Turner Syndrome

What Turner syndrome is

Most people have 46 chromosomes, including two sex chromosomes: XX in females and XY in males. In Turner syndrome, a girl has only one complete X chromosome. The missing genetic material, particularly the SHOX gene that affects bone growth, explains many of the features.

Chromosome patterns (karyotypes)

People with mosaic Turner syndrome often have milder features and are more likely to go through puberty naturally. Those with Y material have a raised risk of a tumor called gonadoblastoma, so the ovaries (gonads) are usually removed.

Is it inherited?

Almost never. The X is usually lost during the formation of the egg or sperm or very early after conception. It is not caused by anything the parents did, and the chance of it happening again in a later pregnancy is not increased.

Signs of Turner syndrome by age

Before birth and at birth

• swelling of the hands and feet (lymphedema)
• extra skin or webbing at the back of the neck
• heart defects, especially coarctation of the aorta
• sometimes found on prenatal ultrasound or blood screening, then confirmed by testing

Childhood

• short stature: often the main sign, with growth slowing from early childhood. Untreated adult height averages about 20 cm (8 inches) shorter than expected for the family, around 143 cm (4 feet 8 inches)
• low hairline at the back of the neck, webbed neck, broad chest with widely spaced nipples
• arms that turn out slightly at the elbows, short fourth fingers or toes
• narrow, high-arched palate, small lower jaw, crowded teeth
• many moles (nevi)
• frequent middle ear infections
• nails that are narrow or turned up

Adolescence

• absent or incomplete breast development
• no periods (primary amenorrhea) or periods that start and then stop
• growth that does not show a pubertal spurt

Some girls, especially with mosaicism, have very few visible features and are diagnosed only when puberty is delayed or in adulthood during evaluation for infertility.

Health problems associated with Turner syndrome

• Ovarian insufficiency: the ovaries develop but lose their eggs early, often before birth or in childhood. Most need estrogen to start puberty. See primary ovarian insufficiency.
• Heart and aorta: a bicuspid aortic valve (in roughly a quarter), coarctation of the aorta, and widening of the aorta. The risk of aortic dissection, a tear in the aorta wall, is much higher than in other young women, especially in pregnancy.
• High blood pressure, even in childhood.
• Kidney differences: horseshoe kidney or a duplicated collecting system, which can raise the risk of urinary infections.
• Hearing loss: from ear infections in childhood and progressive inner ear hearing loss in adulthood.
• Autoimmune conditions: hypothyroidism (Hashimoto's), celiac disease, type 1 diabetes and inflammatory bowel disease.
• Type 2 diabetes and high cholesterol.
• Bone thinning if estrogen is not replaced.
• Liver enzyme elevations, usually mild.
• Eye problems: strabismus and nearsightedness.

Learning and development

Most people with Turner syndrome have normal intelligence. Common specific difficulties include math, spatial awareness, visual memory, attention and some social skills, while verbal skills are often strong. Early educational assessment and support help. Anxiety and low self-esteem, often linked to short stature and infertility, benefit from support.

Diagnosis

• Karyotype: a blood test that counts chromosomes in at least 30 cells. It confirms the diagnosis and identifies the pattern. Additional tests look for Y material.
• Prenatal: non-invasive prenatal blood screening can suggest Turner syndrome, but results must be confirmed with amniocentesis, chorionic villus sampling or testing after birth. Many mosaic results on screening are mild or false positives.
• At diagnosis: heart ultrasound (echocardiogram) and cardiac MRI when old enough, kidney ultrasound, hearing test, thyroid, liver and blood sugar tests, and celiac screening.

Treatment

Growth hormone

Daily injections of growth hormone, usually started around ages 4 to 6 or as soon as growth falls behind, increase adult height by an average of about 5 to 8 cm (2 to 3 inches), more if started early. Treatment continues until bone growth is nearly complete.

Estrogen replacement

Low-dose estrogen is usually started around ages 11 to 12, then increased gradually over about 2 to 3 years to mimic natural puberty. Progesterone is added later to bring on periods and protect the womb lining. Estrogen is continued until about the typical age of menopause, around 50, to protect bones, the heart and brain, and sexual health.

Fertility

• About 1 in 3 girls, mainly with mosaicism, begin puberty naturally, and a small minority conceive naturally.
• Freezing eggs or ovarian tissue may be offered to some adolescents who still have ovarian function.
• Pregnancy using donor eggs with IVF is possible, but because of the risk of aortic dissection, a full heart assessment with MRI is required beforehand, and pregnancy is managed by a high-risk team. Some women are advised not to carry a pregnancy.

Lifelong care

Regular checks with an endocrinologist and cardiologist include blood pressure, heart imaging every few years, hearing, thyroid, blood sugar, liver tests, cholesterol, celiac screening and bone density. Many centers offer transition clinics from pediatric to adult care.

Outlook

Most girls and women with Turner syndrome attend mainstream school, work, live independently and have relationships. Life expectancy is somewhat shorter than average, mainly because of heart and aortic problems, which is why heart monitoring and blood pressure control are so important.

Frequently asked questions

What are the main symptoms of Turner syndrome?

The most common features are short stature and delayed or absent puberty because the ovaries stop working early. Other signs can include a webbed neck, low hairline, puffy hands and feet at birth, frequent ear infections, and heart or kidney differences.

Is Turner syndrome inherited?

Almost never. It usually results from a random error when the egg or sperm forms or very early in development. Parents of a child with Turner syndrome do not have a higher chance of having another affected child.

Can women with Turner syndrome have children?

Some can. A small number with mosaic Turner syndrome conceive naturally. Many become mothers through IVF with donor eggs or adoption. Pregnancy carries a high risk of aortic dissection, so careful heart screening and specialist care are essential beforehand.

What is the life expectancy with Turner syndrome?

Life expectancy is somewhat lower than average, mainly due to heart and blood vessel disease. With regular heart monitoring, blood pressure control, estrogen replacement and treatment of diabetes and thyroid disease, many women live long, healthy lives.

What is mosaic Turner syndrome?

In mosaic Turner syndrome, some cells have one X chromosome and others have two. Features are often milder, and natural puberty and pregnancy are more likely than with 45,X. The same health screening is still recommended.