Down syndrome is a chromosomal condition caused by an extra chromosome 21 due to a chromosomal mistake during cell division.
Down syndrome can have an impact on a person’s cognitive abilities and physical growth, as well as cause developmental differences and an increased risk of certain health issues.
A range of screenings and tests can be used by healthcare providers to diagnose Down syndrome before or after birth.
Down syndrome affects about 1 out of every 700 newborns born.
This post goes through the causes and contributing factors of Down syndrome, as well as the symptoms, diagnosis, and types of Down syndrome, as well as whether or not the condition is inherited or linked to autism.
What is it?
Down syndrome is a genetic condition that develops when a certain chromosome, chromosome 21, has an extra copy. The additional chromosome can have an impact on a person’s appearance, intelligence, and overall development. It also raises the risk of certain health issues.
Causes
Down syndrome is caused by a variety of reasons, although it is more common among older pregnant people. If a pregnant woman is over the age of 35, there is a greater likelihood of miscarriage.
At the age of 25, a pregnant woman has a 1 in 1,250 chance of having a child with Down syndrome. At the age of 40, the risk is around 1 in 100.
Genes, which have a distinct code or set of instructions for generating cells, are found in every cell in the body. These genes are found in the nucleus of the cell, within chromosomes. Each cell has 46 chromosomes, 23 inherited from the mother and 23 inherited from the father.
Down syndrome is caused by an additional full or partial copy of chromosome 21 in some or all of a person’s cells.
Is Down syndrome a hereditary condition?
Down syndrome is not usually hereditary and does not run in families. Though Down syndrome is caused by genetic flaws, it is most commonly caused by faults that occur when the genetic information that makes a child first unites and copies between a sperm and an egg.
Genetics may play a role in Down syndrome. In rare circumstances, there may be a link between the parents of a person with translocation Down syndrome and their chances of having more children with Down syndrome.
According to the Genetic and Rare Diseases Information Center, if one of the parents has a genetic rearrangement termed a balanced translocation, there may be an increased likelihood of Down syndrome in future pregnancies in the parents of a child with Down syndrome due to translocation. This does not, however, happen in every incidence of translocation Down syndrome.
Characteristics
Down syndrome is characterized by different physical characteristics, distinctive health difficulties, and changes in cognitive development.
Physical characteristics
The following are some of the most prevalent physical traits of Down syndrome:
- a flat nasal bridge
- single, deep creases across the center of the palms
- a protruding tongue
- small hands and feet
- eyes that slant upward
- skin folds on the inner corner of the upper eyelid
- white spots on the iris
- low muscle tone
- small stature and a short neck
Developmental delays
The cognitive development profiles of people with Down syndrome usually indicate mild to severe intellectual disability. Cognitive growth and intellectual capacity, on the other hand, are highly variable.
Learning difficulties are common in people with Down syndrome, resulting in developmental delays. Down syndrome is characterized by a distinct set of cognitive and behavioral characteristics. These are different from what is found in children who are ordinarily developing and children who have various causes of intellectual disability.
Down syndrome children frequently miss developmental milestones compared to their classmates. It’s possible that they’ll take a long time to sit, turn over, and stand.
Coordination and fine motor skills may also be affected (movements using small muscles in the hands and wrists). These abilities can take longer to develop after a kid has mastered gross motor skills, which entail whole-body movement.
It’s possible that learning to speak and understand a language will take longer than intended. With that stated, many of these milestones are eventually reached by people with Down syndrome.
People with Down syndrome may also experience the following symptoms:
- impulsive behavior
- a tendency to make poor judgments
- difficulties with attention
Most people with Down syndrome can go to school and be productive members of society if they are engaged and receive regular therapy.
Health issues
General health issues can sometimes impair any organ system or physiological function. A congenital cardiac abnormality affects about 40–60% of people with Down syndrome.
There’s also a greater chance of:
- seizures
- vision disorders such as cataracts
- decreased muscle tone
- congenital hypothyroidism
- hearing loss
Children with Down syndrome are also more likely to develop some infections, such as:
- tonsillitis
- pneumonia
- respiratory infections
- middle ear infections
Hardening of the arteries, diabetic retinopathy, and most types of cancer appear to be at a decreased risk.
Diagnosis
People who are more likely to have a child with Down syndrome may be subjected to screening and diagnostic examinations.
Doctors can do two different types of screening tests.
Prenatal screenings can help determine the likelihood of having a child with Down syndrome and justify further testing, but they do not diagnose the condition.
Diagnostic testing can determine whether or not a fetus will be born with the condition, as well as identify certain anomalies.
Screening tests
People in their 30s and 35s may be subjected to genetic tests during pregnancy due to the increased risk of having a child with Down syndrome.
These tests are fully elective, and not everyone who is pregnant will opt for genetic screening.
There are a number of screening tests available, including:
- Cell-free DNA: This is a blood test that looks for fetal DNA in the blood of a pregnant woman.
- Genetic ultrasound: Doctors combine a thorough ultrasound with blood test data at 18–20 weeks.
- Nuchal translucency testing: An ultrasound can be used to quantify the clear space in the folds of tissue behind the neck of a developing fetus at 11–14 weeks.
- Triple screen or quadruple screen: This test measures the amounts of several chemicals in a pregnant woman’s blood at 15–18 weeks.
- Integrated screen: This combines blood and screening test results from the first trimester, with or without nuchal translucency, with quadruple screening data from the second trimester.
Screening tests can’t tell you if you have Down syndrome.
Screening is a less invasive and less expensive method of determining whether doctors should conduct additional diagnostic testing.
