What is Down Syndrome (Trisomy 21)? Down syndrome (Trisomy 21) Made Easy

Summary

Down syndrome, or trisomy 21, is a genetic disorder caused by an extra chromosome 21. It affects both mental and physical development, with individuals exhibiting varying abilities and distinct facial features. Commonly associated with mild to moderate intellectual disability and speech delays, it occurs in about 1 in 700 births. There are three types: Trisomy 21 (95%), Translocation (3%), and Mosaic (2%). Prenatal detection is possible through screening and diagnostic tests, though no cure exists. Support and educational programs help individuals with Down syndrome and their families.

Takeaways

• 🧬 Down syndrome, or trisomy 21, is a genetic disorder caused by the presence of an extra chromosome 21.
• 👶 Typically, humans have 46 chromosomes, but individuals with Down syndrome have 47 due to the extra chromosome 21.
• 🧠 The extra chromosome affects the development of the body and brain, leading to mental and physical challenges.
• 🌟 People with Down syndrome exhibit a range of abilities and characteristics, with no two individuals being exactly alike.
• 🏥 Down syndrome is the most common chromosomal condition in the United States, occurring in about 1 in 700 births.
• 🔍 There are three types of Down syndrome: Trisomy 21 (95% of cases), Translocation Down syndrome (3%), and Mosaic Down syndrome (2%).
• 🩺 Prenatal tests such as screening and diagnostic tests can help detect Down syndrome during pregnancy.
• 🚫 Screening tests provide risk assessment, while diagnostic tests can confirm a diagnosis but carry more risk.
• 👨‍⚕️ Children with Down syndrome may have associated health issues like hearing loss, heart defects, and sleep apnea.
• 🏫 Support and educational programs are available to help individuals with Down syndrome and their families, focusing on skills development.

Q & A

What is Down syndrome?

Down syndrome, also known as trisomy 21, is a genetic disorder where a person has an extra copy of chromosome 21, which can cause both mental and physical challenges.

How does the presence of an extra chromosome affect a person with Down syndrome?

The extra chromosome 21 changes how the baby's body and brain develop, leading to various mental and physical challenges.

What is the significance of the term 'trisomy' in the context of Down syndrome?

The term 'trisomy' refers to the condition where an individual has three copies of a chromosome instead of the usual two, which is the case with chromosome 21 in Down syndrome.

What are the common facial features associated with Down syndrome?

Common facial features include a flattened face, almond-shaped eyes that slant up, a short neck, small ears, and a tongue that tends to stick out of the mouth.

How does Down syndrome impact a person's cognitive abilities?

People with Down syndrome usually have an IQ in the mildly-to-moderately low range and are slower to speak than other children.

What is the prevalence of Down syndrome in the United States?

Down syndrome occurs in about 1 in every 700 babies born in the United States, with approximately 6,000 babies being born with the condition each year.

What are the three types of Down syndrome?

The three types of Down syndrome are Trisomy 21 (95% of cases), Translocation Down syndrome (3% of cases), and Mosaic Down syndrome (2% of cases).

How do screening tests for Down syndrome work during pregnancy?

Screening tests, such as blood tests and ultrasounds, can indicate whether a pregnancy has a higher or lower chance of having Down syndrome without providing a definitive diagnosis.

What are diagnostic tests, and how do they differ from screening tests?

Diagnostic tests, such as Chorionic villus sampling (CVS), Amniocentesis, and Percutaneous umbilical blood sampling (PUBS), can confirm a Down syndrome diagnosis but are riskier for the mother and developing baby compared to screening tests.

Can the full impact of Down syndrome on a baby be predicted through tests?

Neither screening nor diagnostic tests can predict the full impact of Down syndrome on a baby; the extent of the condition's effects varies from person to person.

What support and educational programs are available for individuals with Down syndrome?

Support and educational programs for individuals with Down syndrome include special education and therapy services that help develop sensory, social, self-help, motor skills, and language and cognitive abilities.

Outlines

00:00

🧬 Understanding Down Syndrome

Down syndrome, or trisomy 21, is a genetic disorder characterized by the presence of an extra chromosome 21. Typically, humans have 46 chromosomes, but individuals with Down syndrome have three copies of chromosome 21. This additional genetic material affects the development of the body and brain, leading to a range of mental and physical challenges. Despite these challenges, people with Down syndrome can lead healthy and fulfilling lives. They often have distinct facial features, such as a flattened face, almond-shaped eyes, and a short neck, among others. The condition is the most common chromosomal disorder in the United States, affecting approximately 1 in every 700 babies born. There are three types of Down syndrome: Trisomy 21 (95% of cases), Translocation Down syndrome (3%), and Mosaic Down syndrome (2%). The latter involves a mixture of cells with three and two copies of chromosome 21.

