What is Turner’s Mosaic Syndrome?
Updated on March 18, 2024
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What is Turner’s Mosaic Syndrome?

Key Takeaways

Turner Mosaic Syndrome (TMS) is a subtype of Turner Syndrome, which is a disorder that affects sex chromosomes. Turner Syndrome is seen in people assigned female at birth. 

Normally, these people have two copies of the X sex chromosome. People with Turner Syndrome have only one copy of the X chromosome, or one normal copy and one damaged copy.

In a normal case of Turner Syndrome, all of a person’s cells will have the same abnormality. In a person with TMS, only one of their cells will have the abnormality, while others will have two healthy copies of the X chromosome.1

This is because of a genetic phenomenon called mosaicism. If you have mosaicism, some of your cells could have DNA that is slightly different from the DNA in the rest of your cells.2

Keep reading to learn more about TMS. This article will cover TMS symptoms and how the condition is diagnosed and treated. It will also go over mosaicism, how it occurs, and how it can result in TMS.

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What Are the Symptoms of Turner Mosaic Syndrome?

The symptoms and effects of TMS are similar to the symptoms of non-mosaic Turner Syndrome. These include:1,3

  • Slow growth or lack of growth spurts
  • Delayed puberty
  • Lack of breast development
  • Infertility
  • Amenorrhea (not having a period during adolescence) 
  • Difficulties with visual or spatial cognition (but not general intelligence)

However, these symptoms and effects are generally less severe in people with TMS compared to people with non-mosaic Turner Syndrome.

In some cases, symptoms can be so mild that many cases of TMS go undiagnosed. Some evidence suggests that some cases of TMS may not require any medical intervention at all.4

Turner Syndrome can also result in other health effects. These include an increased risk of cardiovascular disorders, an increased risk of diabetes, bone weakness, inflammatory bowel disease, and potential issues with the kidneys or eyes.3

What are the Common Physical Features?

Many of the most notable manifestations of Turner Syndrome are certain physical features. These include:3

  • Short stature
  • Wide neck, also known as webbed neck
  • Broad chest, also known as shield chest
  • Low-set ears

How Does Turner Mosaic Syndrome Affect Development?

People with Turner Syndrome often face developmental delays. Many of these come in the form of delays in sexual development.

This usually manifests through delayed puberty or amenorrhea. Some people with Turner Syndrome may never complete puberty without hormone therapy.1

Normally, the ovaries secrete hormones that signal the body to start puberty. People with Turner Syndrome often have ovaries that do not function or have very little function, which results in these developmental delays.4

Many people with Turner Syndrome can also experience early menopause and potentially ovarian failure a few years later.3

What is Turner's Mosaic Syndrome? 1

However, evidence shows that in people with TMS, ovarian function is usually not impacted as severely. So, while development can still be affected in people with TMS, they are much less likely to have delayed puberty or a delayed onset of periods.5

Some evidence also shows that some specific neurological effects can come with Turner Syndrome. People with Turner Syndrome usually have normal intelligence but can have difficulties with visual and spatial reasoning. 

Even though they have normal intelligence, learning disabilities are also common in people with Turner Syndrome. This could be due to visual or spatial difficulties or other reasons not directly related to the condition.1,3

How Do You Diagnose Turner Mosaic Syndrome?

If you think you may have TMS, there are several options available that can diagnose you. Different types of genetic testing can diagnose Turner Syndrome or TMS.

What Methods are Used in Diagnosis?

Karyotype

A karyotype is a common genetic test that can diagnose TMS and other sex chromosome abnormalities. This test allows doctors to examine the different chromosomes in your blood.

If you undergo a karyotype, a sample of your blood will be taken. By analyzing the DNA in your blood, this test can show if there is an abnormality in one of your sex chromosomes. An abnormality in one X chromosome would indicate Turner Syndrome or TMS.

In TMS, not all cells have an abnormality in the X sex chromosome. If a person with TMS has a karyotype test, there is a chance that it will show normal sex chromosomes.

Fluorescence In Situ Hybridization (FISH)

If your doctor suspects you may have TMS, they may perform a fluorescence in situ hybridization or FISH test. This test allows doctors to analyze your DNA in much greater detail than a karyotype. This test is usually used to diagnose TMS.

Some types of pre-natal testing can also diagnose TMS, like amniocentesis or chronic villus sampling. An ultrasound can also sometimes identify features that would indicate Turner Syndrome.1

What is Turner's Mosaic Syndrome? 2

An early diagnosis of Turner Syndrome can be beneficial because it allows doctors to respond with treatments like hormone therapy at the best possible time, making them more effective.

If someone with Turner Syndrome is started on hormone therapy earlier, they will likely grow taller than someone who started it later.3,6

Some evidence also shows that people who had their conditions diagnosed earlier tend to have a better quality of life.7

Early diagnosis can also allow doctors to proactively manage the negative health effects associated with Turner Syndrome, like the increased risks of heart disease and diabetes.3

How Does Mosaicism Play a Role?

