Down's syndrome

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In this article

Symptoms
Causes
Diagnosis
Treatment

What is Down's syndrome?

Down's syndrome, also known as Down syndrome, is a genetic condition that typically causes some level of learning disability and a characteristic range of physical features.

Most babies born with Down's syndrome are diagnosed with the condition after birth and are likely to have:

reduced muscle tone leading to floppiness
(hypotonia)
eyes that slant upwards and outwards
their palm may have only one crease across it (palmar crease)
a below average weight and length at birth

Although children with Down's syndrome share some common physical characteristics, they do not all look the same. A child with Down's syndrome will look more like their mother, father or other family members than other children with the syndrome.

People with Down's syndrome also vary in personality and ability. Everyone born with Down's syndrome will have a degree of learning disability. The level of learning disability will be different for each individual.

Read more about the

characteristics of Down's syndrome

Screening for Down's syndrome

In some cases, babies with the condition are identified before birth as a result of [antenatal screening for Down's syndrome]. If screening indicates there is a chance your baby has Down's syndrome, further testing is available to determine how likely it is.

Screening tests don't tell you for definite if your baby has Down's syndrome, but they can tell you how likely it is. The only way to get a definite diagnosis is for a chromosome test to be done using a sample of the baby's blood.

Who is affected?

Down's syndrome is one of the most common genetic causes of learning disability. Around 750 babies are born with the condition each year in the UK. Down's syndrome affects people of all races, religions and economic backgrounds equally.

The condition is caused by the presence of an extra copy of chromosome 21 in a baby's cells. It occurs by chance at conception and is irreversible. As yet, no one knows what causes the presence of the extra chromosome 21.

Although the chance of having a baby with Down's syndrome increases with age, babies with the syndrome are born to mothers of all ages. There is no evidence that anything done before or during pregnancy causes the syndrome.

Read more about the

causes of Down's syndrome

Living with Down's syndrome

Some families find it difficult to accept a diagnosis of Down's syndrome and it is not uncommon for parents to experience negative thoughts after the birth of their new baby.

As with most new parents, a relationship begins to develop as their baby becomes more responsive and engaging. It is important to remember that a baby with Down's syndrome has the same needs as any baby. Books, magazines and support from family and friends are just as relevant.

Although there is no "cure" for Down's syndrome, there are ways to help children with the condition develop into healthy and fulfilled individuals who are able to achieve a level of independence right for them. This includes:

access to good healthcare, including a range of different specialists
early intervention programmes to provide support for children and parents
good parenting skills and an ordinary family life
education and support groups to provide information and help for parents, friends and families

Improved education and support has presented more opportunities to people with Down's syndrome. These include the option to leave home, form new relationships, gain employment and lead independent lives.

However, it is important to remember that each child is different and it is not possible to predict how individuals will develop.

Complications

Many children with Down's syndrome have associated health conditions. Possible complications include:

heart disorders
bowel abnormalities
digestive problems
hearing and vision impairments
thyroid dysfunctions
infections
cervical spine dislocation
blood disorders

These conditions vary in severity with each individual. Some children experience none of them, while others experience several.

Your child may be checked by a paediatrician more often than other children to pick up developing problems as early as possible. If you have any concerns about your child's health, discuss them with your doctor, health visitor or paediatrician.

Read more about the

complications of Down's syndrome

Symptoms of Down's syndrome

Down's syndrome can affect a person in many different ways and each individual will experience different social and healthcare needs.

Physical appearance

People with Down's syndrome share a number of physical characteristics. Not everyone will have all of them, but they may include:

reduced muscle tone which results in floppiness
(hypotonia)
a small nose and flat nasal bridge
a small mouth
eyes that slant upwards and outwards
a big space between the first and second toe (sandal gap)
broad hands with short fingers
their palm may have only one crease across it (palmar crease)
a below average weight and length at birth

However, it is important to note that people with Down's syndrome do not all look the same and will share physical features with their parents and family.

Delayed development

All children with Down's syndrome have some degree of learning disability and delayed development, but this varies widely between individual children.

Babies with Down's syndrome also often have short arms and legs and low muscle tone, making it harder for them to learn how to move.

