Quick version
Turner syndrome is a congenital chromosomal condition that affects girls and women, in which one X chromosome is completely or partially missing or altered. Many individuals have mild or no obvious symptoms, which means the condition is sometimes not discovered until later in life. Most people can live a full and healthy life, especially with appropriate medical follow-up.
Turner syndrome can sometimes be identified during pregnancy through NIPT screening. Since NIPT is a screening test and not a diagnostic test, false positive results can occur. Therefore, follow-up invasive prenatal testing is necessary to reliably confirm or rule out the diagnosis.
What is Turner syndrome?
Turner syndrome is a congenital chromosomal condition that affects only girls and women. The condition means that a person is completely or partially missing one of their two X chromosomes. Most women have two X chromosomes in every cell, but in Turner syndrome there is only one X chromosome, or one of them is incomplete. The condition arises early in fetal development and is not inherited from the parents.
How common is Turner syndrome?
It is estimated that approximately one in 2,000–2,500 girls born in Sweden has Turner syndrome. However, many more pregnancies affected by the condition result in miscarriage early in pregnancy, which means Turner syndrome is more common among fetuses than among newborns.
NIPT and detection in the fetus
NIPT is a blood test taken from the pregnant woman that analyzes small amounts of cell-free DNA from the placenta, which reflects the fetus’s genetic material. The test is used to assess the likelihood of certain chromosomal abnormalities, including Turner syndrome.
NIPT is a screening test
It is important to understand that NIPT does not provide a diagnosis. An abnormal result only means that the probability of a chromosomal abnormality is higher than normal. For Turner syndrome, the reliability is lower than for some other chromosomal changes, which means there is greater uncertainty in the result.
False positive NIPT results
False positive results occur relatively often when it comes to Turner syndrome. One common explanation is that much of the DNA being analyzed comes from the pregnant woman herself. If the mother has a mixture of cells with different chromosomal compositions, known as mosaicism, or age-related changes in her X chromosomes, this can affect the analysis. These changes may be misinterpreted as the fetus missing an X chromosome, even though the fetus actually has a normal chromosomal set.
Follow-up testing is essential
If Turner syndrome is suspected after NIPT, it is therefore necessary to proceed with invasive diagnostic testing. Chorionic villus sampling or amniocentesis analyzes the fetus’s own cells and can reliably confirm or rule out the diagnosis.
Living with Turner syndrome
Most individuals with Turner syndrome can live an active and meaningful life. With individualized care, knowledge about the condition, and regular medical follow-up, it is often possible to maintain good health and quality of life.
Symptoms and wide individual variation
Turner syndrome can cause highly variable symptoms, both in type and severity. Some individuals have significant medical needs, while others experience hardly any noticeable problems. Examples of symptoms include short stature, reduced ovarian function which may lead to absent puberty and infertility, congenital heart or kidney abnormalities, and hearing loss. Intellectual development is usually normal, and many individuals report a good quality of life.
Can Turner syndrome be diagnosed in adulthood?
Yes, it is entirely possible to receive a diagnosis of Turner syndrome only in adulthood. This is especially true for individuals with milder forms, where some cells have a normal chromosomal set. Many have few or no symptoms during childhood, and evaluation often takes place in connection with absent puberty, menstruation that never started or stopped early, fertility investigations, or when height differs significantly from the family average.
What happens if NIPT shows a chromosomal abnormality?
If an NIPT test you have taken through Testmottagningen.se shows an increased likelihood of a chromosomal abnormality, you will be contacted by a doctor for a medical review of the result. The doctor will explain what the answer means, respond to questions, and assess the need for further evaluation. If necessary, we will assist with referrals and contact with the appropriate healthcare unit for continued prenatal diagnostics, where follow-up examinations can be offered.