05:05

🩺 Detecting and Living with Down Syndrome

To detect Down syndrome during pregnancy, two types of tests are available: screening and diagnostic. Screening tests, such as blood tests and ultrasounds, assess the risk of the fetus having Down syndrome without providing a definitive diagnosis. Diagnostic tests, which are conducted after a positive screening, include procedures like chorionic villus sampling, amniocentesis, and percutaneous umbilical blood sampling. These tests analyze the chromosomes to confirm a diagnosis. While there is no cure for Down syndrome, various support and educational programs are available to assist individuals and their families. These programs focus on developing sensory, social, self-help, motor skills, and language and cognitive abilities to enhance the quality of life for those with the condition.

Keywords

💡Down syndrome

Down syndrome, also known as trisomy 21, is a genetic disorder characterized by the presence of an extra chromosome 21. This condition is central to the video's theme, as it discusses the various aspects of this disorder, including its causes, effects, and the types of Down syndrome. The video mentions that Down syndrome affects both mental and physical development, and that individuals with this condition can have distinct facial features and varying abilities.

💡Chromosome

Chromosomes are structures made up of DNA and proteins that are found in the nucleus of cells. They carry genetic information essential for the development and functioning of an organism. In the context of the video, the focus is on chromosome 21, which, when present in an extra copy, leads to Down syndrome. The video explains that typically, a baby is born with 46 chromosomes, but babies with Down syndrome have an extra copy of chromosome 21.

💡Trisomy

Trisomy is a medical term used to describe a condition where an individual has three copies of a particular chromosome, instead of the usual two. The video uses 'trisomy' to explain the genetic basis of Down syndrome, specifically 'Trisomy 21,' which is the presence of three copies of chromosome 21. This term is crucial for understanding the genetic cause of the disorder.

💡Facial features

The video highlights that children and adults with Down syndrome often have distinct facial features, which can include a flattened face, almond-shaped eyes, a short neck, and small ears. These features are part of the physical characteristics associated with the condition and are used to illustrate some of the common physical traits that may be observed in individuals with Down syndrome.

💡IQ

IQ, or Intelligence Quotient, is a measure of cognitive abilities. The video mentions that people with Down syndrome usually have an IQ in the mildly-to-moderately low range, which is an important aspect of understanding the cognitive challenges that may be associated with the condition. This information helps to contextualize the learning and developmental needs of individuals with Down syndrome.

💡Life expectancy

Life expectancy refers to the average number of years a person is expected to live. The video notes that some disabilities associated with Down syndrome can shorten life expectancy. This concept is significant as it touches upon the health challenges and long-term implications of living with Down syndrome.

💡Screening tests

Screening tests are non-invasive procedures used to determine the likelihood of a condition, such as Down syndrome, being present in a fetus. The video explains that these tests can indicate whether a pregnancy has a higher or lower chance of having Down syndrome without providing a definitive diagnosis. Examples of screening tests mentioned include blood tests and ultrasounds.

💡Diagnostic tests

Diagnostic tests are more invasive procedures that can provide a definitive diagnosis. In the context of the video, diagnostic tests such as Chorionic villus sampling (CVS), Amniocentesis, and Percutaneous umbilical blood sampling (PUBS) are mentioned. These tests are used to confirm a Down syndrome diagnosis by examining placental material, amniotic fluid, or blood from the umbilical cord for chromosomal abnormalities.

💡Mosaic Down syndrome

Mosaic Down syndrome is a type of Down syndrome where some cells have the typical two copies of chromosome 21, while others have three. The video explains that this type affects about 2% of people with Down syndrome and that it may result in a less severe presentation of the condition due to the presence of cells with a typical number of chromosomes.

💡Support and educational programs

The video emphasizes the importance of support and educational programs for individuals with Down syndrome and their families. These programs, which may include special education and therapy, aim to help children with Down syndrome develop skills such as sensory, social, self-help, motor, language, and cognitive abilities. This keyword highlights the resources available to enhance the quality of life for those with the condition.

Highlights

Down syndrome is a genetic disorder caused by the presence of an extra chromosome 21.

Chromosomes are genetic 'packages' that determine the formation and function of a baby's body.

Typically, humans have 46 chromosomes, but individuals with Down syndrome have 47 due to the extra chromosome 21.

The condition is medically referred to as 'trisomy' when there are three copies of a chromosome.

Down syndrome can lead to both mental and physical challenges.

Individuals with Down syndrome exhibit a range of abilities, and no two are exactly alike.

Down syndrome is associated with a reduced life expectancy and lifelong disabilities.

People with Down syndrome can lead healthy and fulfilling lives with appropriate support.

Individuals typically have an IQ in the mildly-to-moderately low range and may speak more slowly.

Facial features of Down syndrome often include a flattened face, almond-shaped eyes, and a short neck.

Down syndrome is the most common chromosomal condition in the United States, affecting about 1 in 700 babies.

There are three types of Down syndrome: Trisomy 21, Translocation, and Mosaic.

Trisomy 21 is the most common form, accounting for approximately 95% of cases.

Translocation Down syndrome occurs when chromosome 21 is attached to another chromosome.

Mosaic Down syndrome is rarer, with some cells having an extra chromosome 21 and others not.

