Is Turner syndrome inherited?
Turner syndrome is a genetic disorder. However, in most instances, it is not inherited. Turner syndrome is usually caused by the complete or partial loss of one of the two X chromosomes in girls. Turner syndrome usually occurs after the egg has been fertilized and appears to be a random event. Nothing the parents did caused the disorder to happen. When all of a chromosome is missing, this can be called a monosomy. When part of a chromosome is missing, this can be called a deletion. There are other abnormalities of the X chromosome that can cause Turner syndrome. Ring chromosome X is when both ends of the one of the X chromosomes break off and then the remaining ends combine to form a ring. This can cause severe problems including intellectual disability. Isochromosome Xq is when there is an extra (duplicated) copy of the long arm (q) of the X chromosome. Sometimes, in addition to a partial or complete loss of one X chromosome, there is genetic material from the Y chromosome in some cells of the body. The altered or missing X chromosome may occur in all the cells of a girl's body, or may occur only in a percentage of cells (mosaicism) with the remaining cells having two unaltered X chromosomes.
Chromosomes are found in the nucleus of every cell. Each one has a long arm called 'q' and a short arm called 'p'. Chromosomes carry the genetic material of a person in the form of genes. It is the loss of these genes that cause the signs and symptoms of Turner syndrome. Most people have 46 chromosomes; 23 inherited from their mother and 23 from their father. Twenty-two chromosomes are the same in girls and boys, but girls have two X chromosomes and boys have one X and one Y chromosome. These are called the sex chromosomes because they determine the sex of a person.
- Turner Syndrome: Other FAQs. The National Institute of Child Health and Human Development website. https://www.nichd.nih.gov/health/topics/turner/conditioninfo/pages/faqs.aspx
- Turner Syndrome. The National Organization for Rare Disorders website. https://rarediseases.org/rare-diseases/turner-syndrome/
More Inheritance Content
What are the odds that parents of a girl with Turner syndrome will have another child with the disorder?
Except for very rare instances, Turner syndrome is not inherited. The disorder is caused by the complete or partial loss of one of a girl's two X chromosomes. This occurs as a random event after fertilization. There is nothing the parents did to cause this chromosomal change and the likelihood of parents having another child with Turner syndrome is no different from any other couple, which means it is highly unlikely. Parents should talk to a genetic counselor about the genetic aspects of Turner syndrome and how it affects the family.
- Turner Syndrome. Stanford Children's Health website. http://www.stanfordchildrens.org/en/topic/default?id=turner-syndrome-90-P02421
- Learning About Turner Syndrome. The National Human Genome Research Institute website. https://www.genome.gov/19519119/