Turner syndrome can affect the proper development of several body systems, but this varies greatly among individuals with the syndrome. Complications that can occur include:
- Heart problems. Many infants with Turner syndrome are born with heart defects or even slight abnormalities in heart structure that increase their risk of serious complications. Heart defects often include problems with the aorta, the large blood vessel that branches off the heart and delivers oxygen-rich blood to the body.
- High blood pressure. Turner syndrome can increase the risk of high blood pressure — a condition that increases the risk of developing diseases of the heart and blood vessels.
- Hearing loss. Hearing loss is common with Turner syndrome. In some cases, this is due to the gradual loss of nerve function. An increased risk of frequent middle ear infections can also result in hearing loss.
- Vision problems. An increased risk of weak muscle control of eye movements (strabismus), nearsightedness and other vision problems can occur with Turner syndrome.
- Kidney problems. Turner syndrome may be associated with malformations of the kidneys. Although these abnormalities generally don’t cause medical problems, they may increase the risk of urinary tract infections.
- Autoimmune disorders. Turner syndrome can increase the risk of an underactive thyroid (hypothyroidism) due to the autoimmune disorder Hashimoto’s thyroiditis. There is also an increased risk of diabetes. Sometimes Turner syndrome is associated with gluten intolerance (celiac disease) or inflammatory bowel disease.
- Skeletal problems. Problems with the growth and development of bones increase the risk of abnormal curvature of the spine (scoliosis) and forward rounding of the upper back (kyphosis). Turner syndrome can also increase the risk of developing weak, brittle bones (osteoporosis).
- Learning disabilities. Girls and women with Turner syndrome usually have normal intelligence. However, there is increased risk of learning disabilities, particularly with learning that involves spatial concepts, math, memory and attention.
- Mental health issues. Girls and women with Turner syndrome may have challenges functioning in social situations, may experience anxiety and depression, and may have an increased risk of attention-deficit/hyperactivity disorder (ADHD).
- Infertility. Most females with Turner syndrome are infertile. However, a very small number may become pregnant spontaneously, and some can become pregnant with fertility treatment.
- Pregnancy complications. Because women with Turner syndrome are at increased risk of complications during pregnancy, such as high blood pressure and aortic dissection, they should be evaluated by a heart specialist (cardiologist) and a high-risk pregnancy doctor (maternal-fetal medicine specialist) before pregnancy.
The syndrome can either be described as:
- classic Turner syndrome – where 1 of the X chromosomes is completely missing
- mosaic Turner syndrome – in most cells, 1 X chromosome is complete and the other is partially missing or incomplete in some way, but in some cells there may be just 1 X chromosome or, rarely, 2 complete X chromosomes
A girl with Turner syndrome only has 1 normal X sex chromosome, rather than the usual 2 (XX).
Everyone is born with 23 pairs of chromosomes. One pair of chromosomes, the sex chromosomes, determines the baby’s gender.
1 sex chromosome comes from the father and 1 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 2 X chromosomes (XX), and boys have an X and a Y chromosome (XY). A female with Turner syndrome is missing part or all of 1 sex chromosome. This means she has just 1 complete X chromosome.
The Y chromosome determines “maleness”, so if it’s missing, as in Turner syndrome, the sex of the child will invariably be female.
The loss or alteration of the X chromosome occurs randomly. Sometimes, it’s because of a problem with the sperm or the egg, and other times, the loss or alteration of the X chromosome happens early in fetal development.
Family history doesn’t seem to be a risk factor, so it’s unlikely that parents of one child with Turner syndrome will have another child with the disorder.
Females with Turner syndrome often have a wide range of symptoms and some distinctive characteristics. Almost all girls with Turner syndrome:
- are shorter than average
- have underdeveloped ovaries, resulting in a lack of monthly periods and infertility
As height and sexual development are the 2 main things affected, Turner syndrome may not be diagnosed until a girl fails to show sexual development associated with puberty, usually between the ages of 8 and 14 years.
Other characteristics of Turner syndrome can vary significantly between individuals.
Turner syndrome is usually identified during childhood or at puberty. However, it can sometimes be diagnosed before a baby is born using a test called amniocentesis.
Pregnancy and birth
Turner syndrome may be suspected in pregnancy during a routine ultrasound scan if, for example, problems with the heart or kidney are detected.
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.
Turner syndrome is sometimes diagnosed at birth as the result of heart problems, kidney problems or lymphoedema.
Childhood
If a girl has the typical characteristics and symptoms of Turner syndrome, such as short stature, a webbed neck, a broad chest and widely spaced nipples, the syndrome may be suspected.
It’s often identified during early childhood, when a slow growth rate and other common features become noticeable.
In some cases, a diagnosis is not made until puberty when breasts do not develop or monthly periods do not start.
Girls with Turner syndrome are typically short in relation to the height of their parents. But an affected girl who has tall parents may be taller than some of her peers and is less likely to be identified based on her poor growth.
Karyotyping
Karyotyping is a test that involves analysing the 23 pairs of chromosomes. It’s often used when 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 (amniocentesis) – or after birth by taking a sample of the baby’s blood.
