Edwards’ syndrome

Edwards' syndrome, also known as trisomy 18, is a genetic condition. It starts to affect babies while they're still in the womb, and it goes on affecting their health throughout their life. It's rare, but it is serious.

In the UK, around 3 in every 10,000 births are affected by Edwards' syndrome.

When a baby is conceived (made), they inherit genetic material from both parents. This genetic material is carried in structures called chromosomes.

Humans normally have 23 pairs of chromosomes. In each pair, 1 chromosome comes from the mother and 1 comes from the father.

A baby with Edwards' syndrome has inherited an extra copy of chromosome 18. The extra copy can be present in some or all of the baby's cells, and it can lead to health problems for the baby.

There are 3 different forms of Edwards' syndrome:

In full form Edwards' syndrome, the baby has inherited a complete extra copy of chromosome 18, and it is present in all of the baby's cells. Around 94% of babies born with Edwards' syndrome have this full form.

In mosaic form, the baby has also inherited a complete extra copy of chromosome 18, but the copy is only present in some of the baby's cells.

In partial form, the baby has inherited only part of an extra copy of chromosome 18. This is a very rare form of Edwards' syndrome.

Most cases of Edwards' syndrome happen because of a random change in the egg or sperm. The parents are healthy, and nothing they did before or during pregnancy caused this change.

You'll be offered screening for Edwards' syndrome when you're between 11 and 14 weeks pregnant. The screening test shows whether your baby has a high or low chance of having the condition.

If screening shows a high chance that your baby has Edwards' syndrome, you can choose to have a further diagnostic test if you wish.

If you get a very high chance result (between "1 in 2" and "1 in 10"), this may affect your options for further screening. This is because NIPT is less accurate if you've had a very high chance result for Edwards' syndrome or Patau's syndrome. Your doctor will talk through the next options with you.

No test can tell you if your baby has full, mosaic or partial Edwards' syndrome, or how they'll be affected.

Around 7 in 10 (70%) of pregnancies diagnosed with Edwards' syndrome from screening tests will end in miscarriage or stillbirth. The risk of miscarriage falls as the pregnancy goes on, but there's still a risk of stillbirth.

If your baby has Edwards' syndrome, it's likely they will also have other health conditions that often go with it. Some of these may be serious. Exactly how your baby is affected will depend on the form of Edwards' syndrome they have.

Full form Edwards' syndrome is considered a life-limiting condition. This means it can affect how long a baby can live.

Around 5 in 10 (52.5%) will live longer than 1 week. Around 1 in 10 (12.3%) will live longer than 5 years.

Babies born with the full form will have a learning disability, which may be severe. They're also likely to have many different health conditions, and some of these can be serious. Statistically:

• around 9 in 10 (90%) will have heart issues
• around 5 in 10 (50%) will have seizures
• around 5 in 10 (50%) will have hearing loss
• around 5 in 10 (50%) will have joint contractures (shortening of muscle tissue that can cause a deformity)
• around 1 in 10 (10%) will have a cleft lip and/or palate

Currently we can't predict how babies with mosaic or partial forms of Edwards' syndrome will be affected. This is because it depends on:

• how many cells contain the extra chromosome (mosaic)
• how much of the extra chromosome they have (partial)

Some babies may have severe health problems like those seen in the full form. Others may have much less serious health issues. There are even cases where the baby seems to have no health issues at all.

Many babies with the mosaic form will have some form of learning disability and developmental delay (when a child takes longer to start doing certain activities, like walking and talking, than other children their age).

Life expectancy for babies with mosaic or partial forms is also very variable. Some will live long lives, while others will have a much shorter life expectancy.

Every child with Edwards' syndrome is unique, and the condition affects each one differently. Like any child, they have their own personality, their likes and dislikes, and the things that make them who they are.

Babies with full form Edwards' syndrome usually have a low birthweight and are considered "medically fragile". This means they are at high risk of infections and of complications that need treatment in hospital. They may also:

• have difficulty feeding and may need to be fed by a tube
• have difficulty breathing and have apnoea (pauses in their breathing)

Their needs are complex, but children with Edwards' syndrome can still make progress with their development, although slowly.

Many children are reported to be able to communicate their needs and show awareness of their surroundings, and some can sit and stand with support. There are also cases of older children attending school.