Down syndrome (DS) is the most common genomic disorder of congenital cardiac defects and intellectual disability. The most common form of DS, also known as trisomy 21, is caused by non-disjunction during meiosis of either the sperm or egg, resulting in an embryo with three copies of chromosome 21 instead of the usual two. Alternatively, about 1% of DS cases present a mosaicism of cells in the body with 46 or 47 chromosomes when the non-disjunction takes place at a later time in the embryo development; and others (about 4%) present a type of DS known as translocation, that happens when a fraction of chromosome 21 attaches to another chromosome, usually chromosome 14. The national incidence of DS is estimated to be around 1/800 births, meaning that there are about 60000 people living with DS in the UK. The life expectancy for those with the syndrome has increased from 25 years in the 1980s to 60 years currently thanks to advances in congenital heart disease surgery.
The discovery of the syndrome
DS was first described by the English physician John Langdon Down in 1866. In his manuscript, Dr Down reports that a large proportion of the patients referred to him shared a striking pattern of intellectual disability and physical traits that led him to attempt an ethnic classification, hypothesising that those affected with the syndrome were genetically related to Mongolian ethnicity, given the physical similarities. It wouldn’t be until later in 1959, following the advances in karyotype imaging techniques, that French paediatrician and geneticist Jérôme Lejeune described the triplication of chromosome 21 as the cause of the syndrome.
Common disorders in Down syndrome
The genetic imbalance resulting from the extra copy of over 200 protein-coding genes contained in chromosome 21 gives rise to a plethora of manifestations. Two of the most commonly known are the already mentioned intellectual disabilities and congenital cardiac defects, particularly atrioventricular septal defect, which is generally surgically corrected after birth. But people with DS are also at higher risk of suffering Alzheimer's disease, epilepsy, obesity and diabetes, immune dysfunction, hypothyroidism, small stature and low bone density and leukaemia, among others. However, the syndrome also offers some protection against other conditions, for instance, DS is associated with a lower incidence of solid tumours, hypercholesterolemia and hypertension.
World Down Syndrome Day 2023
World Down Syndrome Awareness Day has been observed every year on 21st March since officially proclaimed by the United Nations in 2012. Last year, researchers working in the field of DS from Queen Mary University of London, King’s College London, the Francis Crick Institute and University College London met at the Francis Crick Institute with people with DS, their families and carers to celebrate the day. Despite intensive rain and rail strikes, we had over 100 attendees ranging from whole families with children with DS and other siblings, a mother with a young baby, older adults with their carer and single parents.
A selection of photos from WDSD 2023
The event had been months in the making, involving weekly planning meetings and was supported by a public engagement grant from the British Pharmacological Society. The organising committee was led by ECRs, PhD students and BSc students. We prepared a day with talks from experts and early career researchers and interactive activities that were available throughout the day. The day started with short science talks from the early career researchers. These talks introduced the attendees to the array of disciplines on DS that are being studied in London-based universities: the interplay between hormones, environment and healthy aging in DS, brain imaging in young babies, the genetic causality of congenital heart malformations, Alzheimer’s disease and language and cognition.
After a short break, the next session showcased the Workfit programme from Down’s Syndrome Association, which aims at bringing together employers and jobseekers who have DS. Next on the agenda was a talk from a person with DS and his career, describing their experiences participating in research studies.
Following lunch, three experts on sleep, thyroid disorders and mental well-being gave more exhaustive talks and welcomed a Q&A session. Throughout the day, eight stalls with interactive activities were running in the background. We made neurons with Play-Doh, brain hats out of paper, explained mouse models of DS using Lego blocks, showed how the brain and heart work with anatomical models and promoted healthy living habits at our photo booth where Polaroid pictures were taken to be later used to create a poster with positive affirmations.
Looking back
We received excellent feedback from the participants, who would like to see “more events on different days”. They enjoyed learning from the short talks about the different areas of research: “Good to know of all the different areas of research around London” and found the expert talks very informative: “The thyroid talk was useful because it spoke about how the tests are used by professionals. Help us as carers/family”. Overall, the highlight of the day was the interaction between science and the public: “Excellent day, very informative. Long time for open discussions”, and “I enjoyed meeting other parents”. We and our participants “can’t wait until next year”.
If you have an idea for WDSD 2024 or would like to get involved, please email Cristina Perez-Ternero.
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