Certain development milestones are often affected, including:

reaching
sitting
standing
walking
communicating
talking
reading

A small proportion of children with Down's syndrome have additional medical complications that also affect their development (see

complications of Down's syndrome

Some children also experience

autistic spectrum disorders (ASD)

attention deficit hyperactivity disorder (ADHD)

These extra difficulties affect about 10% of children with Down's syndrome. Speak to the health professionals working with your family for advice or an assessment if you believe your child may be experiencing extra difficulties.

It is important to recognise that a child with Down's syndrome may still acquire many of the cognitive and social skills most other people develop. It simply takes more time, and a child should be allowed to move forward at their own pace.

Causes of Down's syndrome

Down's syndrome is a genetic condition that occurs as a result of an extra chromosome (chromosome 21).

Chromosomes

The human body is made up of cells that contain genes. Genes are grouped in thread-like structures called chromosomes.

Chromosomes are blocks of deoxyribonucleic acid (DNA) and contain detailed genetic instructions responsible for a wide range of factors, including:

how the body's cells develop
the colour of the eyes
the sex of a baby

Usually, cells contain 46 chromosomes. A child inherits 23 from the mother and 23 from the father.

In people with Down's syndrome, all or some of the cells in their bodies contain 47 chromosomes, as there is an extra copy of chromosome 21. The additional genetic material causes physical and developmental characteristics associated with Down's syndrome.

Types of Down's syndrome

There are three forms of Down's syndrome, although the effects of each type are usually the same.

Trisomy 21 is the most common type and affects around 94% of people with Down's syndrome. Trisomy 21 occurs because every cell in the body has an extra copy of chromosome 21 (trisomy is a Greek word that means "third copy").
Translocation is caused when a piece of chromosome 21 attaches itself to another chromosome in a cell. It affects around 4% of people with Down's syndrome. The symptoms of translocation Down's syndrome are similar to those of Trisomy 21, but in rare cases it may be possible for a parent to pass translocation Down's syndrome on to their child.
Mosaicism is the least common type, affecting around 2% of people with Down's syndrome. Only some of the cells have an extra copy of chromosome 21. People with mosaic Down's syndrome may experience less delay with some aspects of their development.

Some people do not have symptoms of translocation Down's syndrome but they have altered genes that can trigger the condition in their children (translocation carriers).

The risk of a translocation carrier passing on the condition to their child depends on their sex (this is due to the way chromosomes are passed down through families). That is:

male carriers have around a 1 in 35 chance of passing on the condition
female carriers have around a one in eight chance of passing on the condition

However, it is thought most cases of translocation Down's syndrome are not inherited in this way.

Increased chance

The age of a woman when she becomes pregnant (the maternal age) is the only clear factor to be identified as increasing the chance of having a baby with Down's syndrome.

For example, a woman who is:

25 years of age has a risk of 1 in 1,250
30 years of age has a risk of 1 in 1,000
35 years of age has a risk of 1 in 400
40 years of age has a risk of 1 in 100
45 years of age has a risk of 1 in 30

However, babies with Down's syndrome are born to mothers of all ages and over half of babies with Down's syndrome are born to mothers who are under 35. This is because women under 35 make up the majority of the child-bearing population.

It is not known exactly what causes the extra chromosome 21. It can come from either parent and there is no way of predicting the likelihood of a person making an egg or sperm with an extra chromosome. There is currently no clinical evidence that anything done before or during pregnancy causes the syndrome.

How is Down's syndrome diagnosed?

Antenatal screening and testing can detect the likelihood of a baby being born with Down's syndrome. However, the condition is often diagnosed after birth, when the physical characteristics of Down's syndrome are recognised.

Antenatal screening

Pregnant women of any age should be offered screening for genetic conditions such as Down's syndrome.

Antenatal screening is a way of assessing the likelihood of your baby developing, or already having developed, an abnormality during your pregnancy. It cannot diagnose conditions such as Down's syndrome, but may help with the decision to have pre-natal diagnostic tests.

You should ideally have antenatal screening for Down's syndrome by the end of your first trimester (13 weeks and six days). Most women are screened between 11 and 13 weeks. However, if necessary, it is possible to have screening up to 20 weeks into your pregnancy (this may involve more blood tests).

