The news that their child suffers from trisomy 18 is a severe blow of fate for parents-to-be. Many babies with this diagnosis die during pregnancy or within a few days after giving birth. However, some of the small patients also have a life expectancy of a few years. We answer the most important questions about Edwards Syndrome.
- Our genetic material (DNA) is twisted into chromosomes in the cell nucleus. Maldistributions of these chromosomes such as trisomy 18 can occur during cell division, for example.
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Trisomy 18, also known as Edwards syndrome, is a chromosomal disorder that usually leads to serious impairments and organ defects. The majority of babies with triple chromosome 18 die in the womb or shortly after birth.
In fetuses with trisomy 18, development problems are usually noticed during the preventive examinations during pregnancy: They grow more slowly and their head circumference is too small. Further examinations before the birth (prenatal diagnosis) enable an almost certain determination of the syndrome if necessary.
Down syndrome: living with trisomy 21
Little Julia's parents knew early on in pregnancy that their little girl had the chromosomal disorder trisomy 21, also known as Down's syndrome. You made a conscious decision to have the child – and have not regretted this decision.
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What is trisomy 18?
Trisomy 18, just like trisomy 21 ("Down syndrome"), is a so-called chromosomal abnormality. This means that an error has occurred in the composition of the chromosomes in which our genetic material is organized in the cell nucleus. This can happen during cell division, for example. Another possibility is that one of the germ cells – i.e. sperm or egg cell – already contained an extra chromosome.
Depending on whether the entire chromosome 18 is present a third time or only parts of it and whether all child cells are affected by the maldistribution (free trisomy 18), doctors differentiate between different types of trisomy 18. This also depends on how severe the disabilities are Babies are.
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If chromosome 18 is present three times instead of two, experts speak of trisomy 18, which is also known as Edwards syndrome after its discoverer.
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How many children have trisomy 18?
By the 12th week of pregnancy, about 1 in 2,000 fetuses has trisomy 18. Because many of them die during pregnancy, this rate drops to around one or two affected babies per 6,000 live births.
This makes trisomy 18 very rare, but still the second most common trisomy after Down's syndrome. Girls are born with trisomy 18 three times as often as boys. In addition, the risk is clearly related to the age of the mother: the older a woman, the higher the probability of trisomies in the baby.
Causes and Risk Factors for Edwards Syndrome
In addition to the relationship with the mother's age, there are little known risk factors for the development of trisomies such as Edwards syndrome. The risk of expecting another child with trisomy 18 is therefore only marginally increased after diagnosis.
The only exception: in the very rare translocation trisomy 18, a healthy parent can act as a "silent" carrier. In this case, one section of that chromosome is attached to another. In the person himself, this peculiarity may remain symptom-free (balanced translocation), but during germ cell formation an unbalanced translocation can occur, resulting in the typical appearance of a trisomy.
Trisomy 18 cannot be treated causally
Because the causes mentioned cannot be treated, there is no causal therapy for Edwards syndrome. However, through operations and other treatment options, doctors can alleviate a large number of symptoms – sometimes while still in the mother's womb – by correcting, for example, heart defects or external features such as cleft lip and palate. A nasogastric tube is often necessary, and physiotherapy can also be used as a symptomatic therapeutic measure.
Symptoms and Features of Trisomy 18
During the ultrasound examinations as part of prenatal care, unborn babies with trisomy 18 show a number of abnormalities. These include:
- Heart defect
- below average size and weight
- few child movements
- a small head size, triangular forehead (strawberry head) and sweeping back of the head
- small mouth and chin region and mouth opening
- Malformations of the central nervous system such as hydrocephalus (water head)
- too much fluid in the neck area
- Organ malformations in the abdomen, for example umbilical hernia
- Malformations of the urinary and digestive tract
- missing spoke (forearm bone)
- large amount of amniotic fluid
- single instead of paired umbilical artery
Heart defects such as the ventricular septal defect ("hole in the heart") are very common at 80 percent.
A total of around 150 such abnormalities have been documented, so the appearance of patients with trisomy 18 is extremely diverse. After the birth you can – but don't have to! – The following additional features and symptoms or a combination thereof occur:
- strikingly shaped, deep-seated auricles
- Hearing impairment
- Malformations of the eyes
- flat chest, short sternum
- mental impairments
- missing or malformed thumb
- The thumb and little finger cross the remaining fingers
- Four-finger furrow
- Club or flat feet
Children with trisomy 18 also learn to sit, crawl and walk later than their peers. They usually have massive problems with language expression.
Diagnosis: diagnose trisomy 18
The presence of typical features may lead to the suspected diagnosis of trisomy 18 by the treating gynecologist. A blood test on the mother can reveal whether the risk of trisomies is generally increased, but it does not provide any reliable result.
Invasive methods such as amniocentesis are therefore necessary to determine Edwards syndrome during pregnancy with almost no doubt. However, they carry the risk of causing a miscarriage.
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For a chromosome analysis, sufficient child genetic material must first be obtained.
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After delivery, trisomy 18 can be safely diagnosed by examining the child's blood. Here, experts also recognize the form of the trisomy.
Life expectancy in trisomy 18: a few days to a few years
The life of many babies with trisomy 18 ends in (early) pregnancy, sometimes unnoticed by the mother. If this period is survived, the average life expectancy after birth is only a few days.
The exact prognosis, however, depends very much on the type of trisomy, how pronounced the organ malformations and other physical impairments are, and how well they can be treated. With targeted therapeutic measures, Edwards syndrome patients can live to be a few years old.
On average, female babies have a significantly better prognosis than male babies: around every second girl reaches their first birthday, but only around every tenth boy. 15 percent of girls survive the age of five.
Myths that even medical professionals are exposed to
