Trisomy 18

Trisomy 18

Edwards Syndrome​

By Kathy, Rebecca, and Tasnuva

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• Trisomy 18, or Edwards syndrome is a genetic disorder that includes a combination of birth defects. The term trisomy describes the presence of three chromosomes as opposed to the usual two pairs. Trisomy 18 means that the child has 3 copies of the chromosome numbered 18.

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What is this disorder?

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What are the characteristics and symptoms?​

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A baby with Trisomy 18 may have symptoms such as...​

• Looking thin and frail

• Failure to thrive

• Problems feeding

• Small size, even when delivered full term

• Small head

• Low-set ears​

• Small mouth and jaw

• Shortened breastbone (Sternum)

• Weak cry

• Problems with hearing

• Heart defects

• Can't extend fingers fully

• Arms and legs in a bent position (contracture)

• Feet with a curved shape, known as rocker bottom

• Spina bifida

• Eye problems

• Cleft lip and palate

​...Continued to the next slide

• Slow growth

• Seizures

• High blood pressure

• Kidney problems

• Curvature of the spine (scoliosis)

• In boy babies, testes not descended into the scrotum

• Severe learning problem​

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​Continuation of characteristics and symptoms

​Most babies with trisomy 18 have problems that affect all parts of the body. Heart problems, feeding problems, and infections are what most often lead to the death of the child, and those with Edward's syndrome usually do not make it past their first year of life. If they're fortunate enough to live, the child would most likely not live past their teen years.

Multiple Select

Which of the following are symptoms of Trisomy 18?

• Seizures

• Shortened sternum

• Kidney problems

• Scoliosis

​What causes this disorder?

Trisomy 18 is normally caused by spontaneous genetic mutation that occurs during fertilization. Normally, each egg and sperm cell contains​ 23 chromosomes, when combined during this process they total to 46, or 23 pairs, half from the mother, and half from the father. Sometimes an error occurs when an egg or sperm cell is forming, this error can lead to an extra chromosome 18. When the cell contributes its extra chromosome to the embryo, trisomy 18 results.

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Continuation of "What causes this disorder?"​

​The extra chromosome can come from either the mother or the fathers sperm cell. In some instances, the extra chromosome 18 is attached to another chromosome in the egg or sperm. This is called translocation, and it is the only form of trisomy 18 that can be inhereted. Mosaic trisomy 18 is when an error occurs in cell division after the fertilization process. Those who process this syndrome have both normal cells and the ones with the extra chromosome number 18.

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Trisomy, 3 copies of ​chromosome 18, 47 chromosomes

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​Chromosome Mutation

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Gene Mutation

The genes affected by trisomy 18 are the ones that relate to the baby’s development [Chromosome 18]. These genes change, making the baby look frail and weak, for example: the small mouth and jaw, looking thin and frail, and small head. This is opposed to how the baby normally looks, even if it is delivered at full term. Chromosome 18 likely contains 200 to 300 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body, making it easy to tamper with traits by way of the proteins, creating the trisomy 18 symptoms.

How is it inherited?

Trisomy 18 is not inherited, it is a spontaneous mutation that occurs in about 1 out of 5,000 to 8,000 live births; however, in some instances, the extra chromosome 18 is attached to another chromosome in the egg or sperm, this is called translocation and is the only form of trisomy 18 that can be inherited. Trisomy 18 is a common autosomal chromosomal disorder, it is neither recessive or dominant as it does not occur through genes being passed down.

Trisomy 18 is not incredibly common, the disorder only occurs in about 1 out of every ​6,000-8,000 live births.

How common is this disorder?​

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What portion of the human population is affected by this disorder?

Trisomy 18 usually occurs in 1 out of every 6,000-8,000 births. Parents who already have a child with Trisomy 18 have no more than a 1 percent chance of having another child with Trisomy 18.

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Multiple Choice

Out of how many births does Trisomy 18 occur in?

• 4,000-6,000

• 8,000-11,000

• 5,000-8,000

• 6,000-8,000

Is there a population more at risk?

For women who are under the age of 35, the chance of having a child with Trisomy 18 depends on many factors. However, the chance of having a child with Trisomy 18 increases slightly when women get older. This is because chromosomal abnormalities are more likely to occur in older women.​

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Multiple Choice

The risk of having a child with Trisomy 18 increases as you get older.

• True

• False

How is this disorder diagnosed?

Trisomy 18 can be diagnosed by analyzing the cells in the placenta or the amniotic fluid. An ultrasound can also show a possibility of Trisomy 18. Trisomy 18 can also be diagnosed with a blood sample after the child is born.

Multiple Choice

Can you diagnose Trisomy 18 with an ultrasound?

• Yes

• No

• ...

Trisomy 18 can also be diagnosed with a blood sample after the child is born.

Trisomy 18 can be tested during pregnancy by using fetal ultrasound and checking if the child has a possibility of Trisomy 18.

When is it tested for?

How is it tested for?

What tests are used and what does it show or look for?

During pregnancy, Trisomy 18 can be diagnosed using three different tests. These three tests are amniocentesis, chorionic villus sampling, and screenings. For the amniocentesis test, a doctor will take a sample of amniotic fluid to identify if the child had any potential health conditions. For the chorionic villus sampling, a doctor will take a cell sample from your placenta to look for any genetic conditions.

Multiple Choice

How many tests can be used to diagnose Edwards Syndrome?

• 2

• 4

• 3

• 6

Treatment for children with Trisomy 18 depends on how severe the condition and symptoms are for the child, so treatment is different for every child.

What treatments are available for this disorder and its symptoms?

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• Cardiac treatment

• Psychosocial support

• Orthopedic Treatment

• Assisted feeding​

​Some of the treatments may include:

What is the prognosis?

What is the life expectancy for individuals with this disorder?

The life expectancy for children with Trisomy 18 is very short due to all of the life threatening complications the condition has. Children who survive their first year of life with Trisomy 18 may face some intellectual challenges.

What current research is being done to develop a cure?

Currently there is no cure for Trisomy 18, sinc emost babies born with this disorder don't survive their first days/weeks of life. Doctors are not sure how to prevent the chromosomal error that causes Trisomy 18 . Parents cannot do anything to prevent their children from having Trisomy 18 either. Though efforts have so far failed, many researchers are searching for a cure.

​VIDEO

​https://www.youtube.com/watch?v=9gUiHr3wrhA

Sources

​https://www.stanfordchildrens.org/en/topic/default?id=trisomy-18-and-13-90-P02419

https://www.childrenshospital.org/conditions/trisomy-18-and-13​

https://www.chop.edu/conditions-diseases/trisomy-18-and-13​

https://my.clevelandclinic.org/health/diseases/22172-edwards-syndrome​

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