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34 Important Down Syndrome Statistics & Facts to Be Aware Of

by Dusan Goljic, Pharm.D.

It is a well-known fact that our genes determine our physiological features. They hold the information about everything, from teeth arrangement and eye color to our most distinguished psychological preferences.

Since it was clinically recognized over 150 years ago, Down syndrome (DS) has been the most researched, described, and scientifically presented genetic indisposition. However, there’s a lot of misinformation about this condition, due to the commonly attached stereotype.

It is time to raise Down syndrome awareness. In the following article, we’ve collected widely unknown and astonishing Down syndrome statistics and facts, in order to inform and break common misconceptions.

In the past, people with Down syndrome have been treated as socially undesirable. Some of the main misconceptions were that they can not achieve maturity and socialization, and become healthy and productive members of society. Until the late 20th century, they were institutionalized and treated as outcasts. The article before you shows the real picture of how many people have Down syndrome, what disabilities and advantages they have, and how happy they actually are. 

Top 10 Down Syndrome Facts and Stats

  • There are more than 400,000 people with Down syndrome in the US and over 6,000,000 worldwide.
  • 38% of Americans know someone with this condition.
  • There are 3 different types of Down syndrome.
  • Prenatal diagnostic testing is nearly 100% accurate.
  • It is hereditary in less than 1% of the cases.
  • The likelihood of having a child with Down syndrome increases with maternal age.
  • 67% of pregnancies with detected Down syndrome are terminated.
  • 6,000 newborns are born with Down syndrome annually.
  • The life expectancy of people with Down syndrome is up to 60 years.
  • 77% of the people with this syndrome develop Alzheimer’s disease.

General Down Syndrome Statistics and Facts

1. Down syndrome is a genetic condition.

(Genetics Home Reference)

Down syndrome occurs is a chromosomal condition, associated with characteristic facial appearance, weak muscle tone, and cognitive disability. Statistics on babies born with Down syndrome show they tend to have a variety of birth defects, slower childhood development, and higher incidence of pathologies in adulthood. Although living with this condition can present a challenge, most of the people grow into socially integrated individuals.

2. People with Down syndrome have 47 chromosomes.

(Journal of Clinical Medicine)

Down syndrome occurs at the time of cell division that follows the fertilization of the egg cell. This is known as the zygote phase. Since every parent provides 23 chromosomes in the process, the normal human genome consists of 46 chromosomes. Due to unknown factors, at the time of cell division, an extra chromosome 21 is created. Therefore, the created organism has an extra chromosome, making it a total of 47.

3. There are 3 types.

(CDC)

Trisomy 21 – 95% of people with DS have this type, and every cell of their body has three copies of chromosome 21, instead of the regular two.

Translocation Down syndrome – With the prevalence of about 3%, this happens when an extra part of chromosome 21 gets attached to another chromosome in the genome.

Mosaic Down syndrome – Affecting about 2% of DS cases, these people have an extra chromosome only in some cells, while other cells have regular chromosome count. 

4. There is no cure for Down syndrome.

(US Department of Health and Human Services)

Given that it is still unknown what causes Down syndrome, there is no cure for it. However, there are treatments that can ease early childhood development, such as physical therapy, speech therapy, and occupational therapy. During adolescence, specific approaches, such as emotional and behavioral therapy, can produce significant results. An individual approach is necessary in order to achieve optimal developmental outcomes.

5. According to statistics, Down syndrome is hereditary in less than 1% of cases.

(National Down Syndrome Society)

Although it is a genetic condition, Down syndrome does not run in the family.  Trisomy 21 and Mosaic-type DS can not be inherited. However, translocation DS can have a heritable component in less than one-third of the cases, which is less than 1% overall.

6. The incidence of Down syndrome is almost equal regardless of race or economic status.

(American Journal of Epidemiology)

Wealth and education do not influence the occurrence of this syndrome. Each of the three types have been recorded in all races, regardless of religious preferences or geographical background. However, Down syndrome life expectancy statistics show that African American infants have a lower survival rate during their first year.

7. 95% of people with Down syndrome share its main physical features.

