Turner Syndrome Foundation
After a child receives a diagnosis of Turner Syndrome (TS), parents and caregivers are likely to have many questions regarding their child’s health and future. One common question is whether or not TS is hereditary or somehow preventable. While there are rare exceptions,TS is not considered hereditary, meaning that it generally is not passed on from parent to child. TS is the result of a chromosomal abnormality and is a completely random mutation. There is nothing within the parents’ control that could have prevented the condition.
What Causes TS?
TS is a condition that affects 1 in 2,000 to 2,500 live female births. It is the result of a random mutation that affects one of the X chromosomes during development. A chromosome is part of the cell that contains many different genes. These genes act as blueprints for the body and provide instructions for making each person unique. We get half of each set of genes from each parent. The genes that control biological sex are the X and Y chromosomes. The X chromosome guides female development, and the Y chromosome guides male development.
Normally, those born female receive two copies of the X chromosome. TS occurs when one of the X chromosomes is partially or completely absent. During cell division, chromosomes separate equally during a phase of the cell cycle named anaphase one. TS occurs when a chromosome fails to separate–a process called nondisjunction.
There are different variations of TS, including monosomy X and mosaic TS. Monosomy X results when a random error occurs during the formation of gametes, or sex cells (sperm and egg). Mosaic TS also occurs from a random error during cell division, but the error doesn’t result in the complete absence of the X chromosome. Only part of the X chromosome is missing.
Diagnosis & Prognosis
While nothing can be done to prevent TS, early diagnosis is crucial for improving how we care for people with TS. TS can be diagnosed prenatally, but more than 50% of cases are diagnosed later on. TS is a spectrum disorder, meaning that the condition varies greatly in how it affects each person living with it.
Fortunately, through improved genetic testing and diagnostic tools, more children are being diagnosed at an earlier age. It is important that parents remember that TS is generally not hereditary and that there is nothing that they could have done to prevent it.
A diagnosis of TS can be made prenatally through amniocentesis, a procedure that analyzes cells from amniotic fluid. Chorionic villus sampling (CVS) is another test that can be used to diagnose TS. This procedure involves taking a sample of the placenta and analyzing the tissue for genetic condtions. If not picked up during pregnancy, other signs of TS might include short stature, lymphedema (swelling, especially of the hands and feet), or delayed puberty.
Children with TS are also at a higher risk for other conditions that affect the heart, kidneys, thyroid, vision, hearing, bones, and learning, making it even more important to start interventions at an early age.
Rare Exception: Partial Deletion of X Chromosome
Although the vast majority of cases are not hereditary, there is a rare exception in which TS can be passed from parent to child. A case study published in 1992 showed that mutations in the short arm of X chromosome existed in both a mother and daughter diagnosed with TS. Both had short stature but normal pubertal development. This is an important finding, as the vast majority of women with TS will also be diagnosed with premature ovarian failure and infertility. This means that a diagnosis of TS should not be discounted based solely on the presence of normal pubertal development.
According to the study, large deletions of the short arm of the X chromosome are present in only 2 to 3% of people with TS. Fertility has been documented in patients with this type of mutation, but only in a few cases has it been inherited from mother to child.
Sources
Turner Syndrome, Medline Plus
Trends in age at diagnosis of Turner syndrome, BMJ Journals
Familial Turner syndrome, National Institutes of Health/National Library of Medicine
Turner Syndrome, Cleveland Clinic
Written by Taylor Moore, TSF volunteer blog writer, and edited by Susan Herman, TSF Blog Coordinator. Designed by Jasmine Persaud, TSF volunteer blog designer.
© Turner Syndrome Foundation, 2023