Mosaicism is a phenomenon where a person’s cells can have two or more sets of DNA.

Humans start out as a single cell called a zygote, which contains the DNA inherited from both parents. The zygote continuously divides into more and more cells to become the body. The DNA is also copied throughout this process, which is why the DNA in all your cells is usually the same.2

Sometimes, errors can occur when cells divide, resulting in a change to the DNA sequence

If this happens early on in development, this altered DNA sequence can be present in a large number of cells. This is how mosaicism occurs and how it can lead to TMS.

What is Turner's Mosaic Syndrome? 3

Turner Syndrome occurs when an abnormality causes one copy of the X chromosome to be absent or deformed.

In non-mosaic Turner Syndrome, this occurs because of an abnormality in a sperm or egg cell involved in fertilization. This means that all the cells of the resulting fetus will carry the same abnormality.

In TMS, the abnormality occurs after the zygote has already divided. This means that only some of the fetus’s cells will carry the abnormality.1

Treatment and Management

Unfortunately, there is no cure for Turner Syndrome or TMS. However, there are a variety of options available that can help alleviate some of the effects of TMS.

Keep in mind that people with TMS usually have less severe symptoms than people with non-mosaic Turner Syndrome. In some cases with very mild symptoms, no treatment might be necessary.8

How is Turner Mosaic Syndrome Treated?

The treatments for TMS are similar to the treatments for Turner Syndrome. There is no way to directly cure TMS. However, there are ways to treat or alleviate some of its manifestations.

Growth hormone therapy

Growth hormone therapy can address the short stature that usually results from TMS.

Supplemental growth hormones are usually given to people with Turner Syndrome during childhood and adolescence when children with TMS start to seem short for their age. This usually continues all throughout adolescence until the person reaches what is thought to be their adult height.1

Growth hormone therapy can be very effective. The amount of growth people with Turner Syndrome experience when taking hormone therapy varies between studies. Some show average height gains of almost six inches, while others show average gains closer to three inches.3

Estrogen therapy

Many people with Turner Syndrome also require estrogen therapy. Some people will require estrogen therapy to start puberty and initiate changes like breast development, but estrogen replacement is usually important even when puberty starts on its own.

People with Turner Syndrome will usually start estrogen therapy when they are 11 to 12 years old. The starting dose is usually very small but increases over the years.

What is Turner's Mosaic Syndrome? 4

Even on estrogen therapy, some people can also experience amenorrhea, or the absence of menstruation at the appropriate age. Progestin replacement can be added to the estrogen therapy regimen in these cases. 

You can take estrogen supplements orally as well as through patches.9

What Additional Therapies and Interventions are Beneficial?

Turner Syndrome and TMS can have effects on other aspects of your health aside from growth and sexual development. Managing Turner Syndrome usually involves mitigating these risks as well.

Cardiovascular Tests and Screenings

Cardiovascular complications are one of the biggest risks of Turner Syndrome. People with this condition are more likely to have heart deformities that could affect their health.

They are also much more likely to have:

  • High blood pressure
  • Coronary artery disease
  • Heart failure

They are also up to a hundred times more likely to experience an aortic dissection.3

Because all of these risks can be extremely detrimental to health, screenings are important to identify these conditions as early as possible and to proactively monitor them throughout a person’s life.

Someone with TMS should make sure they consistently:

  • Go through screening tests like electrocardiograms
  • Get frequent blood pressure tests
  • Take blood pressure medicine (especially for hypertension)1
What is Turner's Mosaic Syndrome? 5

Blood Sugar Monitoring for Diabetes

People with Turner Syndrome are also more likely to have diabetes than people without Turner Syndrome. Because of this, people with Turner Syndrome should have their blood sugar measured every year starting from when they are ten years old. This is true even if they do not show any symptoms associated with diabetes.3

Kidney Screenings

Turner Syndrome can also cause abnormalities in the kidneys. When a person is diagnosed with Turner Syndrome, they will usually be given a kidney ultrasound. If the ultrasound detects any of these abnormalities, they will be referred to a nephrologist to manage this.1,3

Vitamin D Deficiency

The condition can also result in vitamin D deficiencies, weaker bones, and a greater chance of getting fractures. This can be addressed with estrogen therapy, vitamin D and calcium supplements, and screenings for vitamin D deficiency.1

Should People with Turner’s Mosaic Syndrome Manage Symptoms Like Those with Non-Mosaic Turner Syndrome?

It is important to note that how you manage TMS can be similar to how you manage non-mosaic Turner Syndrome. However, symptoms in people with TMS are usually less severe than those with non-mosaic versions of the condition.8

For example, some evidence has found that compared to non-mosaic Turner Syndrome, people with TMS tend to have better ovary function and are more likely to have normal blood sugar levels.3

Because of this, some evidence shows that medical interventions should be kept to a minimum in people with TMS.8

However, if you have or think you may have TMS, be sure to consult a doctor to learn the best course of action. While treatment may not be necessary, screening can still be important to ensure potential complications are caught early. 

