More than 30,000 people worldwide are living with Cystic Fibrosis. Cystic Fibrosis is a recessive genetic disease in which a mutation occurs in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene on chromosome 7. There is a plethora of different mutations that occur, but 70% of mutations that cause cystic fibrosis is the delta f508 mutation. A common cause of cystic fibrosis involves deletion of a codon, 3 nucleotide bases. CFTR proteins resemble a chlorine channel across the membrane of cells that produce mucus, sweat, saliva, tears, and digestive enzymes. The mutation causes a dysfunction of the salt and water balance, resultantly causing thick mucus and salt reduction through excessive sweating. Due to the absence of Cilia and therefore an absence of the process mucociliary clearance, there is a mucus build-up within the lungs. This makes it difficult to breathe, allows poor growth and may result in coughing up mucous.
Clustered Regularly Interspaced Short Palindromic Repeat, also known as CRISPR, is a technology that targets gene mutations in specific DNA to restore it completely. This consists of two components, the Cas9 protein, and the attached guide RNA. CRISPR-Cas9 are enzymes found in bacteria that control microbial immunity. The guide RNA recognizes and locates the mutation in the genome sequence. The Cas9 protein will cut the mutation out of the DNA and either modify, remove or replace the sequence from the DNA chain. The complex is programmable therefore proving to be a precise technology. It is through this process that scientists plan on curing genetic and immune diseases, and substantially improve the immune system.
Cystic Fibrosis, AKA CF, is a recessive genetic disease, therefore, to have CF, there is a requirement of two mutated genes from the parents. However, if there is only one mutated gene the person is classified as a carrier, this can be seen on this pedigree chart. The mutation in the delta f508 gene is caused by the deletion of a codon, three base pairs of the CFTR gene, leading to the loss of phenylalanine. In heterologous cells, defective processing of the DeltaF508 protein results in endoplasmic reticulum retention, proteolytic degradation, and absence of other conductances.
Since 1989 when scientists discovered this CFTR gene, they have been actively seeking ways to cure the various genetic mutations that occur. In the past, and even currently, people with CF have been taken over 50 medication tablets a day to control the disease’s reckless effect on their lungs and digestive system. However, as each CF patient is so individually different, it is hard to find one medication or cure to apply to them all. CF patients also have the option to receive lung transplantation, however, there is a small quantity of accessible lungs. Due to this, 15 in 58 people with CF have died while waiting for a lung transplant. However, successful lung transplants are the most effective intervention in terms of clinical improvement.
In a 2014 study, CRISPR Cas9 was discovered as a possible technology for adult animals. Yin et al. demonstrated that in changing only 6% of cells, CRISPR was curative to tyrosinemia, a single-gene mutation, hereditary condition. Now there has been progress to use CRISPR/Cas9 to cure immune and genetic diseases within people.
One of the major benefits of CRISPR is the efficiency and simplicity of the process. The recorded reasons as to why this is beneficial is due to the embryotic application, the reduction of time required to modify target genes, improvement of the guide RNA replacement processes and also, how the flexibility of procedures has been increased due to the enhancement of experimental conditions.
If CRISPR is to be used therapeutically, it will have to overcome some major obstacles when referring to the process. CRISPR has the potential to target the wrong DNA cells which will result in severe harm to a person. In 2016, AJ Stem Cells state that before human clinical trials begin, researchers must overcome the obstacles of – “the reaction of the human immune system, efficient modes of delivery, determining that a correct copy of DNA is inserted into the sequence, safeguarding against Cas9 proteins cutting at incorrect locations and understanding and controlling off-target effects” (AJ Stem Cells, 2016).
These obstacles are being evaluated and researchers are finding a way to get around this. For example, to reduce the risk of off-target effects, Kleinstiver affirms that there are strategies in place to improve the algorithms to “design guide RNA’s and engineering Cas9 enzymes with higher fidelity and specificity” (Kleinstiver et al., 2016).
The Society of Thoracic Surgeons points out that CRISPR has revolutionized laboratory science. Although there are high risks and apparent obstacles, the has been significant progress over the past 30 years. When looking forward, there are controversial discussions as to whether genome modification technology should be used to edit the human body. A lot of genetic diseases prevent and disrupt the development of organs. As CRISPR has granted the ability to replace genomes and cure genetic diseases, it would be beneficial to edit the genomes when the human is in embryonic form as this would prevent the disruption of development. This is called germline engineering; additionally, this will prevent the inheritance in future generations. However, an ethical dilemma arises when considering CRISPR Cas9 on embryos. Adults can give full consent, whereas embryos cannot provide informed consent. Patients who have incurable diseases are often willing to participate in clinical trials as they live a quality-compromised life and are presented with no alternative treatments. A consideration that must be made with the embryotic application is the stage of development of which the embryo should be operated on.
The commencement of human trials in CRISPR can lead to the concern of further trials on embryos then into ‘designer babies’. The term ‘designer babies’ is when one can pick and choose exactly what traits or characteristics, they want their child to have. This removes the naturality of conception and birth, which raises ethical issues.
The cost of CRISPR Cas9 ranges from $500,000 to $1.5 million. This raises the question of whether the technology is worth funding. If the obstacles are overcome and CRISPR/Cas9 is applied to humans, there will have to be strict lines drawn to ensure that the technological processes are still ethical. For example, CRISPR needs funding but should only be used for curing diseases and not to advance the normal body. Laws will have to be made by the government to assess what is in measurable terms of this technology.