Also known as 45,X; Monosomy X; Mosaic Turner Syndrome
What is Turner syndrome?
Turner syndrome (TS), also known as 45,X; monosomy X; mosaic Turner syndrome, is a sex chromosome aneuploidy affecting approximately 1 in 2,000-2,5000 girls, caused by the complete or partial absence of a second X chromosome. The symptoms can vary from person to person but typically it is characterized by short stature, congenital heart defects, kidney malformations, ovarian failure, infertility, as well as increased risks for autoimmune and metabolic disorders, hearing loss, learning disabilities, and social or behavioral challenges. While 45,X, also known as monosomy X (when the entire X chromosome is missing) is the most common genetic finding in Turner syndrome, other karyotypes are possible, such as structural abnormalities in the second X chromosome or mosaicism resulting in multiple cell lines in a single person.
Who gets Turner syndrome?
Approximately 1 in 2,000-2,500 girls are born with Turner syndrome.
What causes Turner syndrome?
Turner syndrome is caused by the complete or partial absence of a second X chromosome in girls. It is not typically an inherited condition, but occurs due to an absent X chromosome or partial loss of the second X due to structural abnormalities such as isochromosomes, deletions or rings. Sometimes Turner syndrome is mosaic, in which there is more than one result found, such as 45,X/46,XX or 45,X/47,XXX or may include X chromosome structural abnormalities. Mosaicism may lead to a variable range of physical and developmental features related to Turner syndrome. Symptoms and severity vary depending on the type and proportion of atypical cells, as well as can lead to a delay in diagnosis. When mosaicism is 45,X/46,XX, symptoms may be more mild and surveillance for the onset of any symptoms will be most informative, including growth and ovarian functioning. Since mosaicism proportions are most commonly identified in a single tissue source, such as blood or a cheek swab, it is impossible to know the proportion of cell types in other tissue types (i.e. brain, ovaries, etc).
How is Turner syndrome diagnosed?
Turner syndrome is best diagnosed from a blood test called a karyotype, analyzing 30+ cells, looking at the number and structure of chromosomes. Other genetic tests which may diagnose Turner syndrome include a chromosomal microarray or genetic sequencing. Turner syndrome may be suspected based on physical features or growth delays, and can be identified before birth by prenatal screening and/or diagnostic testing, such as an amniocentesis.
What is the treatment for Turner syndrome?
Treatments for Turner syndrome are specific to managing symptoms, and there are published care guidelines a doctor can follow to ensure they are providing comprehensive care. Common treatments include growth hormone therapy to increase height, hormone therapy to induce puberty and support bone health, surgical interventions for cardiac abnormalities, fertility monitoring and interventions, and psychological and/or academic supports, as indicated. Girls with Turner syndrome who are found to also have Y chromosome material present are recommended to have a surgery, called a gonadectomy, to decrease their risk for developing gonadal tumors.
Frequently Asked Questions
Why did I get Turner syndrome?
Turner syndrome is not caused by anything a person does or doesn't do, as it results from a biological process in which the chromosomes misdivide, called nondisjunction.
Will my Turner syndrome get worse?
The symptoms associated with Turner syndrome may or may not change overtime. Some symptoms, such as congenital heart defects, are present at birth and monitored throughout life, whereas other symptoms, such as short stature, may become more apparent as growth velocity decreases later in childhood.
What things can I discuss with my primary care physician about Turner syndrome?
There are 2024 published care guidelines that help ensure patients with Turner syndrome are receiving comprehensive care. Talk with your doctor to make sure that your care is consistent with these recommended guidelines.