Edwards Syndrome (Trisomy 18): What You Need to Know

What Is Edwards Syndrome (Trisomy 18)?

The condition known as Edwards syndrome, also called trisomy 18 syndrome, happens when an individual has three copies of chromosome (a tiny thread-like part inside cells that carries information about how the body grows and works) 18 instead of the usual two.

Because of this extra genetic material (the information in our cells that decides how our body looks and functions), many parts of the body develop differently than expected. Organs, limbs, and the brain can all be affected.

The word “trisomy” itself means “three bodies” (tri = three; soma = body), so trisomy 18 literally refers to three copies of the 18th chromosome. Because so many systems can be involved, the condition is serious and requires a lot of medical attention.

How Common Is Edwards Syndrome?

The prevalence of trisomy 18 is estimated at about one in every 5,000 live births. Some sources suggest around one in 6,000 to 8,000 live births. It is more common in female babies than male babies among those born alive.

Because many affected pregnancies end in miscarriage (when a baby dies before being born early in pregnancy) or stillbirth (when a baby dies before birth after a certain stage of pregnancy), the true number of conceptions with trisomy 18 is higher.

What Are the Different Types of Edwards Syndrome?

There are three main types of trisomy 18:

• Full or complete trisomy 18: Every cell has the extra chromosome 18. This is the most common form.

• Mosaic – It is mosaic trisomy 18 when some body cells are normal, and others have an extra chromosome. Because of that mixture, signs may be less severe in some cases.

• Partial trisomy 18 (due to translocation) – When a piece of one chromosome sticks to another chromosome. A piece of chromosome 18 is attached to another chromosome. This is rarer and can have variable features.

Each type can affect health, development, and life expectancy differently.

What Causes Edwards Syndrome?

The root cause of trisomy 18 is the presence of that extra chromosome 18. But how does that happen?

Risk factors:

One of the known risk factors is advanced maternal age. When the mother is older, the chance of chromosomal errors, such as nondisjunction (when chromosomes do not separate correctly while forming eggs or sperm, causing an extra one), goes up. However, even younger women can have a baby with trisomy 18, so it is not only a condition of older mothers.

Because the extra chromosome affects so much of development, growth before birth may be slower, and the baby may be smaller than expected.

Is It inherited?

Most cases of Edwards syndrome are not inherited in a straightforward way. The chromosome error usually happens by chance in the egg or sperm, or just after fertilization (when an egg and sperm join to form a baby).

In the rare cases of partial trisomy due to a translocation, there may be a slightly increased risk of recurrence (when a condition happens again in another pregnancy or later time) in future pregnancies.

It is important to emphasize that parents are usually not carriers of a “trisomy 18 gene” in the common full-trisomy cases.

What Are the Symptoms and Signs of Edwards Syndrome?

When someone has trisomy 18, there are many typical signs and symptoms. Some may be visible even before birth; others appear after the baby is born.

Common symptoms for Edward syndrome include:

• Growth delay: The baby is smaller for their stage of pregnancy and may have a low birth weight.

• Characteristic physical traits: A small head (microcephaly – a smaller-than-normal head size), a small jaw (micrognathia – a smaller-than-normal lower jaw), low-set ears, and fingers that are often clenched with overlapping digits.

• Rocker-bottom feet: Feet that are curved like the bottom of a rocking chair.

• Heart defects: Most children with trisomy 18 have congenital heart disease (heart problems that are present from birth), such as holes between chambers of the heart.

• Organ malformations: Problems with the kidneys, lungs, or the digestive system.

• Developmental and intellectual disability: Learning, walking, or speaking may be severely delayed or may not happen.

• Prenatal signs: Before birth, while the baby is still inside the mother’s womb, signs during a pregnancy ultrasound, like reduced fetal movements, growth restriction, a single artery in the umbilical cord, or too much amniotic fluid (polyhydramnios – when there is too much fluid around the baby in the mother’s womb), may hint at trisomy 18.

