Patau's syndrome

Patau's syndrome, also known as Trisomy 13, is a rare but serious genetic condition. It begins to affect babies when they're in the womb, and will continue to cause health problems throughout their life.

In the UK, around 2 in every 10,000 births are affected by Patau’s syndrome.

What is Patau's syndrome?

When a baby is conceived (made), they inherit genetic material from both their parents. This genetic material is called a chromosome.

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

If a baby has Patau's syndrome, they have inherited an extra copy of chromosome 13. This extra copy can be present in some or all of the baby's cells and can lead to health problems for the baby.

There are 3 different forms of Patau's syndrome:

Full form

In full form Patau's syndrome, the baby has inherited a complete extra copy of chromosome 13. This extra copy is present in all of the baby's cells.

Around 80% of babies born with Patau's syndrome have the full form of the syndrome.

Mosaic form

In mosaic form Patau's syndrome, the baby has inherited a complete extra copy of chromosome 13, but the copy is only present in some of the baby's cells.

Partial form

In partial form Patau's syndrome, the baby has only inherited part of an extra copy of chromosome 13. This is a very rare form of Patau's syndrome.

Why does Patau's syndrome happen?

Most cases result from a random change in the egg or sperm in healthy parents. This change is not caused by anything the parents did before or during pregnancy.

Effects of Patau's syndrome on pregnancy

Screening for Patau's syndrome

You’ll be offered screening for Patau's syndrome when you're between 11 and 14 weeks pregnant.

The screening test will show if your baby has a high or low chance of having Patau's syndrome.

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

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

Risk of miscarriage and stillbirth

Around 7 in 10 (70%) of pregnancies diagnosed with Patau's syndrome from screening tests will end in miscarriage or stillbirth.

The risk of miscarriage decreases as the pregnancy progresses, but there's still a risk of stillbirth.

Effects of Patau's syndrome on babies

If your baby is affected by Patau's syndrome, it's likely they will have some health conditions. Exactly how your baby is affected will depend on the form of Patau's syndrome they have.

Babies with full form Patau's syndrome

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

Around 4 in 10 (43.1%) babies with full form Patau's syndrome will live longer than 1 week. Around 1 in 10 (9.7%) will live longer than 5 years.

Babies born with full form Patau's syndrome will have a learning disability that may be severe. They're also likely to have a wide range of health conditions, some of which can be serious. Statistically:

around 8 in 10 (80%) will have heart issues
around 6 in 10 (60%) will have cleft lip and/or palate
around 6 in 10 (60%) will have issues with brain development
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 5 in 10 (50%) will have eye issues or an absent eye

Babies with mosaic form and partial form Patau's syndrome

Currently we can't predict how babies with mosaic or partial forms of Patau's 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 full form Patau's syndrome. Other babies may have much less serious health issues. There are even cases where the baby seems to have no health issues at all.

Most babies with a form of Patau's syndrome will have some form of learning disability.

The life expectancy for babies with mosaic or partial forms of Patau's syndrome is also very variable. Some will live long lives, while others will have a much shorter life expectancy.

Living with Patau's syndrome

Each child is unique, and Patau’s syndrome will affect each child differently. Like all children they will have their own personalities, likes and dislikes, and things that make them who they are.

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

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

Despite their complex needs, children with Patau's syndrome can make progress with their development, although slowly.

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

Feedback from many parents suggests that children with Patau's syndrome have a good quality of life and are valued members of the family.

Further information and support

You can find out more information about Patau’s syndrome, including stories from parents of a child with the syndrome, at SOFT UK (Support Organisation for Trisomy 13/ 18)