Down Syndrome: 10 Fascinating Facts You Should Know

Imagine being struck by a disease as soon as you are born and having to live with it, although where there is proper care, there is an amazing cure. Similar is the situation of Down syndrome, read on to know more!

Down Syndrome: 10 Must-Know Facts

Down syndrome is a medical condition in children when their cell gets three copies or an extra partial pair of chromosome 21, also giving its another known name, trisomy 21.

This condition prohibits their healthy full-body development and was named after British doctor John Langdon Down after fully describing this syndrome in 1866.

Most of the disabilities caused by this condition stay lifelong and reduce their life expectancy rate. Nevertheless, the range of disability severity varies from person to person.

The average IQ of a young adult who has Down syndrome is 50, parallel to the mental growth of an eight or nine-year-old kid. The right educational environment and proper care can improve their living condition, but there is no cure for Down Syndrome.

Causes of Down Syndrome

Both parents pass 23 chromosomes each to the baby, 46 in total. But children with Down syndrome end up with three copies, or an extra partial copy of chromosome 21, rather than the usual two.

The reason is that chromosome 21 failed to separate properly. This disability prohibits the brain and body from complete development.

Types of Down Syndrome

There are three types of Down Syndrome:

  •  Trisomy 21

10 facts about down syndrome
“Down Syndrome (Trisomy 21)” by the National Institutes of Health (NIH) is licensed under CC BY-NC 2.0

In Trisomy 21, an extra copy of chromosome 21 is present in every cell after chromosome 21 fails to separate properly during sperm or egg development.

Trisomy 21 is the most common kind of Down Syndrome. The percentage of parents involved in causing this disability is different – 88% of nonseparation happens in the mother case, 8% occurs in the father, and 3% happens after merging egg and sperm.

  •  Mosaicism

An extra copy of chromosome 21 is not present in every cell of children in Mosaicism1, resulting in fewer symptoms than in trisomy 21.

  •  Translocation

This type of Down Syndrome can be hereditary and occurs in only 2%- 4% of cases, resulting in only an extra pair of chromosome 21 in children.

Parents with translocation are mentally and physically normal, but they have a higher chance of reproductive cells with an extra chromosome 21.


Children diagnosed with Down Syndrome always have physical, mental, heart, sensory, and visionary disabilities, ranging from low, moderate, to severe levels. They also have poor immune systems.

Here are those symptoms:

  • Physical Disabilities

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Image from Pexels

Children and adults with Down syndrome may have all or some of these physical conditions:

Slanted eyes, small chin, flattened nose bridge, short neck, low sets ears, obstructive sleep apnea, wider face, shorter height.

They also have protruding tongues due to the small size of the mouth, extra space between the second toe and big toe, short fingers, excessive joint flexibility, obesity, lax muscles, a single line on the palm, and some others.

  • Sensory Issues

More than half of the people with Down syndrome are affected by vision and hearing disorders. 38% – 78% of children are affected by the hearing disorder, often beginning in the 1st year of life, partly due to poor eustachian tube function.

Otitis media with effusion and chronic ear infection are the main cause of the hearing disorder

38% – 80% of children are affected by vision disorders. 15% of them have cataracts, brushfield spots can occur in 38% – 85%, glaucoma, and a thin, cone-shaped cornea are also common, while 20% – 50% have strabismus – the individual movement of eyes.

  • Neurological Disorder

Slow mental growth delays development in almost all children and adult life with Down Syndrome. They started to crawl around eight months rather than at five months while walking in the 21st month rather than at 14 months.

Their average IQ is 35 – 70. They can better understand other people rather than speaking, either due to stuttering or irregular & rapid speech. Adults who are 40 years or older can have Alzheimer’s disease.

Some adults may develop symptoms of depression and anxiety2. Children 8% and adults – 50% are at a higher risk of epileptic seizures.

  • Heart Ailment

Around 40% of newborns with Down Syndrome are born with congenital heart disease, while in some cases, it can develop when children start to age. 

The most common heart defects in them are the Atrioventricular Septal defect and Ventricular Septal defect.

  • Cancer

Children and adults with Down Syndrome can have a higher risk of Acute Lymphoblastic Leukemia, Testicular Cancer, and Acute Megakaryoblastic Leukemia.

The chance of Acute Lymphoblastic Leukemia is 20 times more common, while Acute Megakaryoblastic Leukemia is 500 times more common.

At the same time, there is a higher chance of happening of testicular germ cell cancer.

  • Endocrine Disorder

Hypothyroidism and type 1 diabetes 3mellitus are the most common in a person with Down syndrome. 20% – 54% of people with Down syndrome suffer from thyroid gland problems.

  • Teeth Abnormalities

10 facts about down syndrome
By tariqkhajar, licensed under CC BY-NC-ND 2.0

People with Down Syndrome have crowded teeth, delays in the shedding of baby teeth and eruption of adult teeth, and missing and uneven-structured teeth.

