What is Turner syndrome?
Turner syndrome is a genetic condition that only affects females. It is caused by an abnormal sex chromosome and affects about 1 in every 2,000 baby girls.
Babies are usually born with 23 pairs of chromosomes. One pair of chromosomes determines the baby's sex. This pair are known as the sex chromosomes.
One sex chromosome comes from the father and the other one comes from the mother. The mother’s contribution is always an X chromosome. The father’s contribution can either be an X or a Y chromosome.
A baby girl usually has two X chromosomes (XX) and boys have an X and a Y chromosome (XY). The Y chromosome determines ‘maleness’, so if it is missing as in Turner syndrome, the sex of the child will invariably be female.
A female with Turner syndrome has part or all of one X chromosome missing. This means the girl has just one complete X chromosome rather than two.
Read more about the causes of Turner syndrome.
Characteristics of Turner syndrome
Females with Turner syndrome often have a wide range of symptoms and some distinctive characteristics. Two that occur in almost all cases of Turner syndrome are:
- being shorter than average
- underdeveloped ovaries (female reproductive organs), resulting in a lack of monthly periods and infertility
As height and sexual development are the two main characteristics, Turner syndrome is often undiagnosed until a girl reaches puberty (sexual maturity).
Other characteristics of Turner syndrome can vary significantly between individuals. For example, the syndrome can sometimes cause heart, kidney and thyroid problems, as well as bone disorders and ear problems.
Treating Turner syndrome
There is no cure for Turner syndrome, but many of the associated symptoms can be treated.
Girls and women with Turner syndrome will need to have regular health checks throughout their lives. However, it is usually possible to lead a relatively normal and healthy life.
Life expectancy is slightly reduced but it can be improved if regular health checks are maintained and any potential problems are identified and treated at an early stage.
Read more about treating Turner syndrome.
Turner syndrome symptoms
The symptoms of Turner syndrome vary depending on the age of the girl or woman affected.
Babies born with Turner syndrome often have swollen hands and feet, which is caused by an accumulation of excess fluid in the surrounding tissues. This is known as lymphoedema, and it usually clears up soon after birth.
Other symptoms that may develop before birth include:
- thick neck tissue
- swelling of the neck (cystic hygroma)
- being a small baby
Common characteristics of Turner syndrome
The two most common characteristics of Turner syndrome are:
- short height
- ovaries that do not work properly
These affect over 9 out of 10 females with Turner syndrome and are described below in more detail.
Babies with Turner syndrome usually grow at a normal rate until three years of age. After this age, they will have a lower-than-average growth rate.
At puberty, a girl with Turner syndrome will not have the normal growth spurt. Girls usually begin puberty between 8-14 years of age.
Without treatment, a girl with Turner syndrome will grow to around 136-147cm (4ft 6in to 4ft 10in) tall. On average, adult women with untreated Turner syndrome are 20cm (8in) shorter than adult women without the syndrome. Treatment with growth hormones can reduce this difference.
Read more about growth hormone treatment in Turner syndrome.
Ovaries are the pair of reproductive organs in females that produce eggs and sex hormones. During puberty, a girl's ovaries usually begin to produce the sex hormones oestrogen and progesterone.
However, most girls with Turner syndrome will not produce these sex hormones which means that:
- unlike other girls, they may not start their monthly periods naturally
- they may not fully develop breasts
- they may be infertile (unable to have a baby)
Even though many women with Turner syndrome have undeveloped ovaries and are infertile, with hormone replacement therapy (HRT) their vagina and womb may develop normally. This will mean they are able to have a normal sex life. Girls with Turner syndrome also usually have normal pubic hair growth.
About three out of every 10 girls with Turner syndrome experience some physical changes during puberty, and a very small number may be able to become pregnant naturally.
As well as short height and non-functioning ovaries, there are many other symptoms or characteristics that can affect girls and women with Turner syndrome. Some of these are listed below.
Changes to appearance
Symptoms that affect appearance include:
- a particularly short, wide neck (webbed neck)
- a broad chest and widely spaced nipples
- arms that turn out slightly at the elbows
- a low hairline
- mouth abnormalities, which can cause problems with the teeth
- a large number of moles
- small, spoon-shaped nails
- a short fourth finger or toe
Symptoms that affect the eyes include:
- eyes that slant downwards
- droopy eyelids (ptosis)
- a squint (strabismus)
- lazy eye (amblyopia)
- cataracts – cloudy patches in the lens (the transparent structure at the front of the eye)
- short-sightedness (myopia)
Symptoms that affect the ears include:
- low-set ears
- reoccurring middle ear infections (otitis media](yourmd:/condition/otitis-media)) and [glue ear during early childhood
- hearing loss – which can occur in later life, is often more severe and develops earlier than the normal age-related decline in hearing
Turner syndrome is often associated with a number of other health conditions. Some of these are listed below.