How Is Edwards Syndrome Diagnosed?

Diagnosis of trisomy 18 can occur before birth (prenatal) or after birth.

Prenatal diagnosis of Edward syndrome may include:

• Ultrasound screening: To look for structural abnormalities and growth delays.

• Blood tests: Non-invasive prenatal testing (NIPT - a blood test from the mother that checks for extra chromosomes in the baby) or cell-free DNA (deoxyribonucleic acid) test can help. They are blood tests from the mother that look for signs of an extra chromosome.

• Diagnostic tests: If a screening test shows a higher risk, procedures such as chorionic villus sampling (CVS - a test that takes a small piece of the placenta to look at the baby’s chromosomes) or amniocentesis (a test that takes a little fluid from around the baby to check for genetic conditions) can confirm the diagnosis.

Postnatal diagnosis after birth involves:

• Physical examination: Identifying traits such as a small head, overlapping fingers, or heart defects.

• Test: Karyotype (picture of a person’s chromosomes used to check for extra or missing ones), or chromosomal analysis (a laboratory test using a blood sample to confirm the presence of an extra copy of chromosome 18) can help.

How Is Edwards Syndrome Treated?

There is no cure in the usual sense for trisomy 18. The extra chromosome cannot be removed. Instead, trisomy 18 treatment focuses on managing symptoms, supporting development, offering comfort, and improving quality of life.

Treatment involves:

• Heart defect repair: Some surgeries may be possible depending on the child’s condition.

• Feeding support: Many children have trouble swallowing, so a feeding tube may be needed.

• Breathing support: If lungs are underdeveloped or breathing is difficult, special medical care may be necessary.

• Developmental therapies: Physical therapy, speech therapy, and occupational therapy (helps children improve everyday skills like eating, dressing, and moving) can help with comfort and small improvements in ability.

• Family and emotional support: Counseling, working with specialists, and making decisions about care goals.

Trisomy 18 specialist doctors who may be involved include geneticists (experts in genes and chromosomes), pediatric cardiologists (doctors who treat heart problems in children), neonatologists (doctors who take care of sick or premature newborn babies), and developmental specialists.

It is also important to have realistic conversations about Edward syndrome prognosis (a prediction about how an illness will progress or what the outcome may be) and what kind of support will be needed. Some families choose full active treatment; others may focus on comfort care depending on the severity of the condition.

What Is the Life Expectancy?

One of the hardest questions after diagnosis is, “How long will this child live?” The answer is that survival is limited for many, but there are exceptions.

More than half of babies born alive with trisomy 18 die within the first week of life.

Around five to ten percent of children may live past their first year. There are rare cases of survival into the teenage years, twenties, or even adulthood, especially in mosaic or partial forms.

Some studies have found the median survival (the middle number that shows how long people usually live with a certain condition) is about twelve days, but others show that calling the condition “always fatal” is not completely accurate.

Some children do live much longer than expected. When we refer to “trisomy 18 adults,” we mean the few known adults living with this condition. There have been reports of people reaching their mid-twenties or older.

Conclusion

Edwards Syndrome (trisomy 18) is a serious chromosomal condition caused by three copies of chromosome 18. It is relatively rare but not extremely uncommon (around one in 5,000 live births). Symptoms vary but often include growth delay, distinct physical findings, organ problems, and developmental challenges.

Diagnosis can be made before birth or after birth through a mix of screening and detailed tests. Edward syndrome treatment is supportive and focuses on comfort, development, and managing complications. Prognosis is challenging, as many children do not survive beyond early infancy, but some do reach childhood or adulthood, especially in mosaic or partial cases.

iCliniq Takeaways

1. Edwards Syndrome is a defect in chromosome 18 where there are three copies of this chromosome present.

2. Its diagnosis can be made pre-delivery or after the birth of the baby through certain tests and screenings.

3. If you wish to know more about this or want to consult our expert doctors at icliniq to get a check-up, do not wait.