibrosis is a genetically inherited disease caused by a defective gene called the cystic fibrosis transmembrane conductance regulator (CFTR). This gene is found in and effects the correct functioning of the epithelial cells in the body. These cells form one of the major mammalian tissue groups and are mainly found in glands such as the sweat glands of the skin and as lining in the passageways and cavities of the body including the liver, pancreas, lungs, esophagus, reproductive system and digestive tract. A main function of these epithelial cells is to produce mucus, which is a slimy substance that lines the areas where these cells are found. This mucus serves as protection against bacterial or fungal infections and also protects the lining of the stomach from being digested by the strong stomach acid.

The faulty CFTR gene leads to the epithelial cells being unable to regulate sodium (salts) and fluid properly in the body and this leads to mucus becoming thick and sticky. This thick, sticky mucus is the main cause of most cystic fibrosis symptoms. Serious infections arise in the lungs because this thick mucus that has trapped harmful bacteria is much more difficult the pass out of the body. A build-up of mucus in the pancreas can also prohibit certain digestive enzymes from reaching the intestine and this inhibits the body's ability to absorb nutrients and can also lead to very severe constipation. The imbalance of salts in the body can lead to very salty sweat which creates a mineral imbalance in the body that can cause low blood pressure, dehydration or heat strokes. Cystic fibrosis sufferers often die from respiratory failure, pulmonary infection or multiple organ failure.

Cystic Fibrosis is an autosomal recessive disorder. This means that for a person to be a sufferer of cystic fibrosis they will have to inherit the defective CFTR gene from both parents. It is possible that both parents are simply carriers of the faulty gene. Therefore each parent has only one defective CFTR gene and as a result they do not display cystic fibrosis symptoms, but their children could still inherit the disease.

2.2. - Cystic fibrosis Statistics:

[3]Statistic show that approximately 700 people in South Africa are currently living with cystic fibrosis. The disease is prevalent in people that are of European descent as opposed to people who are of African descent. One in 3000 babies in America and one in 2500 babies in the Uk are being born with cystic fibrosis every year. The chances of a person having cystic fibrosis is also much higher as the disease can result from more than 1000 different mutations of genes. None of the statistics of people living with cystic fibrosis can be taken as completely accurate. This is because the disease is not very well known and symptoms are often passed off as a result of different conditions, therefore there is a large portion of people unknowingly living with cystic fibrosis. The life expectancy for sufferers has increased by substantially over the last 30 years, where patients used to die in childhood, the average life expectancy is now around 37 if the person receives treatment, but a person may live much longer.

2.3. - Inheritable Genetic Modification:

The following points are some of which were underlined in the scientific report: [5] Human Inheritable Genetic Modifications, by Mark S. Frankel and Audrey R. Chapman (2000). Inheritable Genetic Modification (IGM) is a recently developed type of genetic engineering that involves altering the genetic make-up of an organism, but these alterations would occur in the gametes (a spermatozoa or ovum) or in the early embryo. The organism would then continue to develop and adopt these altered genes. Not only will that organism develop with the recombinant DNA, but this DNA will also be passed on to any offspring that the organism may have. There have been quite a few studies that deal with the treatment of patients with genetic disorders, but these have all targeted the somatic cells of the individual which means that this specific gene therapy will not help future generations, but only the organism concerned.

2.4. - Pros and Cons of IGM:

This type of genetic treatment obviously comes with multiple advantages, the main one being that it has the possibility to eradicate inherited diseases from families completely as opposed to simply using somatic gene therapy every generation. It also allows couples with certain inherited diseases or syndromes to ensure that their offspring do not suffer from the same condition.

Unfortunately a number of issues also arrive with this treatment IGM has therefore not yet been trialed on humans. This report raises the issue that we are unable to know when it will be safe to use such a treatment on humans. IGM involves the dangerous procedure of inserting foreign genetic material into the DNA of a human rather than simply replacing or correcting genetic material. It is thus impossible to be sure of the safety and success of such a procedure without having testing it in animals and humans over several generations.

On top of the fact that it may not be medically safe for a long time, IGM also presents ethical and religious issues. There is inevitably the possibility that IGM will be used to "enhance" children so that they are more intelligent, athletic, and attractive or have any other desirable qualities. Not only can this be seen as ethically incorrect, but it could also create an enormous separation of the classes in the sense that upper class societies will be able to afford IGM treatment.

Drawing from a different source, the scientific article [1] Somatic and Germline Gene Therapy by Sherman Elias and George J. Annas, clearly categorises the cons of IGM into three points.

" Potential clinical risks": this mainly involves the risks that the insertion of new genetic material could ultimately affect or mutate the existing functional DNA, thereby making conditions of possible offspring even worse or most drastically resulting in the loss of gametes or embryos.