(US Department of Health and Human Services)

Down syndrome is a very recognizable condition. It is also called “Mongolism.” Most common physical traits are: 

  • Flattened facial profile 
  • Round-shaped face
  • Small head, ears, and mouth 
  • Almond-shaped and upward slanting eyes 
  • Wide and short hands with short fingers
  • Poor body muscle tone

Individuals with trisomy are usually overweight and tend to have hormonal disorders.

Down Syndrome Statistics About Comorbidities

Down Syndrome Statistics - Comorbidities

8. People with Down syndrome are 50% more likely to have other diseases, compared to the general population.

(US Department of Health and Human Services)

Stats on Down syndrome comorbidities show several patterns of additional pathology, that develops in the majority of cases:

  • Hearing loss (75%)
  • Ear infections (50%–70%)
  • Sleep apnea (50%–75%)
  • Eye diseases (60%)
  • Thyroid disease (18%)

Other conditions that are consistent with this condition include hip dislocation at childbirth, leukemia, and Iron deficiency.

9. 77% of people with Down syndrome over 50 have Alzheimer’s disease.

(PubMed Central) 

Although people with Down syndrome have mild to moderate cognitive impairment, active intellectual decline presents the main challenge for the management of this condition today. According to Down syndrome statistics, age is the main predictor of the onset of Alzheimer’s disease.

An excessive accumulation of amyloid plaques has been identified in people with all types of the condition at the age of 35. At the age of 40, up to 55% of them reveal symptoms of dementia, and by the age of 60, the majority has fully developed AD.

10. 7% of people with Down syndrome have autism.

(Down Syndrome Education)

There is an increasing number of children with Down syndrome being diagnosed with Autistic Spectrum Disorder (ASD). Observational studies state that 16.7% of people with learning disabilities have ASD. 

Interestingly, Down syndrome facts and statistics show that individuals with this condition have some inbuilt predispositions for social skills which makes it harder for them to develop ASD than the general population.

11. People with Down syndrome have mild to moderate cognitive impairment.

(Cambridge Cognition)

Brain development is usually delayed in people with Down syndrome. Due to an extra chromosome, certain parts of the brain develop more slowly, thus creating an intellectual impairment that is untreatable and persists throughout life. The IQ rate of Down syndrome people varies from mild (IQ: 50–69) to moderate intellectual disability(IQ: 35–50).

The brain of a person with DS is smaller than usual and certain parts, such as the hippocampus and the cerebellum, are less developed. Therefore, the physiological functions, such as learning, memory, and physical coordination are less likely to be fully developed.

12. Mosaic Down syndrome facts show higher developmental preferences.

(International Mosaic Down Syndrome Association)

Individuals with Mosaic-type syndrome have 47 chromosomes in some cells only. They have common syndrome traits expressed in minimal amounts, that seem almost unrecognizable. Their IQ is usually 12 to 20 points higher than in the non-mosaic group.

Down Syndrome Statistics Worldwide

Down Syndrome Statistics - Worldwide

13. It is estimated that more than 400,000 people in the US have Down syndrome.

(Global Down Syndrome Foundation)

A US nationwide poll that was conducted by GDSF presented more realistic Down syndrome statistics in 2018.  According to the poll, 38% of Americans know someone with the syndrome. The condition was officially recognized as socially important, and this was one of the factors that inspired the creation of a better healthcare plan in 2018.

14. There is evidence that there are more than 6 million people with Down syndrome worldwide.

(Healthline)

Due to the lack of consistent data regarding the incidence of Down syndrome, it is hard to accurately quantify this population. However, Down syndrome awareness has significantly increased over the last five decades. This has generated the need for more structured data, which has led to the multi-million-people figure.

15. The prevalence of Down syndrome in the US is 1 in every 691 live births.

(CDC)

Trisomy 21 is the most common genetic defect that occurs in newborns in the US. With the prevalence of 14.47 per 10,000 live births, it is estimated that about 6,000 newborns are born with DS annually. 

