In this series of articles, medical students from across the country will discuss a range of topics from medical ethics to the NHS to public health to medical conditions to clinical governance
Simply put, genetic editing is a technology used by scientists to edit an organism’s DNA. There are many different ways and techniques that can be used to do this, but a popular technique is using CRISPR-Cas 9. This article will outline the process of CRISPR-Cas 9, its application to a case study and explain the pros and cons of genetic editing.
CRISPR-Cas 9 was created based on the defence mechanisms of bacteria. When bacteria are being attacked by viruses and other organisms, they use CRISPR derived RNA and Cas 9 proteins to destroy that other organism’s DNA or RNA by chopping it up.
These proteins and enzymes in the bacteria were modified so that they could be used in a therapeutic way. The Crispr is modified to form specialised pieces of new DNA and the Cas9 is modified to form an enzyme that acts like a pair of ‘scissors’ to cut the organisms original genetic material in specific places.
Crispr Cas9 is a favoured technique as it is less expensive and more efficient than other techniques, and as it is natural (due to it have being made from bacteria), there is a possibility of reducing genetic risk factors and preventing inherited diseases.
In our case study, a group of scientists discovered that people with an abnormal CCR5 gene were highly resistant to HIV infection. This is because without this gene, the HIV virus is unable to enter the white blood cells. This mutation was tested on Chinese twins Lulu and Nana who were made through in vitro fertilisation, the first ever genetically edited babies, in 2018.
Using Crispr Cas 9, Lulu and Nana’s CCR5 genes were edited in an attempt to make them resistant to HIV in vitro before implantation into their mother. The results are yet to be confirmed until they grow older. Not only may these babies be HIV resistant, but there may be different effects. For example, some scientists are suggesting that they will be more intelligent than other humans, or that they may live shorter lives.
On the other hand, this may have not worked at all due to the mosaic effect. This means that some of the twins’ cells will be edited. However, some may still remain unedited and therefore still able to contract HIV.
As you can see, there is a lot of uncertainty still to whether this has been successful or not. If it does turn out to be successful, this may be something that many parents want their unborn babies to have. Crispr Cas 9 may not only be used for HIV resistance, but also for genetic diseases, such as sickle cell anaemia. Patients with sickle cell anaemia require lifelong treatment, and they have symptoms of pain throughout their life. However, just by a small change to their DNA sequence, this could all be taken away, giving the person a better quality of life and reducing medical costs.
However, genetic editing comes with major risk to the germline. The continual editing of genetic makeup of embryos may result in a complete change of the genetic makeup of humans with unpredictable effects. It’s dangerous, and its long-term effects need to be studied thoroughly before it is carried out.
Also, many people disagree with it on a religious basis.
There are a lot of grey areas in genetic editing and knowing the pros and cons of it will definitely help you in your medical interviews.
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