- Heart murmur – where your heart makes a whooshing or swishing noise between beats. This is sometimes linked to a narrowing of the main blood vessel in the heart (the aorta).
- An underactive thyroid gland (hypothyroidism)which occurs in around 10-30% of women with Turner syndrome. Regular blood tests are needed to detect it early.
- High blood pressure (hypertension) – blood pressure also needs to be checked regularly.
- Osteoporosis (brittle bones) – which may develop due to the lack of oestrogen. HRT can often help prevent osteoporosis.
- Scoliosis (abnormal curvature of the spine) – occurs in about 1 in 10 teenage girls with Turner syndrome and should be screened for.
- Diabetes – a lifelong condition that causes a person's blood sugar level to become too high.
- Lymphoedema – as well as affecting unborn babies, lymphoedema can occur at any age.
- Gastrointestinal bleeding (bleeding in the digestive system) – due to abnormalities in the blood vessels in the intestines.
- Other digestive conditions – such as Crohn's disease and ulcerative colitis are also more common in females with Turner syndrome.
- Kidney and urinary tract problems – which can increase the risk of developing urinary tract infections (UTIs).
Most girls with Turner syndrome have good language and reading skills. However, some have behavioural, social and specific learning difficulties that are often overlooked by doctors, and can cause the parents great [anxiety]. They include:
- problems with social intelligence
- problems with spatial awareness and numeracy
- attention and hyperactivity problems
These are discussed below.
About a third of girls with Turner syndrome have problems understanding social relationships due to the way their brain develops.
Affected girls may find it difficult to sustain friendships, and in later life they may experience relationship problems both at home and at work.
Girls and women with Turner syndrome tend to be anxious and eager to please, which can make them vulnerable because they may be naive or lack experience in dealing with particular situations. As adults, many women with Turner syndrome prefer to work with children.
Spatial awareness and numeracy
Spatial awareness is the ability to understand where you are in relation to objects or other people. More than 8 out of 10 females with Turner syndrome have difficulty understanding spatial relationships. This may cause problems when learning to drive or when following directions on a map.
A similar number have some degree of difficulty learning or understanding maths. This is known as dyscalculia. Girls may find understanding simple mathematical rules difficult, and their concept of numbers may not be well developed. School teachers may not fully appreciate the problem, which can cause considerable stress.
Attention and hyperactivity problems
Typically, girls with Turner syndrome will go through a phase in childhood that involves:
- physical overactivity, such as constant fidgeting and restlessness
- acting impulsively, such as breaking rules or having no sense of danger
- having a short attention span and being easily distracted
Attention and hyperactivity problems usually begin when the girl is a toddler. However, they may not be a serious problem until the girl starts school at four or five years of age. Girls with Turner syndrome may have difficulty settling in class.
These may be symptoms of attention deficit hyperactivity disorder (ADHD), but medical (stimulant) treatment for the condition may not be as effective or may not work in cases of Turner syndrome.
The physical hyperactivity usually reduces around the time the girl starts secondary school at 11 years of age. However, problems with inattention can sometimes last longer, until the girl is a teenager.
Causes of Turner syndrome
Turner syndrome is a genetic condition caused by abnormal sex chromosomes.
One of the female sex chromosomes (see below) is either missing or incomplete. This causes abnormalities during the development of the unborn baby, as well as developmental problems following birth, such as short stature, ovarian failure and learning disabilities.
Chromosomes are made up of strands of DNA. Each cell in the human body contains 23 pairs of chromosomes.
Chromosomes carry genes (single units of genetic material) that are inherited from your parents and determine your physical appearance and behavioural characteristics. Medical conditions can also be inherited through faulty chromosomes.
The sex chromosomes determine whether a baby will be male or female. They can either be X or Y chromosomes. You inherit one chromosome from each parent, with a female usually having two X chromosomes (XX), and a male having one X and one Y chromosome (XY).
Read more about genetics, chromosomes and genetic inheritance.
Missing or incomplete X chromosome
Turner syndrome occurs when a baby is conceived. It only affects females who have a missing or incomplete X chromosome. If a baby is conceived with a missing X chromosome, the pregnancy will not usually develop and an early miscarriage will occur.