Screening tests can indicate the likelihood of Down syndrome but do not provide a definitive diagnosis.

Diagnostic tests, such as CVS, Amniocentesis, and PUBS, can confirm a diagnosis but carry risks.

Down syndrome cannot be cured, but support and educational programs can significantly aid development.

Support programs help individuals with Down syndrome develop sensory, social, self-help, motor, and language skills.

Transcripts

Down syndrome, also known as trisomy 21, is  

a genetic disorder in which a  person has extra chromosome. 

Chromosomes are small  “packages” of genes in the body. 

They determine how a baby’s  body forms and functions as  

it grows during pregnancy and after birth. Typically, a baby is born with 46 chromosomes. 

Babies with Down syndrome have an extra copy  of one of these chromosomes, chromosome 21. 

A medical term for having an extra  copy of a chromosome is ‘trisomy.’  

Therefore, Down syndrome is  also referred to as Trisomy 21. 

This extra copy changes how the baby’s body  and brain develop, which can cause both mental  

and physical challenges for the baby. Even though people with Down syndrome  

might act and look similar, each  person has different abilities. 

Many of the disabilities are lifelong,  and they can also shorten life expectancy.  

However, people with Down syndrome  can live healthy and fulfilling lives. 

People with Down syndrome usually have  an IQ in the mildly-to-moderately low  

range and are slower to speak than other children. 

Children and adults with Down syndrome have  distinct facial features. Though not all people  

with Down syndrome have the same features,  some of the more common features include: 

A flattened face, especially  the bridge of the nose 

Almond-shaped eyes that slant up 

A short neck Small ears 

A tongue that tends to stick out of the mouth 

Tiny white spots on the iris  (colored part) of the eye 

Small hands and feet 

A single line across the palm  of the hand (palmar crease) 

Small pinky fingers that  sometimes curve toward the thumb 

Poor muscle tone or loose joints Shorter in height as children and adults 

Down syndrome remains the most common chromosomal  condition diagnosed in the United States. 

Each year, about 6,000 babies born in  the United States have Down syndrome. 

This means that Down syndrome occurs  in about 1 in every 700 babies. 

There are three types of Down syndrome. 1- Trisomy 21: 

About 95% of people with Down  syndrome have Trisomy 21.  

With this type of Down syndrome, each cell in  the body has 3 separate copies of chromosome  

21 instead of the usual 2 copies. 2- Translocation Down syndrome: 

This type accounts for about 3%  of people with Down syndrome.  

This occurs when an extra part or a  whole extra chromosome 21 is present,  

but it is attached or “trans-located” to  a different chromosome rather than being  

a separate chromosome 21. 3- Mosaic Down syndrome: 

This type affects about 2% of  the people with Down syndrome. 

Mosaic means mixture or combination. 

For children with mosaic Down syndrome, some  of their cells have 3 copies of chromosome 21,  

but other cells have the typical  two copies of chromosome 21. 

Children with mosaic Down syndrome  may have the same features as other  

children with Down syndrome. However, they may have fewer  

features of the condition due to the presence of  some cells with a typical number of chromosomes.

There are two basic types of tests available  to detect Down syndrome during pregnancy:  

screening tests and diagnostic tests. A screening test can tell a woman and  

her healthcare provider whether her pregnancy has  a lower or higher chance of having Down syndrome. 

Screening tests do not provide an  absolute diagnosis, but they are  

safer for the mother and the developing baby. Diagnostic tests can typically detect whether  

or not a baby will have Down syndrome, but they  can be riskier for the mother and developing baby. 

Neither screening nor diagnostic tests can predict  

the full impact of Down syndrome  on a baby; no one can predict this.

Screening tests often include a combination of a  blood test, which measures the amount of various  

substances in the mother’s blood (e.g., MS-AFP,  Triple Screen, Quad-screen), and an ultrasound,  

which creates a picture of the baby. During an ultrasound, one of the  

things the technician looks at is  the fluid behind the baby’s neck. 

Extra fluid in this region could  indicate a genetic problem. 

These screening tests can help determine  the baby’s risk of Down syndrome.

Diagnostic tests are usually performed  after a positive screening test in order  

to confirm a Down syndrome diagnosis. Types of diagnostic tests include: 

Chorionic villus sampling (CVS)—examines  material from the placenta 

Amniocentesis—examines the amniotic fluid 

Percutaneous umbilical blood sampling  (PUBS)—examines blood from the umbilical cord 

These tests look for changes in the chromosomes  that would indicate a Down syndrome diagnosis. 

Some people with Down syndrome might have one  

or more major birth defects  or other medical problems. 

Some of these are listed below: Hearing loss 

Obstructive sleep apnea Ear infections 

Eye diseases Heart defects present at birth 

There’s no cure for Down syndrome,  but there’s a wide variety of support  

and educational programs that can help both  people with the condition and their families. 

In these programs, special education teachers  and therapists will help your child learn: 

sensory skills social skills 

self-help skills motor skills 

language and cognitive abilities