16. The US has higher rates of Down syndrome live births than Europe.

(WHO)

The European office of the WHO published in 2018 a data indicator that reveals Down syndrome statistics by country. The top 5 European countries by the number of live births annually are:

  • Ukraine – 445
  • United Kingdom – 351
  • The Netherlands – 330
  • Germany –298
  • Belgium – 259

According to the data collected from 1970 to 2016, Turkey and Russia are the only European countries that have comparable live birth rates to the US. However, they are multicontinental countries, which is why they haven’t landed in the top five of the above list.

Down Syndrome Statistics and Facts: Pregnancy and Childbirth

Down Syndrome Statistics - Pregnancy

17. The likelihood of having a child with Down syndrome increases with the age of the mother.

(NHS INform)

The Down syndrome statistics by race show a low impact of the ethnical background on pregnancy outcomes. Furthermore, the syndrome’s occurrence has nothing to do with anything parents did during the pregnancy. There is also no correlation between incest and Down syndrome.

There is, however, a clear connection between maternal age and the chance of conceiving a child with this syndrome. A woman of 20 has a 1 in 1,500 chance to conceive a child with Down syndrome, whereas a woman over 40 has a 1 in 100 chance. 

18. Prenatal diagnostic testing is nearly 100% accurate.

(National Down Syndrome Society)

According to NDSS, the Down syndrome miscarriage rate is significantly lower today than two decades ago, and this is due to the accuracy of prenatal diagnostics. The most commonly used diagnostic tests in the detection of the trisomy are:

Chorionic villus sampling (CVS) that examines the genetic properties of the materials from the placenta. It is done between the 11th and 14th week of pregnancy.

Amniocentesis that examines the amniotic fluid, and is done between the 15th and 18th week of pregnancy.

Percutaneous umbilical blood sampling (PUBS) that examines blood from the umbilical cord. PUBS is usually done after the 18th week of gestation.

19. The sex of the baby with Down syndrome is determined by the age of the parents.

(PubMed Central)

According to Down syndrome statistics by age, younger couples tend to have more male babies, whereas couples older than 35 tend to have more female children with Down syndrome.

20. Detecting common physical traits is not enough for postnatal diagnosis.

(Boston Children’s Hospital)

At birth, the baby is examined for the presence of certain physical characteristics, such as low muscle tone, or a deep crease across the palm of the hand. However, these features may be present in children without the syndrome. Therefore, Down syndrome karyotype testing is mandatory.

21. 67% of pregnancies with Down Syndrome are terminated.

(Prenatal Diagnosis)

Down syndrome pregnancy termination statistics show a decrease in abortion rates. The assessment of data gathered from 1995–2011 suggests higher rates of newborns in the US. The lower abortion rates could reflect the progress in management, medical help, and support that has been established through the years. Over the last two decades, the percentage of women giving birth has increased from 4.8 to 18.6%.

22. 50% of children with Down syndrome are born with a congenital heart defect.

(CDC)

Trisomy 21 is associated with slow heart development, both in utero and after birth. There are a variety of heart problems that may occur, and many of them may need surgical interventions.

23. People who already have a child with Down syndrome have higher chances of having another baby with the condition.

(Medscape)

Given the known statistics of Down syndrome, the risk of having another child with the same condition varies depending on the gene carrier. Recurrence of translocation is 3% if the father has the gene, and about 10–15% if the mother carries it.

24. Down syndrome is the leading prenatal cause of cognitive disorders in newborns.

(eMedicineHealth)

The causes of intellectual disability at childbirth can be divided into the following three categories:

Prenatal causes – Those that happen before the time of childbirth. Trisomy 21 is the leading genetic cause of intellectual disability.

Perinatal causes – Those that happen around the time of childbirth, such as malnutrition, or oxygen deprivation.

Postnatal (acquired) causes – Those that happen shortly after the time of birth, and may include trauma or intoxication.

25. 54% of the miscarriages happen between the 11th and 16th week.

(PubMed Central)

Research shows that the Down syndrome miscarriage rate is significantly higher than in non-Down pregnancies. 32% of pregnancies are lost between the times CVS and amniocentesis are performed, and a total of 54% of pregnancies are lost before the term.

Adults with Down Syndrome Facts and Stats

Down Syndrome Statistics - Adults

26. Today, the life expectancy of a person with Down syndrome is up to 60 years.

(European Journal of Public Health)

The estimated lifespan of a person with Down syndrome in the 1940s was approximately 12 years; in 1983 it was 25 years; whereas today a person with this condition can live up to six decades in developed countries. A dramatic increase in longevity within this short period is due to a better understanding of the nature of the condition.