Read more information about antenatal appointments.

Screening tests can:

reassure you that your baby has no detected structural abnormalities
give you time to prepare for the arrival of a baby with additional needs
enable you to consider termination

Tests can also provide valuable information for your care during the pregnancy. However, no test can guarantee your baby will be born without an abnormality. No test is 100% accurate and some abnormalities may remain undetected.

If the chance of Down's syndrome (or any other condition) is shown to be high, you may be offered pre-natal diagnostic tests. These are tests to find out the likelihood of your baby being born with the suspected condition.

Combined test

The screening test used for Down's syndrome is known as the "combined test". It includes a

blood test

and

ultrasound scan

A sample of your blood is taken and tested to check the levels of certain proteins and hormones. If your blood contains abnormal levels of these substances, you may have an increased chance of having a baby with Down's syndrome.

A special type of ultrasound scan, known as nuchal translucency, measures the pocket of fluid behind the baby's neck. Babies with Down's syndrome usually have more fluid in their neck than normal. Measuring the thickness of fluid will help determine whether your baby is likely to have Down's syndrome.

Pre-natal diagnostic tests

If the results of your antenatal screening or ultrasound scan suggest your baby may have an increased chance of a condition, such as Down's syndrome, you may be advised to have further tests.

Chorionic villus sampling (CVS)

amniocentesis

both test for health problems while the baby is still in the womb.

It is important to be aware that both of these tests can result in complications, although this is uncommon. Your doctor or midwife can discuss your options with you in detail.

Chorionic villus sampling (CVS)

Chorionic villus sampling (CVS) involves taking a small sample of the placenta for closer examination. The placenta is the organ in which the foetus develops.

CVS can be performed after 10 weeks of pregnancy. The sample is taken either by passing a thin needle through the wall of your abdomen (tummy), or by passing a small tube through your vagina and the neck of your womb (cervix).

The needle or tube is guided into the correct position using an ultrasound scan. After the sample has been taken, it will be sent to a laboratory for testing. The results will show whether your baby has Down's syndrome.

Possible complications of CVS include infection, heavy bleeding and

miscarriage

. It is estimated that approximately 1 in every 100 women will have a miscarriage following CVS.

Amniocentesis

Amniocentesis involves taking a small sample of amniotic fluid (the fluid that surrounds the foetus in the womb) for examination.

Amniocentesis is usually carried out after week 15 of pregnancy, and can be carried out up until week 22. The sample of amniotic fluid is taken by passing a needle through your abdomen (tummy) and womb. The sample is drawn out through a syringe.

As with CVS, the needle is guided into the correct position using an ultrasound scan. After the sample of amniotic fluid has been taken, it will be sent to a laboratory for testing.

Possible complications of amniocentesis can include infection and injury to you or your baby.

As with CVS, there is also a 1 in a 100 chance of having a miscarriage after the procedure.

Counselling

Being told that your baby may have Down's syndrome can be difficult news to deal with. You should be offered counselling to allow you and your partner to discuss the impact of the diagnosis upon you, and talk about the available options. This will allow you to make an informed decision about how to proceed with the pregnancy.

Diagnosis after birth

Once your baby is born, the initial diagnosis of Down's syndrome is usually based on your baby's physical appearance.

Read more about the

characteristics of Down's syndrome

If your doctor needs to definitively diagnose Down's syndrome, they will arrange for a blood test called a chromosomal karyotype. A sample of your baby's blood will be taken and sent to a laboratory so that the chromosomes in the blood can be analysed. If the blood test finds that there is an extra chromosome 21, your baby will be diagnosed with Down's syndrome.

Treatment for Down's syndrome

There is no "cure" for Down's syndrome, but there is much that can be done to help someone with the condition lead a healthy, active and more independent life.

This includes:

good parenting skills and an ordinary family life
education and support groups to provide information and help to parents, friends and families
early intervention programmes to provide support for children and parents
access to good healthcare, including a range of different specialists

These are described in more detail below.

