Down syndrome, also known as Trisomy 21, is a genetic disorder which affects around one in every 1000 babies born in the UK. The condition was first explored by Dr John Langdon Down in 1862 whilst working in a hospital for mentally disabled people. He recognised similarities in the physical appearance of certain individuals, such as a large tongue and slanted eyes, a condition which is commonly known today as Down syndrome . Most babies are born with a total of 46 chromosomes, 23 from each parent; however, children with Down syndrome have three copies of chromosome 21 instead of two. People with Down syndrome will have an increased risk for some other health issues, such as hearing loss and congenital heart disease. However, they are less likely to develop some cancers .
Scientists in Japan have recently discovered that CRISPR-based methods may be the solution for curing Down syndrome by removing the extra genetic material in these individuals. CRISPR (clustered regularly interspaced short palindromic repeats) is a gene editing technology in which DNA can be inserted, removed or replaced in living cells. This exciting technology is also being developed to produce disease-resistant animals, which may reduce the need for antibiotics, as well as to develop possible treatments for diseases like HIV in humans . Researchers at the University of Amsterdam achieved success when using CRISPR technology to cut out Human Immunodeficiency Virus (HIV) from infected cells in 2024 . This breakthrough prompted other scientists to investigate what else CRISPR can be used for, including the possibility of removing the extra chromosome 21 in those with Down syndrome
Historically, treatments for Down syndrome have focused mainly on symptom management, such as input from speech and language therapists and physiotherapists instead of treating the cause of the condition. The possibility of a future CRISPR-based treatment which permanently targets the cause of Down syndrome would be a major scientific breakthrough and has the potential to transform the future of this condition.
Another possible future treatment for Down syndrome is the use of stem cells. A clinic in India in 2016 claimed to use stem cell injections to treat babies with Down syndrome and reported positive effects such as improved muscle tone in limbs and improved social skills . The stem cells were received from a donated embryo and injected into the children's blood and muscles. Stem cells are important for growth and repair in the human body as they have the potential to self-renew and differentiate into other cell types. Embryonic stem cells are pluripotent, meaning they have the potential to differentiate into all cell types, unlike adult stem cells, making them a valuable resource in medical research. However, critics of the study argue that the stem cell treatment may not have caused the positive results, for example Elizabeth Fisher at University College London states, “There’s no comparison to similar individuals with Down syndrome, and no indication this therapy had any effect whatsoever, so the author has no basis at all for saying the injections were beneficial,” . Whilst stem cell treatment is not a cure for Down syndrome as of yet, it remains a potential future treatment for the symptoms caused by Down syndrome, whereas CRISPR aims at targeting the cause of the condition directly.
However, there is an ethical and moral dilemma around the use of such therapies which alter the DNA of an individual. Some challenges of CRISPR-based techniques are the possibility of causing effects like mosaicism, which is when not all cells are edited, which can impact the efficiency of the gene editing, as not all of the genes will undergo the edit. This could be potentially dangerous in treating inherited diseases, as the presence of unedited cells could result in off-target effects such as new mutations or cells inheriting unedited DNA. This would mean that the child would not be protected from the disease, as the unedited form of the gene would still be present .
There are many moral implications around gene editing, which is why it is illegal to perform such treatments on embryos in most countries. Some would argue that editing embryos is immoral and that people should not be able to ‘design’ their children. If we could, should we? Some would argue that gene editing could one day be used to alter cosmetic traits in babies, such as eye and hair colour, rather than just preventing disease. Furthermore, the babies can not consent to gene editing, raising the issue of restricting their autonomy, which is a major concern in medicine today . Autonomy is one of the pillars of medical ethics, which outlines the patient’s right to make their own medical decisions and choose whether or not to undergo treatments. Down syndrome is also a fundamental part of a person’s identity, which poses the question of whether removing the extra chromosome would impact more than just preventing mental disability, perhaps also possessing the potential to change personality. In addition, the introduction of CRISPR treatments for Down syndrome could be costly, placing some at a disadvantage, and potentially broadening the social inequality and discrimination against people with intellectual disabilities. Some may even argue that eliminating people with Down syndrome is ‘playing God’ and that lots of people with Down syndrome are able to have fulfilling and joyful lives, and that people should not be forced to fit a particular model or socially accepted ideal.