"Changing the Gene Pool": here the con presented is that we will permanently alter the human genome and in doing so, that we will interfere with evolution. The article suggests that what we may see as a disease today, could eventually end up being an important quality and by removing these characteristic we could be doing irreversible damage to the human gene pool and well as taking away from its value and our own "heritage".

"Social Dangers": the risk involved here is similar to the ones mentioned above and brings in religion in that we might be able to "enhance" the genome of a human being to possess certain desirable qualities. This may also create a massive divide between societal classes as some will be able to afford treatment and some not.

The pros of IGM are then divided into two points:

"Efficiency": this is based of prevention as opposed to cure. Assuming that there is proficient treatment for a disease, instead of having to receive somatic cell therapy generation after generation, IGM would simply rid one's genome of an inheritable disease.

"Unique Diseases": in this case IGM would be justified in diseases where somatic gene therapy has failed to provide any relief from the disease.

Although this source proved very insightful, it seemed slightly biased against IGM.

Referring back to the scientific report: [5] Human Inheritable Genetic Modifications, finally there is commentary of the "therapeutic need" for IGM. Although it is clear to see that a halt to genetically inherited diseases should be the main reason to pursue with experimentation of IGM, the report recognises that this is actually not very necessary. For people who are already suffering from the inherited diseases, there is treatment such as the somatic gene therapy mentioned above. Not only this, but there are also many methods that couples can use to avoid having children with their inherited diseases such as "preimplantation diagnosis and embryo selection". These suggest that there is not a great need for the further experimentation in the field of IGM for inherited diseases such as cystic fibrosis.

This scientific essay: [2] Protecting the Endangered Human, by George J. Annas, Lori B. Andrews and Rosario M. Isasi (2002), shares a similar, yet much more dramatic view on the topic of IGM as the previous source. It goes as far as to describe IGM as a possible "[weapon] of mass destruction". Although the source recognises the same possible benefits of perfecting such a treatment, it feels that the possible risks far outweigh these benefits. Fears are laid out about the probable creation of a superhuman race when IGM procedures develop to a point where scientists are able to construct and select certain elements of the human genotype. Not only does the source express a strong fear for the human race, but it also calls for urgent international consensus to construct laws that will prohibit the use of any such IGM procedures.

2.5. - Evidence of IGM in Animals:

The scientific article,[7] Mario's Transgenic Technology (2012), describes one of the first successful IGM experimentations that was carried out on mice. This experiment was essentially the reverse of the therapeutic intentions of IGM, but it carries the same principles. The study was to see the contribution that a certain gene had to panic attacks. The mutated gene, along with a "drug resistance marker gene" was entered into the embryonic stem cells of a brown mouse. Thereafter a certain drug is added that kills the cells without the "drug resistance marker gene" and therefore only embryos with the mutated gene remain. In this way scientists were then able to enter any gene into the mouse genome. Some of these stem cells would develop into reproductive cells and when bred with other transgenic mice, scientists were able to study the effects of many different mutated genes that are commonly found in humans. Although the human genome is much more complex, it is most definitely a viable stepping stone to IGm in humans.

2.6. - Somatic Gene Therapy:

Although there has been no experimentation with regards to cystic fibrosis, or even humans, using IGM, there has most definitely been experimentation in somatic cell gene therapy. On the website [9] Wales Gene Park (2011), somatic gene therapy is described as a process whereby correct genes are inserted into the body, usually via a retrovirus as a vector, of a patient with a genetic disease so that the mutated genes or alleles can be replaced with functional ones. These "corrected" cells will then go on to divide and hopefully the number of cells with the harmful mutated gene will decrease substantially. In comparison to germline gene therapy, it is seen us much less controversial as not only does it affect just the person receiving the treatment and not their future offspring, but it had also been tested on humans in many occasions and has been proved highly successful in several cases.

There have been several trials in somatic gene therapy with regards to cystic fibrosis specifically. [6] The Learn Genetics website of the University of Utah (2012) stated that experimentation of this treatment began in 1993. At this stage the adenovirus, a virus that causes respiratory infections in humans, was used as a vector for the transfer of the normal CFTR gene into the somatic cells of the body. Initially the trial appeared successful, but further experimentation showed that the levels of CFTR were too low. Scientists speculated that doses were too low and that the virus could not easily enter the air passages, but upon administering higher dosages, an immune response to the adenovirus was triggered in the bodies of the patients.

Following trials in 1995 commenced by using liposome (a spherical particle of a water droplet enclosed by a lipid-bilayer), but this was not successful as not only did the CFTR not last very long, but patients experienced side-effects such as fever and inflammation. Seemingly the most recent trial in 1998 showed promising results through the use of a "adeno-associated virus" that showed no negative side-effects. Although it seems that a final, established treatment has not yet been developed, scientists are hopeful that they are now getting much closer to a treatment.