Emotional impact

In some cases, it may not be apparent a baby has Down's syndrome until after they are born. Giving birth can be exciting, scary and tiring, and finding out that your baby has Down's syndrome can be unexpected and alarming.

Some families accept their baby's diagnosis of Down's syndrome quickly, while others need time to adjust.

If you have recently found out your child has Down's syndrome, you may feel a range of emotions, such as fear, sadness or confusion. It is quite common for parents to have negative thoughts after the birth of their new baby.

There is no right or wrong way to react. Finding out more about the condition will give you a better understanding about how it may affect your child's life, as well as your own.

Many parents find it reassuring to learn more about Down's syndrome and talk to other parents. The Down's Syndrome Association can put you in touch with another family who can share their own experiences with you.

Family life

Living with a young child with Down's syndrome can be demanding, particularly in the early years. It's important to find a balance to ensure your child can grow up within a happy, loving and active family environment.

As with all new babies, they need to fit in with what is going on around them and the needs of other family members. You don't always have to do educational or meaningful activities with your child, and it can be just as beneficial to their development and happiness to do fun activities with family.

Education

Increasing numbers of children with Down's syndrome are educated in mainstream nurseries or mainstream schools with support.

However, individual needs vary and some children will benefit from attending a school or nursery that provides specialist support for children with a disability or special educational needs.

Support groups

If your child has Down's syndrome, it is important to remember you are not alone in your situation.

You may find it helpful to talk about your experiences with other families. They can offer you advice and talk through any fears or concerns you may have.

Early intervention

Early intervention programmes are widespread for children with learning disabilities and help in all areas of child development, as well as providing support to the family.

These programmes include speech and language therapy and physiotherapy, as well as individual home teaching programmes for the child and family. Being part of an early intervention programme also gives families the opportunity to find out about the syndrome, meet other families in similar situations and offer support.

During the past 30 years, extensive research has taken place looking at how people with Down's syndrome learn, and which skills are particularly challenging. There is now information for professionals and families to use that enables children to develop the skills they need to get the most out of life. Children and adults with Down's syndrome can and do continue to learn throughout their lives.

Care team

Children and adults with Down's syndrome need regular check-ups to monitor their health. Certain health problems may be more likely to develop in people with Down's syndrome, so it's important to monitor their health to detect and treat any problems as soon as possible.

Adults with Down's syndrome

Further education and employment

Many young adults with Down's syndrome pursue further education. Some also gain employment, usually on a part-time basis, although this will depend on the individual. Many people with Down's syndrome enter loving relationships, although they may need guidance and support when it comes to things such as contraception.

Living independently

With help and support, many adults with Down's syndrome are able to lead an active and independent life. Although it may not be possible to live completely independently, increasing numbers of adults with Down's syndrome are leaving home and living in their communities with support.

In most cases, adults with Down's syndrome move into property owned and staffed by a housing association. The staff provide different levels of support, depending on the individual's particular needs.

Fertility

Men and women with Down's syndrome tend to have a reduced fertility rate. This does not mean they cannot conceive children, but it does make it more difficult. Those who decide to have children will usually need specialist guidance and support to help them cope with the physical and mental demands of a newborn baby.

If a woman has Down's syndrome, the chance of her child also having the condition is 35-50%. It is difficult to estimate the likelihood if both parents have the condition because this is still a very rare occurrence. The risk of

miscarriage

and premature birth is greater in women with Down's syndrome.

Complications of Down's syndrome

Some children with Down's syndrome have very few health problems as a result of their condition. Others will experience several of the more common health conditions and will need extra medical care and attention.

Possible health complications of Down's syndrome include:

heart disorders
bowel abnormalities
digestive problems
hearing and vision impairments
thyroid dysfunctions
increased risk of infections
blood disorders
increased risk of dementia

These are outlined in more detail below.

While some of these conditions are serious, most are not. Your child may be checked by a paediatrician more often than other children to pick up developing problems as early as possible. If you have any concerns about your child's health, discuss them with your doctor, health visitor or paediatrician.

Heart disorders

Around 50% of children with Down's syndrome have a

congenital heart defect

. A congenital defect means that you are born with it. Around 60% of children with Down's syndrome who are born with a heart defect require treatment in hospital.

