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The Facts & History of Down Syndrome: just the interesting stuff we should all know

Updated: Apr 14, 2023

Despite tremendous recent advances in the knowledge and inclusion of those with Down syndrome, there remain many misconceptions even within the Down syndrome community itself. So today let's lay out the facts:


John Langdon Down

1866: English physician John Langdon Down publishes an accurate description of a person with Down syndrome

1876: Initial association between "premature senility" and Down syndrome is made, 70 years before the link between Down syndrome and Alzheimer's disease is published

1946: Dr. Benjamin Spock suggests babies born "mongoloid" should be immediately institutionalized

1959: French physician Jerome Lejeune identified Down syndrome as a chromosomal condition

1965: World Health Organization rejects the term "mongolism" and accepts Down syndrome as standard terminology

Lifespan & Frequency

The average lifespan for people with Down syndrome has more than doubled in the last few decades. Most attribute this rise to a more progressive view of people with Down syndrome which has helped nearly eliminate the inhumane practice of institutionalizing people with Down syndrome. Additionally, a greater awareness of the health risks and medical advances to address especially newborn health complications has improved life expectancy. Today, life expectancy continues to grow as the Down syndrome community and society at large view people with Down syndrome as important and contributing members.

The frequency of lives births with Down syndrome has increased in recent years from 1 in 1087 (1994) to 1 in 691 (per CDC in 2011). The increase may be due, in part, to families choosing to delay starting a family and to families choosing to proceed with delivery after prenatal testing. Still, even today 67% of those with a prenatal diagnosis of Down syndrome opt to terminate their pregnancy. Continued efforts by local Down syndrome organizations and others to support and educate parents on the new world of opportunities and possibilities continue to make a difference.

Though actual statistics regarding the population of people with Down syndrome are not known, estimates are approximately 400,000 in the US and likely over 6 million worldwide. These numbers are expected to grow as the frequency and life expectancy age continue to increase.

Types of Down syndrome

Did you know there are three types of Down syndrome?

  1. Trisomy-21: each 21st chromosome has an extra copy attached (95%)

  2. Translocational: part or all of the extra 21st chromosomes attach to various other chromosomes (3%)

  3. Mosaic: some but not all 21st chromosomes have an extra copy attached (2%).

Certainly, the type of Down syndrome has an impact on health challenges and intellectual differences.

Down Syndrome Research

Research into prevention, treatment, and management of Down syndrome and its many health risks has been underway since the first lab mouse with Down syndrome was "created" in 1974. Big boosts to research and funding have been associated with the link of the 21st chromosome to Alzheimer's disease (1987) and the mapping of over 320 genes associated with the 21st chromosome (2000).

Yet as recently as 2006, Down syndrome remained the least-funded major genetic condition. The National Institute of Health (NIH) funded only $14Mln for Down syndrome research within its $28.5B budget in 2006. Funding levels are improving but remain dreadfully low despite the fact Down syndrome remains the most frequent chromosomal disorder in the US.

Consider donating your time or resources to your local Down syndrome association, a national organization such as the National Down Syndrome Society (NDSS), National Down Syndrome Congress (NDSC), Global Down Syndrome Foundation (GDSF), or LuMind IDSC Foundation which serves as a bridge between the Down syndrome community and the research community.

Beyond Down Syndrome is proud to donate a portion of all book sales proceeds of The Essential Guide to LuMind IDSC to support Down syndrome research specifically focused on the link with Alzheimer's disease. Did you know that 12% of the US population will be afflicted by Alzheimer's but 95% of the Down syndrome community will have Alzheimer's by the age of 65, often exhibiting first signs decades earlier? Together we can make a difference!

Commonly Accepted Terminology

Finally, it is helpful for us all to be aware of and educate others on proper vernacular:

  • Rather than address someone as a "Down syndrome child" they should be referred to as a "child with Down syndrome"

  • The full phrase of Down syndrome is preferred rather than "he has Downs"

  • In the last couple of decades, the term "mental retardation" has largely been retired in lieu of "intellectual disability"

  • The proper written term is "Down syndrome," not "Down's syndrome" or capitalized "Down Syndrome" (unless used in a title).

The greatest advocates for our children, family, and friends with Down syndrome are themselves and ourselves. It's important we all know the facts.

Join us starting in March for weekly blog articles on a variety of subjects important to self-advocates and families with Down syndrome, including how to foster independence, how to manage common health risks, important financial and legal resources you should know, how to promote school, work, and societal inclusion, and how to evaluate housing options and prepare for your self-advocate's future of independence.

This week's article has been compiled with resources from the National Down Syndrome Society and the Global Down Syndrome Foundation. Check them both out for more information and resources.


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