Diagnostic tests
When it comes to recognizing Down syndrome, diagnostic testing are more accurate.
Such tests are normally carried out by a medical practitioner within the uterus.
Diagnostic tests, on the other hand, can increase the risk of:
- preterm labor
- fetal injury
- miscarriage
Diagnostic tests include:
- Percutaneous umbilical blood sampling: A needle may be inserted into the abdomen after 20 weeks to take a small sample of blood from the umbilical cord for analysis.
- Amniocentesis: A doctor may put a needle into the abdomen at 14–18 weeks to obtain a little volume of amniotic fluid for testing.
- Chorionic villus sampling: A doctor may extract a tiny sample of placenta for analysis at 9–11 weeks using a needle placed into the cervix or abdomen.
After a baby is born, a healthcare expert can identify Down syndrome by looking at their:
- tissue
- blood
- physical characteristics
Treatment
Down syndrome does not have a specific treatment. People with the condition, like everyone else, will be treated for whatever health people they may have.
Additional health screening for concerns common to people with the condition may be recommended by healthcare experts.
Early intervention with specialized programs, according to the National Institute of Child Health and Human Development, can help a person maximize their potential and prepare to play an active role in the community. Early intervention may assist people with Down syndrome have better results.
Working with a group of specialists can provide the child with stimulus and encouragement as they grow. This can include a variety of specialists from many fields who can assist the person in their development. These experts could include:
- special educators
- occupational therapists
- social workers
- physicians
- physical therapists
- speech therapists
Children with specific learning and developmental issues may qualify for educational assistance at a public or specialized school.
Children with Down syndrome are entitled to an educational environment that is appropriate for their requirements, with additional support to help them integrate and progress.
Some children will have an Individualized Education Program (IEP), which will be supported by a variety of specialists.
Types
Down syndrome exists in a range of types:
- Trisomy 21: This is the most prevalent kind, accounting for around 95% of all cases. It occurs when a person’s people have 47 chromosomes instead of 46. Trisomy 21 is caused by a nondisjunction mistake in cell division. A sperm or egg cell with this mistake has an extra copy of chromosome 21 before or after fertilization.
- Mosaic Down syndrome: This kind is found in roughly 2% of Down syndrome people. Some of the children’s chromosomes will have a third copy of chromosome 21, while others will have two copies. Depending on the number of cells with 2 or 3 copies of chromosome 21, children have fewer characteristics of the condition.
- Translocation Down syndrome: This accounts for around 3% of all Down syndrome instances. During cell division, a piece of chromosome 21 breaks off and joins to another chromosome, generally chromosome 14. Some Down syndrome causes are caused by the presence of this additional chromosome 21 segment. A person who has a translocation does not have any distinguishing physical characteristics, but they are more likely to have a child who has an additional chromosome 21.
Autism vs. Down syndrome
Down syndrome and autism spectrum disorder are two disorders that might cause a person’s cognitive abilities. There are several significant variances between these conditions.
Unlike Down syndrome, there are no distinguishing physical traits that can be used to identify someone with autism.
Down syndrome is a hereditary condition caused by mutations in the genes. Autism is a neurological condition, and the cause of the disorder is unknown.
Both illnesses can cause speech or learning problems when compared to a typical child of a comparable age, and how this manifests itself varies depending on the condition and individual.
Neither condition has a cure. Most people will employ a variety of treatment and therapy techniques to aid in the management of their condition or the improvement of important areas of their lives.
Outlook
Many tasks that other people can do can be done by a person with Down syndrome. Children may take longer to learn basic abilities like walking and talking, but with early stimulation and treatment, they can develop at their own speed and attend school.
With Down syndrome, people can work and live semi-independently depending on how the condition affects them.
Friendships and relationships are essential for people with Down syndrome. Some will live with a companion or marry and enjoy a self-sufficient existence.
According to the Centers for Disease Control and Prevention (CDC), a person with Down syndrome’s life expectancy has grown dramatically due to current advances in medicine and therapy. In 1960, the average lifespan of a person with Down syndrome was ten years. In 2007, the average lifespan of a person with Down syndrome was 47 years.
Due to current developments in healthcare, early therapies, and successfully controlling congenital concerns such as heart disorders, a person born with Down syndrome today has the highest chance of living a long and fulfilling life.
Conclusion
Down syndrome is caused by a chromosome 21 abnormality. This mistake gets copied into the genes, resulting in a collection of Down syndrome-like traits. Physical traits, developmental disabilities, and the risks of various health concerns are also factors to consider.
While Down syndrome has no cure, early intervention can help a child develop and thrive at their own speed. People with Down syndrome now have a better outlook than ever before because to modern developments in healthcare and therapy, which is likely to continue as additional medical advances are made.
Sources:
- https://www.genome.gov/Genetic-Disorders/Down-Syndrome
- https://www.ncbi.nlm.nih.gov/books/NBK526016/
- https://www.cdc.gov/ncbddd/birthdefects/downsyndrome/data.html
- https://www.down-syndrome.org/en-gb/about-down-syndrome/development
- https://www.medicalnewstoday.com/articles/145554
- https://rarediseases.info.nih.gov/diseases/10247/down-syndrome
- https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html
- https://www.nichd.nih.gov/health/topics/down/conditioninfo/diagnosis
- https://www.ucsfhealth.org/education/prenatal-testing-for-down-syndrome
- https://www.stanfordchildrens.org/en/topic/default?id=pregnancy-over-age-30-90-P02481
- https://www.nichd.nih.gov/health/topics/down/conditioninfo/Pages/treatments.aspx
