Down Syndrome

Written by: Sasha Lovitz

Edited by: Christine H.

Down syndrome, also known as Trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is one of the most prevalent genetic disorders worldwide, affecting individuals across all races, ethnicities, and socioeconomic backgrounds. According to the Centers for Disease Control and Prevention, Down syndrome occurs in approximately 1 in every 700 live births in the United States, equating to around 6,000 babies born with the condition each year (CDC, 2023). 

The most common cause of Down syndrome is nondisjunction, an error in cell division during the formation of eggs or sperm. This results in a sperm or egg cell with an extra copy of chromosome 21. When this cell contributes to a child's genetic makeup, the result is Trisomy 21–three copies of chromosome 21 instead of the usual two. This type accounts for about 95% of Down syndrome cases (Bull, 2020). Translocation, where a portion of chromosome 21 becomes attached to another chromosome, accounts for about 3-4% of cases. Mosaicism, in which some cells have the typical 46 chromosomes and others have 47, occurs in about 1-2% of cases and often results in milder symptoms (NDSS, 2024). 

Children with Down syndrome typically exhibit certain physical traits, including a flat nasal bridge, almond-shaped eyes that slant upward, a single deep crease across the palm, and hypotonia (low muscle tone). Cognitive delays are also common, with most individuals showing mild to moderate intellectual disability. Despite this, many individuals with Down syndrome are capable of learning, forming meaningful relationships, and participating in academic and social activities, especially with early intervention and proper support (NICHD, 2017).

People with Down syndrome are more likely to develop a range of health issues, including Congenital heart defects, which affect approximately 50% of newborns living with the condition, requiring early detection and often surgical correction (Bull, 2020). They also face an increased risk of respiratory infections, hearing and vision problems, gastrointestinal disorders, thyroid dysfunction, and obstructive sleep apnea. One significant concern is the early onset of Alzheimer’s disease, which has been linked to the extra copy of the amyloid precursor protein gene located on chromosome 21 (Head et al., 2016). With the advances in medical care, early interventions, and community support, the life expectancy for people living with Down syndrome has increased significantly. In 1983, the average life expectancy was around 25 years; today, it is over 60 years (NDSS, 2024). 

Educational inclusion has become a cornerstone of support for individuals with Down syndrome. Research shows that children included in mainstream classrooms benefit socially and academically, while their peers without disabilities also gain empathy, diversity awareness, and social skills (de Graaf et al., 2013). Many individuals with Down syndrome graduate from high school, attend post-secondary programs, and develop vocational skills that enable them to participate in the workforce. Organizations like the National Down Syndrome Congress and the Global Down Syndrome Foundation for full inclusion and support for families and educators. 

The diagnosis of Down syndrome can initially be overwhelming for parents. However, studies show that most families adapt positively over time. Skotto et al. (2011) found that nearly 99% of people with Down syndrome said they were happy with their lives, and 97% of siblings expressed pride in their brother or sister with the condition. Parents often report that raising a child with Down syndrome enriched their family life and offered new perspectives on joy, resilience, and community. Support networks, counseling, and access to early childhood intervention services are crucial in helping families navigate the challenges and celebrate the achievements of children with Down syndrome. Peer groups and advocacy organizations also offer a sense of belonging and empowerment. 

Ongoing research into Down syndrome is shedding light on the underlying genetic and neurological mechanisms of the condition. Scientists are exploring how the extra chromosome affects brain development, hoping to develop targeted therapies to enhance cognitive function. For example, some studies are investigating the role of specific genes in neurodevelopment and how pharmaceutical or gene-based interventions could mitigate intellectual disability (Lee et al., 2020). 

Public awareness and representation of individuals with Down syndrome have improved significantly over the past few decades. Increased visibility in media, politics, and sports has helped reshape public perceptions and challenge outdated stereotypes. Actors with Down syndrome have taken on significant roles in film and television, such as Zack Gottsagen in The Peanut Butter Falcon, which has been praised for its authentic representation. 

Global awareness campaigns such as World Down Syndrome Day (March 21) highlight the contributions of individuals with Down syndrome and promote advocacy for equal rights and opportunities. These efforts encourage communities to embrace diversity and support policies that promote inclusion in education, healthcare, and employment. 

Down syndrome is a complex genetic condition that influences physical, cognitive, and emotional development. While it presents notable challenges, it is accompanied by a broad spectrum of abilities and potential. Advances in medicine, education, and social inclusion have transformed the lives of individuals with Down syndrome, allowing them to live longer, healthier, and more fulfilling lives. Continued research, advocacy, and public awareness are essential to breaking down barriers, promoting acceptance, and ensuring that individuals with Down syndrome are fully included and valued in society.

References

Bull, M. J. (2020). The New England Journal of Medicine, 382 (24), 2344-2352. https://doi.org/10.1056/nejmra1706537 

Centers for Disease Control and Prevention. (2023). Facts about Down syndrome. https://www.cdc.gov/birth-defects/about/down-syndrome.html

de Graaf, G., Van Hove, G., & Haveeman, M. (2013). More academics in regular education? A longitudinal study of students with Down syndrome in the Netherlands. European Journal of Special Needs Education, 28(3), 312-331. https://doi.org/10.1111/j.1365-2788.2011.01512.x 

Head E, Lott IT, Wilcock DM, Lemere CA. Aging in Down Syndrome and the Development of Alzheimer's Disease Neuropathology. Curr Alzheimer Res. 2016;13(1):18-29. https://doi.org/10.2174/1567205012666151020114607 

National Down Syndrome Society. (2024). What is Down syndrome? https://ndss.org/about 

National Institute of Child Health and Human Development. (2017). Down Syndrome: Condition information. https://www.nichd.nih.gov/health/topics/down/conditioninfo 

Skotko, B. G., Levine, S. P., & Goldstein, R. (2011). Having a son or daughter with Down syndrome: perspectives from mothers and fathers. American journal of medical genetics. Part A, 155A(10), 2335–2347. https://doi.org/10.1002/ajmg.a.3429