What is CRISPR/Cas-9
Two scientists, Charpentier and Doudna, were researching how bacteria disarmed viruses. They found that their immune system, CRISPR/Cas-9, disarmed and destroyed viruses by cutting their DNA. They then managed to replicate the bacteria’s genetic scissors and control it so it would cut DNA at specific spots.
CRISPR/Cas9 consists of two parts: the Cas-9 protein, which can cut DNA, and RNA, which acts as a guide as it can recognise the sequence of DNA needed to be edited. CRISPR stands for Clustered Regularly Interlaced Short Palindromic Repeats. Scientists first identify the letter sequence of the human genome they want to edit. Then they create a specific guide RNA to recognise this sequence. The guide RNA is joined to the DNA-cutting protein Cas9. This unit is then introduced to the target cells. The unit locates the target letter sequence and cuts the DNA. Scientists can then edit the DNA by modifying, removing, and replacing the sequence. They can even add a sequence. Simply put, CRISPR/Cas9 is a genetic scissor that allows scientists to modify DNA.
Scientists are now using CRISPR to remove faulty DNA and replace it with correct DNA. There is a lot of potential for this product to treat genetic diseases such as sickle cell, cancer, cystic fibrosis, and muscular dystrophy. CRISPR has already been used, for example, on a sickle cell patient named Victoria Grey. Sickle cell disease is a hereditary condition that causes blood cells to be crescent-shaped and not round. This shape causes these blood cells to get stuck in blood vessels, causing chronic pain throughout the body. Bone marrow stem cells were extracted from Grey, and the faulty DNA in them was corrected and edited. Then all her diseased stem cells in her bone marrow were destroyed by chemotherapy. Her genetically modified stem cells were then transfused into her. These new stem cells multiplied, forming blood cells, which spread throughout her body. Grey has had no side effects, and the chronic pain she used to feel due to Sickle cell has gone. The genetic editing was only done on her somatic cells, not her gametes; therefore, the correctly modified cell DNA will not be passed onto her children, and there is still a chance of them inheriting sickle cell from her.
Although this case study proves that CRISPR/Cas-9 is indeed an effective treatment, along with many other cases, it does have some disadvantages. As with any new drug or technology, CRISPR/Cas-9 is expensive. It costs $2–3 million per patient and thus will not be widespread for quite a while. CRISPR/Cas-9 also needs to be implemented with other treatments such as chemotherapy or radiotherapy, which add to the costs. Due to how expensive it is, many LICs cannot afford to use it, whereas HICs can, This would lead to disparity in access to gene editing technology.
One of the first concerns when CRISPR/Cas-9 was released was the potential for designer babies. Babies who have had their DNA edited during gestation, or even if the sperm and egg cells that made them were edited to remove unwanted features such as Down syndrome or unattractiveness, In 2018, He Jiankui, a Chinese scientist, took the first step by announcing that he had created the first gene-edited babies. They were twin girls called Lulu and Nana. He edited the genes of the two babies' embryos using CRISPR to try to make them immune to HIV. There was a major backlash against this based on ethical issues, especially because babies at that time, being embryos, could not give their consent. This was also an entirely new medical field, with no knowledge of if the editing had side effects or the consequences of it in later life. He Jiankui was condemned to 3 years in prison for illegal medical practices as a result of his actions.
At the moment 75 countries including the UK prohibit the use of gene editing on in vitro embryos. Some argue CRISPR/Cas-9 could lead to designer babies with greater intelligence and aptitude than the average human. Since CRISPR/Cas-9 is very expensive at the moment designing babies would only be affordable to the rich. This could lead to greater disparity and inequality in society. On the other hand, CRISPR/Cas-9 could be the miracle cure for many untreatable genetic conditions. He Jiankui's editing of embryos resulted in stricter regulations and restrictions on gene editing worldwide. There are now more rigorous ethical frameworks around it and thus designer babies will not be available for quite a while. However, Gene-editing such as CRISPR/Cas-9 should be used due to the potential it has to solve many serious genetic conditions such as cystic fibrosis. Even if humans reach the stage where it is feasible to make designer babies, by that time ethical laws and other legislation will have made been to deal with it sensibly.