27. Down syndrome mortality rates are higher than in the general population.

(Journal of Epidemiology and Community Health)

The main causes of the higher Down Syndrome mortality rate across every life stage include pneumonia and respiratory infections (about 30%), followed by congenital heart problems (17%), and cardiac, renal or respiratory failure (10%). 

28. People with Down syndrome are no longer institutionalized.

(Global Down Syndrome Foundation)

Before the 1980s, people with Down syndrome were generally considered as “retarded,” and their treatment was conducted within specialized institutions. In 1983 the social perspective shifted to a more human approach, where they were allowed to be with their families and to contribute to their communities.

Down syndrome awareness efforts have given dramatic results regarding longevity, personal development, and social integration.

29. People with Down syndrome can have children.

(Down’s Syndrome Association)

Fertility rates in people with Down syndrome are lower than in the general population. Down syndrome statistics show that about 50% of females with the syndrome are fertile and have a menstrual cycle similar to their peers. If they conceive with a non-DS father, the chances of having a baby with the syndrome are between 35%–50%.

Males with Down syndrome have significantly reduced fertility rates than females. Although there is evidence that both mothers and fathers with Down syndrome can produce a healthy child. DS mothers are more likely to have difficult pregnancies and have a higher risk of miscarriages. 

30. 99% of people with Down syndrome are happy with their lives.

(PubMed Central)

According to a 2013 nation-wide study that included people with Down syndrome, 97% of participants stated that they like who they are, and 96% of them reported that they like the way they look. 86% of them think that they could make friends easily, and 99% of them love their families. 27% of the participants also stated that they needed medical experts to better attend to their needs.

FAQs

Why is it called “Down” syndrome?

The condition was first noted by English physician John Langdon Down in 1862. He recognized it as a distinct type of physical and mental disability and published an accurate description of it in his scholarly work in 1866. This way, the physician received recognition as the “medical father of the condition.” Since then the syndrome has borne his name.

How many chromosomes do humans have?

Chromosome count or “karyotype” is a term that determines the number and the microscopic appearance of chromosomes of an organism. Normal human karyotype has 23 pairs of chromosomes or 46 chromosomes in total. During fertilization, the new organism gets 23 chromosomes from both the mother and the father. A Down syndrome karyotype has 47 chromosomes.

What causes Down syndrome?

Down syndrome is caused by an error in cell division called “nondisjunction.” Before conception, a pair of chromosomes 21 in either the mother or father fails to separate, and the fertilized egg receives an extra chromosome. As the newly created embryo divides, this additional 21st chromosome replicates in every cell of the body.

What are the proper terms when dealing with Down syndrome?

The only correct way to address individuals with this condition is: “people with Down syndrome.” 

Some mixed terminology still remains from the past, such as: Downs, Down’s syndrome, Mongoloids, Down syndrome child or Down’s child. According to NDSS, these terms are misleading, derogatory, and describe the person with the condition in a meaningless way.

The term “Down’s” refers to possession, and is therefore wrong. The term “Mongoloid” is an old hurtful description and that’s unacceptable today. People with Down syndrome are not “afflicted by” the condition, and they do not “suffer” from it.

Conclusion

Over the last half-century, tremendous progress has been made in the understanding and treatment of people with Down syndrome. Today, these people receive better medical care and social integration opportunities. This has made the world a better place for them, increasing the average Down syndrome life expectancy by five times.

Although cognitively impaired and physically different, they are complete individuals, with their own sense of beauty, taste, and freedom of choice. They are usually very sensitive and can develop talents beyond their limitations. With the progress of modern medicine, the future holds promise for better, healthier and considerate tomorrow.

Understanding Down syndrome statistics and facts is essential in the world of medical and technological progress. It is also a reminder that sometimes, further down the offspring line, the genetic signature in our chromosomes can express a part of Mozart, Tesla, or Einstein. And sometimes, gene pairing can unknowingly go on a different path and create a person with Down syndrome.

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