Septal defects account for 9 out of 10 cases of congenital heart disease in people with Down's syndrome. A septal defect is a hole inside one of the walls that separate the four chambers of the heart, often referred to as a "hole in the heart".

It can cause a build-up of blood in one or more of the heart's chambers, which causes the heart to work harder to pump blood through the four chambers.

Less common but serious types of congenital heart disease in people with Down's syndrome include:

tetralogy of Fallot, which accounts for 6% of cases
patent ductus arteriosus, which accounts for around 4% of cases

Tetralogy of Fallot is a combination of four different heart defects that causes a lowering of oxygen levels in the blood. This can lead to symptoms of breathlessness.

Patent ductus arteriosus (PDA) is a duct or passage in the heart that usually closes shortly after birth. However, in cases of PDA the duct fails to completely close, which means oxygen-rich blood that is meant to be pumped away from the lungs leaks back through the duct and into the lungs.

This can place strain on the heart and lungs because they have to work harder to compensate for the problems caused by the duct.

If your baby is diagnosed with Down's syndrome, their heart will be carefully assessed to detect and treat any problems as soon as possible.

Intestinal problems

Many people with Down's syndrome have some sort of intestinal problem. Constipation,

diarrhoea

and

indigestion

are all common, as are more serious problems such as small bowel obstruction, which stops food passing from the stomach into the large bowel.

An estimated 5-15% of people with Down's syndrome develop coeliac disease (an intolerance to gluten).

Conditions such as imperforate anus (where a baby is born without an anal opening) or Hirschsprung's disease (where the large bowel is unable to push faeces towards the anus) are rare, but slightly more common in children with Down's syndrome.

Hearing problems

Around 50% of people with Down's syndrome have problems with their ears and hearing.

Glue ear

commonly affects people with the condition. It is caused by a build-up of fluid in the middle ear. In some cases, the fluid thickens and causes sounds to be muffled and distorted.

If your child has a hearing problem, they may find it difficult to learn and interact with other children. If your child has glue ear as a result of Down's syndrome, they will usually be referred to an ear, nose and throat (ENT) specialist for treatment.

Vision problems

Around 50% of people with Down's syndrome also have problems with their eyesight.

Common eye problems include:

squint
lazy eye – where one eye does not develop fully and loses some focusing ability
short-sightedness – where distant objects appear blurred
long-sightedness
– where nearby objects appear blurred
eye infections (
conjunctivitis
,
uveitis
or
blepharitis
)
cataracts – where the lens (the transparent layer at the front of the eye) clouds over
nystagmus – where the eyes move uncontrollably, usually from side to side
keratoconus – where the cornea becomes thin and bulges out

Thyroid problems

Around 10% of people with Down's syndrome have problems with their thyroid gland. The thyroid gland is located in the neck and is responsible for controlling your metabolism (the rate at which your body uses up energy). It does this by releasing thyroid hormones into the body.

Most people with Down's syndrome who have a problem with their thyroid have hypothyroidism, which means their thyroid gland is underactive. Symptoms of an underactive thyroid gland can include:

lethargy (lack of energy)
weight gain
slow physical and mental reactions

In rarer cases, people with Down's syndrome can also develop hyperthyroidism, which means their thyroid gland is overactive and produces too much thyroid hormone. Symptoms of hyperthyroidism can include:

hyperactivity
difficulty breathing
difficulty sleeping

Increased risk of infection

People with Down's syndrome are more likely to develop infections, particularly the lung infection pneumonia. This is because their immune system (the body's natural defence against infection) has not developed properly.

Leukaemia

Children with Down's syndrome also have an increased risk of developing

acute leukaemia

Around 1 in 100 children with Down's syndrome go on to develop acute leukaemia.

Dementia

Dementia is a frequently voiced concern about people with Down's syndrome. There is a tendency for people with Down's syndrome to develop dementia at a younger age than in the general population.

However, recent research indicates that the overall percentage of adults with Down's syndrome who develop dementia is similar to that of the population who do not have Down's syndrome. It is not inevitable that people with Down's syndrome will develop the condition.

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2017

Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.