Down’s syndrome

 

 

 

 

English: "This photograph depicts a newbo...

English: “This photograph depicts a newborn with the genetic disorder Down Syndrome, due to the presence of an extra 21st chromosome.” (Photo credit: Wikipedia)

What is Down’s syndrome?

 

 

 

Down syndrome is a genetic condition in which the affected person is born with mental disability and characteristic features.

 

 

 

These characteristic features have been called mongolism with:

 

1. Obliquely set eyes

 

 

 

2. Narrow palpebral fissures

 

 

 

3. Epicanthyl folds

 

 

 

4. Short stubby nose

 

 

 

5. Flattened facies

 

 

 

6. Short stature

 

 

 

7. Generalized muscular hypotonia

 

 

 

8. Dry skin

 

 

 

9. Thin fine hair

 

 

 

10. Underdeveloped genitalia

 

 

 

Most people with Down’s syndrome are not able to look after themselves because of their mental disability.

 

 

 

But many of them have gentle and endearing personalities.

 

 

 

There is no medical cure for this condition.

 

 

 

What causes Down’s syndrome?

 

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Chromosomes are tiny structures in our body cells which can be seen only with a special microscope.

 

They contain the genes which determine the characteristics of a person.

 

 

 

Abnormal person has 23 pairs of matching chromosomes in each cell.

 

Each pair is different and given a number except for the sex chromosomes which are named XY in the male and XX in the female.

 

 

 

A person with Down’s syndrome has an extra chromosome no.21

 

 

 

 

 

What are the Types of Down Syndrome?

 

 

 

There are three genetic variations that can cause Down syndrome:

 

 

 

1.Trisomy 21 is the commonest type in which all the cells have an extra chromosome 21.Here something goes wrong during egg formation in the mother so that the mother has an abnormal egg with extra chromosomes no.21. The child will then get an extra chromosome no.21. The cause of this abnormal egg formation is unknown but occurs more frequency with the mother’s age.

 

 

 

2.Translocation Down syndrome happens when the extra chromosome 21  is attached to another chromosome. During cell division the embryo may get the attached chromosome and so have an extra chromosome no 21 and get Down’s Syndrome.

 

 

 

3.Mosaic Down syndrome is another form of Down’s Syndrome in which only some cells have an extra chromosome 21.

 

 

 

 

 

What are the Risk factors of getting Down’s Syndrome?

 

 

 

Risk factors include:

 

 

 

1.maternal age above 35 years. Most cases of Down’s syndrome are born to women aged 35 and above. The risk of a woman above age 36 conceiving a child with Down syndrome is 1 in 350. The risk increases to 1 in 100 by the age of 40 and to 1 in 25 at the age of 45.

 

 

2.Mothers with one Down syndrome child have a 1 in 100 chance of having another child with Down syndrome.

 

 

 

3.Parents who are known to carry the translocated chromosome for Down syndrome can pass the abnormal gene to their offspring.

 

 

 

 

 

What are the Symptoms of Down’s Syndrome?

 

 

 

Mongolian features:

 

1. distinct flat facial profile

 

 

 

2. Upward slanting eyes

 

 

 

3. Flat nose

 

 

 

4. Protruding tongue

 

 

 

5. Flat back of the head

 

 

 

6. Small statue

 

 

 

7. Poor muscle tone

 

 

 

8. Broad, short hands with short fingers and a single crease in the palm

 

 

 

9. dry skin

 

 

 

10. thin fine hair

 

 

 

Mental retardation

 

1. mental disability

 

 

 

2. unable to look after themselves

 

 

 

Congenital defects:

 

1. congenital heart disease

 

 

 

2. other birth defects

 

 

 

Screening tests are done for all pregnant women above 35 years of age and include:

 

 

 

1.Triple test – is a blood test done for older pregnant mothers above 35 years which measures specific proteins in the mother’s blood. This may indicates the possibility of Down’s Syndrome

 

 

 

2.Nuchal translucency test is an ultrasound scan of the embryo at 10-13 weeks of pregnancy. It measures the width of the spinal cord at the back of the baby’s neck.

 

 

 

If the screening tests suggest a possible high risk of Down syndrome, then the following diagnostic tests may be performed to determine or confirm whether the baby actually has Down syndrome:

 

 

 

1.Amniocentesis. A small amount of the amniotic fluid is obtained through a needle inserted into the mother’s womb after 16 weeks of pregnancy. This fluid contains cells shed from the baby and can be examined to see if the chromosomes are normal.

 

 

 

2.Chorionic Villous Sampling (CVS) involves obtaining some cells from the mother’s placenta to examine the baby’s chromosomes. It is usually done around the 14th week of pregnancy.

 

 

 

3.Percutaneous umbilical blood sampling (PUBS) involves obtaining blood from a vein in the umbilical cord after 18 weeks of pregnancy. The blood cells are examined for chromosomal defects.

 

 

 

Complications of Down’s Syndrome are:

 

 

 

1. Heart defects.

 

 

 

2. Leukemia

 

 

 

3. Infectious diseases such as pneumonia

 

 

 

4. Dementia often appear before age 40

 

 

 

5. intestinal obstruction,

 

 

 

6. thyroid problems,

 

 

 

7. hearing loss

 

 

 

8. poor vision.

 

 

 

 

 

Treatment of Down’s Syndrome:

 

 

 

There is no medical cure for Down syndrome.

 

However, children with Down syndrome do benefit from medical help and early interventions starting in infancy which improve the life expectancy and quality of life.

 

 

 

Prevention of Down’s Syndrome:

 

 

 

Down syndrome cannot be prevented.

 

1. genetic counseling in high risk translocation genetic group before considering pregnancy.

 

 

 

2. Coping and support from a team of doctors, teachers and therapists who can  provide the resources and support to  take better care of your child.

 

 

 

3. Joining a Down Syndrome support group and families who are dealing with the same problem

 

 

 

Prognosis:

 

 

 

1. A better understanding of Down syndrome and early interventions has improved the quality of life of children and adults with Down syndrome.

 

 

 

2. If there are no major complications such as heart disease and leukemia, a person with Down Syndrome may have a slightly shortened life span than a normal person.