Approximately 95% of pregnancies conceived with Turner syndrome will end in miscarriage. However, there are many reasons for miscarriages. Overall, Turner syndrome is thought to be responsible for around 15% of miscarriages.
Who is at risk?
Turner syndrome is a fairly rare condition, affecting about 1 in every 2,000 baby girls.
Females of all races, nationalities and regions of the world can get Turner syndrome. It appears to occur randomly and is not linked to the mother’s age. It is also very rare to have a second child with Turner syndrome.
There are no known poisonous chemicals or environmental factors that cause Turner syndrome or increase the likelihood of a baby having it.
Diagnosing Turner syndrome
Turner syndrome is usually identified during childhood or at puberty. However, it can sometimes be diagnosed before a baby is born.
Pregnancy and birth
Turner syndrome may be suspected in pregnancy during a routine ultrasound scan (where high frequency sound waves are used to create an image of the developing baby).
Lymphoedema, a condition that causes swelling in the body’s tissues, can affect unborn babies with Turner syndrome, and may be visible on an ultrasound scan.
If Turner syndrome is suspected, a diagnosis can be confirmed using another prenatal test, such as:
- chorionic villus sampling – where a sample of cells is taken from the placenta and tested for genetic conditions; the placenta is the organ that links the mother’s blood supply to her unborn baby’s
- amniocentesis – where a sample of amniotic fluid is tested for genetic conditions; amniotic fluid is the fluid that surrounds the developing baby in the womb
Sometimes Turner syndrome is diagnosed at birth as a result of heart or kidney problems, or swelling of the hands and feet (lymphoedema).
If a girl has the typical characteristics and symptoms of Turner syndrome, such as a webbed neck, broad chest and widely spaced nipples, the syndrome may be suspected.
Short stature and undeveloped ovaries are the two main clinical features of Turner syndrome. Therefore, the syndrome is often identified during early childhood when a slow growth rate and other common features become apparent.
A child’s height is usually closely related to the height of their parents. Girls with Turner syndrome are typically short in relation to the height of their parents. So, an affected girl who has two tall parents may be taller than some of her peers, and is less likely to be identified based on her poor growth.
Karotyping is a type of testing that involves analysing chromosomes (the thread-like structures inside all human cells).
Karotyping is often used in cases where Turner syndrome is suspected. The test can either be carried out while the baby is inside the womb by taking a sample of amniotic fluid, or it can be carried following birth by taking a blood sample.
A specialist will count the number of chromosomes in the sample and look for any structural abnormalities in the chromosomes. Turner syndrome will be confirmed if one of the X chromosomes is absent or incomplete.
Turner syndrome treatment
There is no cure for Turner syndrome, but many of the associated symptoms, such as short stature, sexual development problems and learning difficulties, can be treated.
Regular health checks and preventative care and treatment are important for girls and women with Turner syndrome. This is because of the risk of complications.
Some hospitals have dedicated Turner syndrome clinics with a number of specialists including:
- an ear, nose and throat (ENT) specialist – who will monitor the ears with regular hearing assessments
- a paediatric endocrinologist – a specialist in conditions that affect hormones and metabolism (the process that turns food into energy) in children and teenagers
- an adult endocrinologist – a specialist in conditions that affect hormones and metabolism in adults
- a cardiologist – a heart specialist
- an obstetrician – a specialist in pregnancy and birth
- a gynaecologist – a specialist in treating conditions that affect the female reproductive system
If a girl or women is diagnosed with Turner syndrome, the following areas may be monitored throughout her life.
Hearing and ears
During childhood, middle ear infections (otitis media) are more likely to develop and need to be treated quickly. About half of all women with Turner syndrome lose their hearing at a faster rate compared with normal age-related decline.
High blood pressure (hypertension) is quite common in women with Turner syndrome, so it is important that blood pressure is regularly checked and treatment is provided, if necessary.
Thyroid function tests can be used to assess how well your thyroid gland is working, as there is also a slightly higher risk of having an underactive thyroid (hypothyroidism).
The glucose levels in your blood or urine may be checked to screen for diabetes (a lifelong condition that causes your blood sugar level to become too high).
Bone mineral density (BMD)
Women with Turner syndrome have an increased risk of developing osteoporosis (brittle bones). Your bone mineral density can be measured using a dual energy X-ray scan, which is usually known as a DEXA scan.
If you are diagnosed with any of the above conditions, you will be given appropriate treatment.
