Turner Syndrome (2024)

What causes Turner syndrome?

Humans typically have 23 pairs of chromosomes (46 total). Chromosomes divide into 22 numbered pairs (autosomes) and one pair of sex chromosomes. You receive one chromosome from each biological parent to make a pair.

The 23rd pair normally consists of one X and one Y chromosome for people assigned male at birth (AMAB) and two X chromosomes for people AFAB. Turner syndrome happens when one of a baby’s two X chromosomes is missing or incomplete. Researchers don’t yet understand why this happens.

Types of Turner syndrome

There are different types of Turner syndrome (TS) based on how one of the X chromosomes is affected:

Monosomy X: This type means each cell has only one X chromosome instead of two. About 45% of people with TS have monosomy X. The chromosomal abnormality happens randomly during the formation of reproductive cells (eggs or sperm) in the affected person’s biological parent. If one of these atypical reproductive cells contributes to the genetic makeup of a fetus during conception, the baby will have a single X chromosome in each cell at birth.
Mosaic Turner syndrome: This type makes up about 30% of TS cases. Some of your child’s cells have a pair of X chromosomes, while other cells only have one. It happens randomly during cell division early in pregnancy.
Inherited Turner syndrome: In rare cases, babies may have inherited TS, meaning their biological parent was born with it and passed it on. This type usually happens because of a missing part of the X chromosome.

What are the symptoms of Turner syndrome?

Turner syndrome presents in many ways. It can cause several different characteristics — or features — as well as certain health conditions, which can vary in severity. Depending on the type of TS, signs of the syndrome may be apparent:

Before birth.
Shortly after birth.
In early childhood.
In early adolescence.
In adulthood.

As TS affects everyone differently, you should talk to your healthcare provider about what symptoms and features to expect or look out for based on your or your child’s unique genetic makeup.

Common features of Turner syndrome

The main feature of Turner syndrome is short stature. Almost all people with TS:

Grow more slowly than their peers during childhood and adolescence. Short stature usually becomes apparent by age 5.
Have delayed puberty and lack of growth spurts, resulting in an average adult height of 4 feet, 8 inches. (If your child receives a diagnosis early, growth hormone therapy can increase their height by up to 5 inches (average adult height 5’1”).

Another common feature is differences in sexual development. Most people with TS:

Typically don’t go through puberty unless they get hormone therapy in late childhood and early adolescence.
May not experience breast development without hormone therapy.
May not have menstrual periods (amenorrhea).
Have smaller-than-expected ovaries that may only function for a few years or not at all (primary ovarian insufficiency or POI).
Have low levels of sex hormones (like estrogen).
Have infertility.

Besides short stature, people with Turner syndrome often have certain physical traits, which may include:

Ear differences, including low-set ears, elongated ears, cup-shaped ears and thick ear lobes.
Low hairline at the back of your neck.
Small and receding lower jaw, which can affect tooth development and placement.
A short, wide neck or webbed neck (extra skin folds).
Broad chest.
Arms that point out slightly at your elbows (cubitus valgus).
A missing knuckle in a particular digit (finger or toe), making that digit shorter than the rest.
Flat feet (pes planus).
Narrow fingernails and toenails.
Multiple tiny colored spots (pigmented nevi) on your skin.

Health conditions associated with Turner syndrome

People with Turner syndrome are at an increased risk of also having certain health conditions. But not everyone with TS will develop them.

Cardiovascular conditions

People with Turner syndrome may have heart and blood vessel issues, some of which can be life-threatening. Up to 50% of people with TS are born with a congenital heart condition that affects the structure of their hearts. Cardiovascular problems can include:

Bone conditions

Bone conditions are also common with TS and may include:

Increased risk for osteoporosis and bone fractures (breaks), especially if you haven’t received estrogen therapy.
Scoliosis. This affects about 10% of people with TS.

Autoimmune conditions

TS increases your risk of certain autoimmune conditions, including:

Celiac disease.
Hashimoto’s thyroid disease (a type of hypothyroidism).
Inflammatory bowel disease (IBD).

Hearing and vision issues

Hearing and ear conditions that are common in people with TS include:

Frequent middle ear infections (otitis media), which may progress to mastoiditis and/or cholesteatoma formation. These are common between the ages of 1 and 6.
Sensorineural hearing loss. This develops in more than 50% of adults with TS.

The most common vision and eye conditions include:

Other, less common issues include red-green color blindness and blue sclera.

Other associated conditions

People with Turner syndrome may also have:

Kidney conditions: Structural problems in the kidney-urinary system happen in about 30% to 40% of people with TS. This may include horseshoe kidneys or the absence (agenesis) of a kidney. Problems with urine (pee) flow can lead to urinary tract infections (UTIs).
Metabolic syndrome: People with TS are at an increased risk for metabolic syndrome — a group of conditions that increase your risk of developing cardiovascular disease, Type 2 diabetes and stroke.
Lymphedema: This condition can cause swollen, puffy hands and feet.
Learning disabilities: People with Turner syndrome often have typical intelligence levels but a higher risk of developing learning disabilities. This usually involves issues with visual-motor and visual-spatial skills. It can be difficult to see how objects relate to each other in space. For example, driving may be difficult.
Mental health challenges: Living with Turner syndrome may lead to issues with self-esteem and/or chronic stress, which can cause anxiety and/or depression.