A higher rate of teeth grinding, mouth breathing, and jaw clenching are also common.

  • Poor Fertility Rate

While 30% – 50% of females with Down syndrome can reproduce, males have an almost non-existence chance of fathering kids.

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Image by Daniil Slavinski from Pixabay

Globally, 10 in 10,000 babies get diagnosed with Down syndrome. In India, approximately 23,000 – 29,000 children are born with Down syndrome. About 6000 babies are born with Down syndrome in the USA, which is 1 in 700 children.

Low Fatality Rate 

Because of more awareness and medical advancement, the fatality rate is lower than ever now. In 2015, 27,000 death happened among 5.4 million individuals, compared to 43,000 deaths in 1990.

The life expectancy rate has increased dramatically from 9 years to 50 years- 60 years. But in developing countries, it’s less low because of the poor healthcare facilities.

The overall number of newborns with Down Syndrome is much lower in developed nations compared to the developing ones. The obvious reason is medical advancement.

In developed nations, mothers have access to prenatal screening and genetic counselling, and because of that, most of them choose abortion.

While in developing countries, the lack of these medical facilities led to less abortion, but it results in a higher rate of abandonment of infants and children. Lack of basic healthcare led to a higher mortality rate among children with Down syndrome.

Parental Age Risk factor

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Photo by MART PRODUCTION from Pexels

Mothers aged 35 or younger than 35 years old are more likely to have children (81%) with either Trisomy 21 or Mosaicism as they have children more frequently.

But as the women get older, risk factors are more likely to increase. At age 20, the risk is 1 in 1441, at age 30, the risk is 1 in 959, at age 35, the risk is 1 in 84, at age 40, the risk is 1 in 350, at age 45, the risk is 1 in 30.


Doctors could diagnose the syndrome by a screening test and chronic villus sampling (Prenatal Diagnosis to detect the genetic disorder in the fetus).

Screening tests determine how high or low are the risk of Down syndrome 4in the fetus, while chronic villus sampling confirms if the fetus has the condition.

Employment Scenario

According to research done by NCHPAD (National Center on Health, Physical Activity, and Disability) in 37 states, only 57% of adults with Down syndrome were employed.

These were lower-grade jobs such as fast food and kitchen work, cleaning & janitor workers, florist & landscaping, light assembling line work in factories, and, office mail delivery work even though 69% knew how to use computers.

Genetic or Hereditary?

Trisomy 21 and mosaicism are not hereditary, while some cases of translocation are hereditary.

In trisomy 21 and mosaicism5, random cell division occurs during fetus development, while only one-third of translocation cases are hereditary.


Since there is no cure for Down Syndrome, its impact can be minimized by proper health care and providing the right schooling and life skills for children from an early age.

Some children attend regular schools while children with moderate and severe disorders go to special schools where they get speech, language, learning, physical and other therapies with vocational classes which suit them best.

Many states facilitate free early intervention services from birth to age 3 to guide parents through caring and other important processes. A few adults can attend college.

Here is the encouraging story of S. Ramnath – who works as an agent at HDFC Limited and Chris Nikic – the World’s first athlete with Down Syndrome to clear Ironman

Frequently Asked Questions

1. Can a Down syndrome child look normal?

Numerous individuals with Down syndrome exhibit typical facial characteristics and no other significant birth abnormalities. Refer to the article above to know about such facial features.

2. Can a Down syndrome person have a baby?

A person having Down syndrome can indeed encounter severe difficulties in conceiving. However, Down syndrome-affected women are fertile and capable of having children.

3. Can Down syndrome marry normally?

Who is a medical condition to stand between two people who love? So, yes, you can marry normally if you have Down syndrome. 

The Bottomline

Even though doctors can’t cure Down syndrome, early expert intervention and parents must accelerate their development.

Early schooling (home & special or normal school), physical and speech therapies, and introducing them to different vocational courses can help them lead their lives with less difficulty.

Above all, children diagnosed with this disorder need understanding, love, and equal treatment from the people around them. We hope above mentioned ten facts about Down syndrome will give people a better perception of this condition.

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  1. Thorpe, Jeremy, et al. “Mosaicism in human health and disease.” Annual review of genetics 54 (2020): 487-510. ↩︎
  2. Chellappa, Sarah L., and Daniel Aeschbach. “Sleep and anxiety: From mechanisms to interventions.” Sleep medicine reviews 61 (2022): 101583. ↩︎
  3. Magliano, Dianna J., and Edward J. Boyko. “IDF diabetes atlas.” (2022). ↩︎
  4. Shahrizaila, Nortina, Helmar C. Lehmann, and Satoshi Kuwabara. “Guillain-Barré syndrome.” The lancet 397.10280 (2021): 1214-1228. ↩︎
  5. Popovic, Mina, et al. “Chromosomal mosaicism in human blastocysts: the ultimate diagnostic dilemma.” Human Reproduction Update 26.3 (2020): 313-334. ↩︎

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