Growth hormone therapy
An endocrinologist (specialist in hormone-related conditions) will be able to carry out tests and checks on a regular basis. They will also be able to recommend appropriate treatment, such as growth hormone therapy.
Growth hormone therapy should be given to a girl with Turner syndrome as soon as it becomes apparent that she is not growing normally. It will help prevent short stature during adulthood.
Growth hormone therapy is usually started around five or six years of age. However, in cases where Turner syndrome is not diagnosed until the girl is older, it may be started later. Growth hormone therapy will usually continue until the girl is 15 or 16 years of age.
Read more about growth hormone therapy.
The guidance states that treatment with somatropin should be started and monitored by a paediatrician (a specialist in childhood conditions) with expertise in growth hormone disorders in children. As the girl gets older, her care may be transferred to an adult endocrinologist (see above).
There are a number of different types of somatropin available. The type used will be based on the needs of the individual following a discussion between the specialist and the girl and her parents, including any advantages and disadvantages of the treatment.
Treatment with somatropin should be stopped if:
- there is not enough growth in the first year of treatment
- the girl is near to her final height and has grown less that 2cm (0.8in) in a year
- the girl is unable to continue taking the medicine – for example, due to side effects (see below)
- the girl reaches her final height
Somatropin is usually given daily as a single injection. The girl’s parents can administer the injection or the girl can be taught to do it herself. The dose will depend on the girl’s size.
Side effects of somatropin can include:
- visual problems
- nausea and vomiting
- a build-up of fluid that can cause swelling in the lower limbs and feet (peripheral oedema)
- joint and muscle pain
- pins and needles
- antibody formation – where the body responds to the medicine by producing proteins that usually fight infection
- underactive thyroid
- insulin resistance – where the body’s cells do not react to insulin
- high or low levels of glucose in the blood (hyperglycaemia hypoglycaemia)
Oestrogen and progesterone replacement therapy
Following tests and checks, an endocrinologist may also recommend oestrogen and progesterone replacement therapy.
Oestrogen and progesterone are the female hormones responsible for sexual development. Oestrogen is also important in preventing osteoporosis (brittle bones).
In girls with Turner syndrome, the sex hormones do not work properly and the ovaries (the female reproductive organs) do not produce enough oestrogen.
Women with Turner syndrome will usually need regular sex hormone treatment until about 50 years of age. After this time, the body usually stops producing oestrogen and monthly periods stop. This is known as the menopause.
Oestrogen replacement therapy is usually started at the time of normal puberty or just after. In girls, the average age for the start of puberty is 11. However, it may be recommended that girls start to take oestrogen a little later, between the ages of 12 and 15, because starting treatment too early may reduce the final height that the girl is able to grow to.
Oestrogen can trigger the changes that usually happen during puberty, such as breast development, which, otherwise, girls with Turner syndrome may not experience.
Oestrogen can be given as a tablet, patch or injection. Low doses are used to start with before being gradually increased until the girl’s oestrogen levels become normal.
Progesterone replacement therapy is usually started slightly later than oestrogen and can help encourage a girl's monthly periods to start.
Most women with Turner syndrome are infertile (unable to have children). However, there is a small chance that pregnancy will occur naturally.
Therefore, girls and women with Turner syndrome should be made aware of suitable methods of contraception and how to practise safe sex.
In vitro fertilisation (IVF)
Assisted conception techniques, such as in vitro fertilisation (IVF), may be recommended for women with Turner syndrome who want to have children.
If a woman has Turner syndrome and becomes pregnant, she will need regular heart checks because the heart and blood vessels will be put under extra strain during pregnancy.
Some girls and women with Turner syndrome may develop psychological problems, such as low self-esteem or depression.
Doctors sometimes attribute these problems to physical appearance or infertility, but they are more commonly related to fundamental difficulties understanding other people’s social behaviour and how to respond appropriately. Associated problems commonly arise at home, in school and in the workplace.
Most girls with Turner syndrome have a normal level of intelligence, but some may have learning difficulties and require extra tuition at school or home.
It is important to seek help if your daughter is affected. Not all aspects of ability are affected equally so an experienced psychologist should be asked to give an opinion.
You can speak to your doctor or health visitor, or the teacher at your child’s school or nursery. The school or nursery should follow guidelines about how to assess and meet your child’s special educational needs to ensure she gets the appropriate support.
As Turner syndrome is quite rare, special education departments may not have come across a case before and may not know the best way to provide support. For example, girls with Turner syndrome may need extra time to complete tasks. Other methods of help will depend on their specific problems.