2.7. - Alternative Methods to Preventing Genetic Diseases:

[7] With current medicinal technology, somatic or germline gene therapy are most definitely not the only choices that prospective parents have in ensuring that their offspring do not inherit genetic diseases. Some of the following are viable alternative options:


This is a technique is used in in vitro fertilization methods whereby the genome of an embryo is tested for any mutations before it is implanted into the uterus of a female. In this way females could, in a sense, prevent a pregnancy in which their unborn shild has a genetic disease.


Similar to preimplantation diagnosis, this method is one in which several embryos develop in vitro and are genetically tested. After a genetic analysis on the embryos, the prospective parents can then ultimately select which embryo they want to use to implant in the uterus of the female and continue the pregnancy.


Prior to pregnancy, this will provide parents with a very good idea of the chances they have of carrying a genetic disease onto an offspring. One must hand in extensive family medical history and can undergo specific genetic tests to determine whether it is like that there will be a mutation on the genome of their offspring. Here, parents can also get advice on alternative treatment, care, support or information on specific genetic diseases.


Although these options are sometimes overlooked as a possibility (largely because of ethical or religious, they are worth consideration to some people that do not have any other options.


The literary review included any background information that might be necessary in answering the question and in doing so, completing the aim of the investigation. Unfortunately, through the research done, it is clear to see that the proposed question is not one that can be answered at this moment in time. It therefore translates to a question of whether scientific and medical advances will allow the action of inheritable genetic modification to become a possibility in the future. Along with the possibility of this type of germline gene therapy becoming a reality also comes many questions relating to the ethics of this topic. There is now a strong debate as to whether this IGM will hold more pros or rather more cons for the future of the human race.

Since the question refers to cystic fibrosis as a specific example of one such inheritable disease that germline gene therapy is trying to attempting to prevent, the evaluation will also focus on this disease. As stated previously, cystic fibrosis is a disease that the larger portion of the population of the world is uneducated about. Many people go through half of their lives before being diagnosed and others die without ever recognising that they are suffering from the disease. There has been significant progress made in the area of treatment of cystic fibrosis in the field of somatic gene therapy. Although a faultless medication has not yet been designed, the current rate of successful results and discoveries suggest that it is only a matter of time before a viable treatment is found. The question is whether it will be enough to find a treatment, or if scientists should rather aim for prevention and a cure through IGM.

As we can see from experiments performed on animals such as mice, germline therapy is possible in other organisms. But with such developments it is important to take into account that humans are much more complex organisms than mice. The reactions of the human body are much more complicated and above this it is much harder to do such experiments on humans as there is a strong ethical barrier to overcome. If we assume that IGM will one day be possible on humans, we then have to consider the ethical issues.

On the one hand, IGM will not only provide a cure for serious, chronic diseases such as cystic fibrosis, but can also lead to the prevention of multiple other inheritable diseases. IGM will also be a once-off treatment as opposed to having to pay for, most likely, incredibly expensive somatic cell gene therapy treatment on a regular basis. IGM will provide a full life to people with rare genetic diseases and will allow couples to have children without the fear of passing down their genetic diseases. On the other hand, there is no way of knowing, without extensive experimentation, how changing the germline of a human being will affect the genetic pool in the long run. There is a possibility that diseases could be made even worse than they are already, or that we are ultimately destroying traits that could have been useful in future circumstances of the human race. IGM also opens the possibility of the "super human" race in that people may be able to "design" their children. Not only will this upset the normal interactions of the human race, but it may lead to an unimaginably large separation in classes, as only the wealthy will be able to afford these "genetic enhancements".

Finally, we have been presented with multiple methods of preventing inheritable diseases from appearing in offspring. Although methods such as abortion or adoption may not seem satisfactory to individuals, it is still important to take the risks of IGM into account.


In conclusion it is clear to see that the the answer to the stated question is a definite no. Although the prevention of cystic fibrosis is ones offspring through inheritable genetic modification is not currently possible, it seems promising that the development of such a germline gene therapy could become a reality in the future.

Although it is too soon to say if it is even a strong possibility, IGM should be developed to a point where it can be used on humans. The benefits of this gene therapy being able to cure populations of people from cystic fibrosis or other diseases that shorten their lives far outweighs cons that could be prevented through a well constructed set of laws. There is also the benefit of carrying the cost of only a once-off treatment, as opposed to the constant costs of somatic gene therapy treatment.

In allowing this, it is extremely important to the future of the human race that IGM be used strictly for therapeutic means. It would be vital for governments to impose strict laws, if it develops to this point, against IGM being used as a method of enhance the human genome for favourable characteristics.