Turner syndrome: what it is, symptoms, diagnosis, treatment and fertility

Humans are usually born with 46 chromosomes arranged in 23 pairs, the last pair being the sex chromosomes. The Yorkshire Regional Genetics Service explains that girls usually have two X chromosomes. In Turner syndrome a girl is born with only one X chromosome in each cell, or with part of one X chromosome missing. The NHS describes it as a rare genetic condition caused by a missing or partially missing sex chromosome.

In about half of cases, one X chromosome is missing or changed in some but not all cells of the body, which is called mosaic Turner syndrome. Girls with the mosaic form often have fewer features and are more likely to enter puberty naturally. The Turner Syndrome Support Society describes Turner syndrome as a chromosome abnormality affecting only females.

The NHS says there are lots of possible symptoms and everyone is affected differently, but almost everyone will be born smaller than usual and grow up shorter than average, and have underdeveloped ovaries. The Yorkshire Regional Genetics Service says most girls have some but not all of the features listed below.

The NHS says Turner syndrome may be diagnosed at birth or during childhood when typical features are noticed, with a blood test confirming the diagnosis, and during pregnancy if problems with the heart or kidneys are found on routine ultrasound scans. If a maternity team thinks a baby could have it, chorionic villus sampling (CVS) or amniocentesis may be offered.

The Yorkshire Regional Genetics Service adds that it may be suspected shortly after birth because of an unusually wide neck, puffy hands and feet or a heart problem, but is often not diagnosed until early childhood when a girl is not growing as expected, or in the teenage years when periods or puberty do not start. Diagnosis is confirmed through a genetic blood test.

There is currently no cure for Turner syndrome, but the NHS says there are treatments and support to help children and adults have the best possible quality of life. A range of health professionals may be involved, creating a care plan based on symptoms.

On growth, the Yorkshire Regional Genetics Service says girls are usually referred to a child growth specialist (paediatric endocrinologist). Although girls with Turner syndrome do not have growth hormone deficiency, growth hormone is often used to increase final height. On puberty it says oestrogen is used to start breast development, and progesterone and oestrogen together help produce regular periods. Adult women need regular monitoring under an endocrinologist.

The NHS says underdeveloped ovaries can cause infertility. The Yorkshire Regional Genetics Service explains that in most girls the eggs in the ovaries disappear in early childhood and the ovaries stop functioning before puberty would normally begin, so girls are rarely able to become pregnant naturally. A very small proportion who enter puberty naturally may be fertile for a short time.

It adds that girls with Turner syndrome have a normal womb and vagina and can have an entirely normal sex life, and some women have had successful pregnancies using donated eggs and in vitro fertilisation (IVF).

The NHS says Turner syndrome is caused by a missing or partially missing sex chromosome and that it is not possible to prevent. Very rarely it can be passed to a child by a parent, but most of the time it happens by chance. It is not linked to age or anything the parents did before or during pregnancy.

The Yorkshire Regional Genetics Service says it occurs when there is loss or alteration of an X chromosome during the making of sperm or eggs or in the early embryo, that it is not known why this happens, and that no risk factors such as maternal age or diet in pregnancy have been identified. It is not usually inherited.

The NHS says most people with Turner syndrome should be able to live a relatively normal, healthy life, but some of the health problems can be serious, so it is important to have regular health checks and get early treatment if needed. The Yorkshire Regional Genetics Service says the heart, kidneys and reproductive system should be checked regularly throughout life.

Some people experience problems at school, home or work if they have learning difficulties, or during puberty, which can lead to low self-esteem or depression. Turner syndrome is different for everyone. The Turner Syndrome Support Society is a UK charity providing information and support for girls and women with Turner syndrome. Your care team will pass information to the National Congenital Anomaly and Rare Disease Registration Service, and you can opt out at any time.

See a GP if a girl is growing noticeably more slowly than expected, or if puberty or periods have not started by the expected age, as these can be the first signs. Anyone with Turner syndrome who develops new chest pain, breathlessness, severe headaches or any sudden change in health should seek urgent medical advice from NHS 111 or, in an emergency, call 999.

On the NHS, care is usually coordinated by paediatric endocrinology and clinical genetics teams, then adult endocrinology, with cardiology, renal and hearing checks as needed. Growth hormone for eligible girls is prescribed by specialist teams. Private endocrinology, genetics and fertility consultations are available to some families, but it helps to keep the NHS team informed so that monitoring and prescribing stay joined up.