Pediatrics

Trisomy 18

definition

Trisomy 18, also known as Edwards syndrome, is a serious gene mutation. Chromosome 18 occurs three times in the body cells instead of the usual two.
After trisomy 21, also known as Down syndrome, trisomy 18 is the second most common occurrence: on average, around 1 in 6,000 births is affected.

Edwards syndrome is a syndrome with severe symptoms and a very poor prognosis.
About 90% of the affected fetuses die before birth.

causes

Trisomy 18 is a so-called chromosome aberration in which chromosome 18 is defective in the body's cells.
Normally, every cell in the body has 23 pairs of chromosomes, each with two chromosomes - also called a double set of chromosomes.
One of the chromosomes comes from the father, one from the mother.
This is due to the fact that the egg cell and the sperm cell each only have a so-called half set of chromosomes.
If the two cells fuse, each of the 23 chromosomes is present twice.

There are several ways at which point in this process errors appear that lead to a third 18th chromosome:
For example, an incorrect division of the chromosomes may already have occurred during the development of the mother's egg cell.
However, it is also conceivable that there was a mistake in the development of the father's sperm cells.
However, the error can also only occur after the sperm and egg cells have merged with further cell divisions.

Depending on when the error leading to the trisomy occurred, there are 3 different types of trisomy 18: the free trisomy, the mosaic trisomy and the translocation trisomy.

The likelihood of trisomy 18 increases with the age of the mother during pregnancy. However, young mothers can also have children with trisomy 18. The mother's age should be assessed as a risk factor and should not be categorically associated with a trisomy.

diagnosis

If the attending gynecologist notices typical irregularities in the unborn fetus during an ultrasound examination, these changes can be used to suspect trisomy 18.
A blood test can then be carried out on the mother.
If certain blood values in the mother are elevated, this may indicate an increased likelihood of chromosomal aberrations.

Recently, a specific analysis for trisomies can also be carried out using a blood test of the mother, because fragments of children's DNA can also be found in the mother's blood. There are three tests available: the panorama test, harmony test or prenatal test. Nevertheless, it must be said that a trisomy detection based on the mother's blood does not provide 100% certainty. The test can be both false-negative and false-positive.

In order to be able to make a reliable diagnosis, invasive examinations are therefore necessary.
However, the risks of these examinations should not be underestimated and, in the worst case, can lead to a miscarriage. A tissue sample is taken from the mother cake or the amniotic fluid in order to examine the child's cells in the laboratory for a possible trisomy.

Find out more about the diagnostic options at: Prenatal test

I recognize trisomy 18 by these symptoms

Edwards syndrome is characterized by a complex of diverse malformations and disabilities. These can vary in severity and need not all occur in every affected infant.

A so-called flexion contracture of the fingers is typical: the fingers are bent and held in a convulsive manner. The little finger and index finger are cramped over the middle and ring fingers.
Also typical is a small size and low birth weight of the newborn, as well as malformations in the head and face area.
These include the following abnormalities:

so-called faun ears. Ears that start low on the face and are dysmorphic in shape towards the top.
An elongated, narrow head with a large back of the head.
Cleft lip and palate.
A noticeably small chin set back, a small mouth.
Only a narrow gap between the upper and lower eyelids.
A high and broad forehead.

Furthermore, there are often organ malformations.
Mainly heart defects, so-called diaphragmatic hernias, kidney malformations or malformations of the lower urinary tract occur.

The main cardiac defects are ventricular septal defects, atrial septal defects or the Fallot tetralogy.

So-called rocker feet often appear on the lower extremities. This is a strong outward curvature of the sole of the foot, which is reminiscent of the shape of a cradle. In the chest area, the breastbone (sternum) is often very short in relation to the body.
There are also diverse and severe intellectual disabilities.

Also read: Trisomy 18 in the unborn child

therapy

Edwards syndrome cannot be cured these days.
Specifically, this means that you can only treat the symptoms that occur, but cannot prevent them from occurring.

The therapy depends on the malformations and symptoms that have occurred. Possible therapies are, for example, the operation of a heart defect, ventilation in the event of insufficient lung development, or feeding via tube if there are problems with eating.
The treatments try to improve the quality of life of the patient as much as possible and to replace the organ functions as far as possible.

forecast

Unfortunately, the prognosis for trisomy 18 is very poor. About 90% of the affected fetuses die during pregnancy in the womb and are not born alive.
Unfortunately, the mortality of newborn babies is also extremely high.
On average, only about 5% of infants with the disease reach an age of over 12 months.
On average, the live-born infants die after a lifespan of 4 days. Statistically speaking, girls with trisomy 18 have a higher life expectancy than boys with the disease. Unfortunately, trisomy 18 cannot be healed today.

Course of disease

Trisomy 18 is a so-called chromosomal aberration that leads to marked deviations from normal development during the development of the fetus in the womb. It is difficult to generalize as a variety of developmental disorders and resulting disabilities can occur in Edwards Syndrome. Typical changes include major changes in the shape of the face and skull, posture abnormalities in the hands and organic abnormalities.

The great majority of the diseased fetuses die in the womb and are not born alive. Unfortunately, the prognosis for live-born infants is also very poor due to severe organic development and a lack of healing.

How contagious is that?

Trisomy 18 is not an infection, but a random gene mutation.
This gene mutation is not triggered by viruses or bacteria and is in no way contagious.

Infection cannot occur through contact with the child concerned or through contact with the child's parents or siblings.
Infection through food or other products is also not possible.