What is Down Syndrome (Trisomy 21)? Down syndrome (Trisomy 21) Made Easy
Summary
TLDRDown 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
🧬 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.
🩺 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.
Mindmap
Keywords
💡Down syndrome
💡Chromosome
💡Trisomy
💡Facial features
💡IQ
💡Life expectancy
💡Screening tests
💡Diagnostic tests
💡Mosaic Down syndrome
💡Support and educational programs
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
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