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Triosomy 21 : Down's Syndrome

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14 Apr 2022

Abstract :

Down’s syndrome is the most common chromosomal abnormality which occurs due to an increased number of chromosomes or part of chromosomes, this was identified by Victorian physician Dr.John Langdon Down in 1866. Extra copies or parts of chromosomes cause problems in the development of the brain and physical features. Down’s syndrome is usually suspected at birth and Genetic testing is done to verify the presence of the disorder. There are several therapies that might help a child to lead a better life.

Down’s syndrome is a genetic disorder that is a lifelong condition that develops when a baby is still in the womb. Down’s syndrome affects a baby’s normal physical development and causes mild or moderate learning difficulties. One in every 700 babies is born with Down’s syndrome.


History :

The Victorian physician Dr. John Langdon Down, 1866 identified a specific group of patients whose characteristics were upward slanting eyes flattening of the back of the head, and poorly controlled fissured tongue. Nobody had identified this group of people previously and for the next twenty years, these groups of people were known as “Mongolian “now referred to as people with down’s syndrome.

In 1962 nineteen international experts including his grandson, Norman wrote jointly suggesting the lancet change the name to Down’s syndrome. At the request of the people of the Republic of Mongolia, the world health organization adopted the name. In 1965 Down’s syndrome was universally accepted.


Mechanism :

In all cases of reproduction, both parents pass their genes on to their children. These genes are carried in chromosomes. When the baby’s cells develop, each cell is supposed to receive 23 pairs of chromosomes, for 46 chromosomes total. Half of the chromosomes are from the mother, and half are from the father.

In children with Down syndrome, one of the chromosomes doesn’t separate properly. The baby ends up with three copies, or an extra partial copy, of chromosome 21, instead of two. This extra chromosome causes problems in the brain and physical features develop.

There are three types of Down syndrome:

Trisomy 21: Trisomy 21 means there’s an extra copy of chromosome 21 in every cell. This is the most common form of Down syndrome.

Mosaicism: Mosaicism occurs when a child is born with an extra chromosome in some but not all of their cells. People with mosaic Down syndrome tend to have fewer symptoms than those with trisomy 21.

Translocation: In this type of Down syndrome, children have only an extra part of chromosome 21. There are 46 total chromosomes. However, one of them has an extra piece of chromosome 21 attached.


Diagnosis :

If a woman is over 35, and the baby’s father is over 40, or there’s a family history of Down syndrome, you may want to get an evaluation.

First trimester: An ultrasound evaluation and blood tests can look for Down syndrome in your fetus. These tests have a higher false-positive rate than tests done at later pregnancy stages. If results aren’t normal, your doctor may follow up with an amniocentesis after your 15th week of pregnancy.

Second trimester: An ultrasound and quadruple marker screen (QMS) test can help identity Down syndrome and other defects in the brain and spinal cord. This test is done between 15 and 20 weeks of pregnancy.

Tests at birth

· perform a physical examination of the baby

· order a blood test called a karyotype to confirm Down syndrome


Symptoms :

Down syndrome can have many effects, and it’s very different for each person. Some will grow up to live almost entirely on their own, while others will need more help taking care of themselves.


Physical Symptoms:

  • Eyes shaped like almonds

  • Flatter faces, especially the nose

  • Small ears, which may fold over a bit at the top

  • Tiny white spots in the colored part of their eyes

  • A tongue that sticks out of the mouth

  • Short fingers

  • Low muscle tone

  • Loose joints

Mental Symptoms

  • Down syndrome also affects a person’s ability to think, reason, understand, and be social. The effects range from mild to moderate. Children with Down syndrome often take longer to reach important goals like crawling, walking, and talking. As they get older, it may take more time before they get dressed and use the toilet on their own. And in school, they may need extra help with things like learning to read and write.

  • Some also have problems with behavior – they may not pay attention well, or they can be obsessive about some things. That’s because it’s harder for them to control their impulses, relate to others, and manage their feelings when they get frustrated.


Health Conditions

  • Hearing loss

  • Heart problems.

  • Problems seeing.

  • Infections

  • Blood conditions, such as anemia, where you have low iron. It’s not as common, but they also have a higher chance of getting leukemia, a type of blood cancer.

  • Dementia. This is an illness where you lose memory and mental skills.

Therapies :

A variety of therapies can be used in early intervention programs and throughout a person's life to promote the greatest possible development, independence, and productivity. Some of these therapies are listed below.

  • Physical therapy includes activities and exercises that help build motor skills, increase muscle strength, and improve posture and balance.

  • Speech-language therapy can help children with Down syndrome improve their communication skills and use language more effectively.

  • Occupational therapy helps find ways to adjust everyday tasks and conditions to match a person's needs and abilities.

Several other therapies can also help such as music therapy, behavior therapy


Conclusion :

Down’s syndrome is a condition in which there is the excess genetic material. This genetic addition, which is in fact an excess no.21 chromosome (all or part of it, in all or part of the body cells), causes physical and mental disabilities connected with the syndrome.

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Rajvi Sheth

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