Living with Turner Mosaic Syndrome

Turner Syndrome is a lifelong condition with no known cure.

People with TMS will need to live with the condition and its effects for their entire lives. Aside from the impacts that TMS can have on health, people with TMS still face other challenges that can impact their daily lives.

Luckily, there are options available for them to get help.

What Challenges Might Individuals Face?

Turner Syndrome and TMS can have great impacts on your social life.

This can stem from the physical changes caused by these conditions. These physical manifestations can cause people with the condition to feel different from others or like they don’t fit in. Turner Syndrome can also cause a reduced ability to read social cues.10

Studies also show that people with Turner Syndrome also tend to be more stressed or fatigued.11

How Can these Challenges be Mitigated?

If you have TMS, there are options for you to get assistance with the non-medical aspects of your condition.

There are several organizations dedicated to improving things for people with Turner Syndrome and TMS. Organizations like the Turner Syndrome Foundation and the Turner Syndrome Society of the United States (TSSUS) are dedicated to initiatives like research and medical education on Turner Syndrome.

They also provide services to patients that can help them get care.12,13

People with TMS can also get help from support groups for people with Turner Syndrome. TSSUS maintains a database of local support groups for people with Turner Syndrome, which you can find here.

Common Questions About Turner Mosaic Syndrome

Where Does the Term Mosaic Come From?

In genetics, the term mosaic refers to when an organism is made up of cells with differing sets of DNA. The term comes from the mosaic style of art, where a picture is formed from small tiles with different colors.14

Can Individuals with Mosaic Turner Syndrome Get Pregnant?

Unfortunately, most people with TMS and Turner Syndrome are infertile. However, there are rare cases where people with TMS have become pregnant without medical intervention.15

If you have TMS and want to conceive, there are medical options available, like in vitro fertilization with a donated egg.1

Is There a Cure for Mosaic Turner Syndrome?

Unfortunately, there is no known cure for Turner Syndrome or TMS. However, there are options available to people with TMS which can help manage many of the manifestations of the disease.

For example, growth hormone therapy can help increase height, and estrogen therapy can help initiate sexual development. 

While there is currently no known cure, research into Turner Syndrome is always evolving. Scientists are constantly learning new things about what causes the condition and its effects on human health. Potentially, this could lead to better methods for managing the condition.16

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Updated on March 18, 2024
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16 sources cited
Updated on March 18, 2024
  1. Kikkeri, N.S., and Nagalli, S. “Turner Syndrome.” StatPearls, 2023.
  2. Milani, D.A.Q., and Chauhan, P.R. “Genetics, Mosaicism.” StatPearls, 2023.
  3. Gravholt et al. “Turner syndrome: mechanisms and management.” Nature Reviews Endocrinology, 2019.
  4. Turner Syndrome.” Cleveland Clinic, 2021.
  5. Fukami, M. “Ovarian dysfunction in women with Turner syndrome.” Frontiers in Endocrinology, 2023.
  6. Apperley et al. “Mode of clinical presentation and delayed diagnosis of Turner syndrome: a single Centre UK study.” International Journal of Pediatric Endocrinology, 2018.
  7. Krantz et al. “Health-Related Quality of Life in Turner Syndrome and the Influence of Growth Hormone Therapy: A 20-Year Follow-Up.” The Journal of Clinical Endocrinology and Metabolism, 2019.
  8. Tuke et al. “Mosaic Turner syndrome shows reduced penetrance in an adult population study.” Genetics in Medicine, 2019.
  9. Hasegawa et al. “Pubertal induction in Turner syndrome without gonadal function: A possibility of earlier, lower-dose estrogen therapy.” Frontiers in Endocrinology, 2023.
  10. Social Skills and Relationships in Turner Syndrome: a Study.” Turner Syndrome Foundation, 2022.
  11. van den Hoven et al. “A value-based healthcare approach: Health-related quality of life and psychosocial functioning in women with Turner syndrome.” Clinical Endocrinology, 2020.
  12. Our Mission.” Turner Syndrome Foundation.
  13. Turner Syndrome Society of the United States (TSSUS).” Turner Syndrome Foundation of the United States.
  14. Leshin, L. “Mosaic Down Syndrome.” International Mosaic Down Syndrome Association.
  15. Sabzevar et al. “Pregnancy in a Patient With Mosaic Turner Syndrome: A Case Report.” Case Reports in Clinical Practice, 2020.
  16. Huang, et al. “A Review in Recent Developments in Turner Syndrome Research.” Journal of Cardiovascular Development and Disease. 2021.
Will Hunter
Will Hunter
Content Contributor
Will is a content writer for KnowYourDNA. He received his B.A. in Psychology from the University of California, Los Angeles. Will has 7 years of experience writing health-related content, with an emphasis on nutrition, alternative medicine, and longevity.