About monosomy x

What is monosomy x?

Turner syndrome is a rare chromosomal disorder that affects females. The disorder is characterized by partial or complete loss (monosomy) of one of the X chromosomes. Turner syndrome is highly variable and can differ dramatically from one person to another. Affected females can potentially develop a wide variety of symptoms, affecting many different organ systems. Common symptoms include short stature and premature ovarian failure, which can result in the failure to attain puberty. Most women with Turner syndrome are infertile. A variety of additional symptoms can occur including abnormalities of the eyes and ears, skeletal malformations, heart anomalies, and kidney abnormalities. Intelligence is usually normal, but affected individuals may experience certain learning disabilities. Turner syndrome may be diagnosed before birth or shortly after birth or during early childhood. However, in some cases, the disorder may not be diagnosed until well into adulthood, often as an incidental finding. The exact, underlying cause of Turner syndrome is not known. Furthermore, most cases do not run in families and appear to occur randomly for no apparent reason (sporadically).

Turner syndrome is named for Henry Turner who, in 1938, was one of the first doctors to report on the disorder in the medical literature. Turner syndrome is one of the most common chromosomal disorders and likely the most common genetic disorder of females.

What are the symptoms for monosomy x?

Small size symptom was found in the monosomy x condition

People assigned female at birth with Turner syndrome can exhibit certain characteristics during infancy and in childhood, as well as into adulthood.

Many of these symptoms can be vague and aren‘t always easy to immediately connect to Turner syndrome. If you are concerned with your child’s development at any stage, it’s a good idea to talk with their pediatrician.


Some signs of Turner syndrome during infancy include:

  • small size
  • swelling of hands and feet
  • extra folds in the neck
  • heart abnormalities
  • difficulty with feeding

Childhood and teenage years

As a person grows up, the signs of Turner syndrome may become a bit more obvious. Some of these signs include:

  • smaller in stature than most of their peers
  • below average in both height and weight
  • chronic ear infections
  • hearing issues
  • learning difficulties

One of the main symptoms of Turner syndrome is the underdevelopment of the ovaries. Because the ovaries are responsible for producing sex hormones, this underdevelopment can slow or stop the typical signs of puberty,such as breast development and menstruation, in people assigned female at birth.

Hormone therapy, such as estrogen, can help with breast development and increase the size of the uterus. It can also help with height development.


If Turner syndrome is not treated earlier, or if a person is living with a severe form of it, some of the symptoms in adulthood can include:

  • irregularities in menstrual cycle
  • hearing issues
  • heart issues
  • small stature

Having one or more of these symptoms doesn’t necessarily mean that you or your child has Turner syndrome. However, it’s always a good idea to speak with a doctor if you feel as though something is amiss when it comes to your health or the development of your child.

What are the causes for monosomy x?

Most people are born with two sex chromosomes. Males inherit the X chromosome from their mothers and the Y chromosome from their fathers. Females inherit one X chromosome from each parent. In females who have Turner syndrome, one copy of the X chromosome is missing, partially missing or changed.

The genetic changes of Turner syndrome may be one of the following:

  • Monosomy. The complete absence of an X chromosome generally occurs because of an error in the father's sperm or in the mother's egg. This results in every cell in the body having only one X chromosome.
  • Mosaicism. In some cases, an error occurs in cell division during early stages of fetal development. This results in some cells in the body having two complete copies of the X chromosome. Other cells have only one copy of the X chromosome.
  • X chromosome changes. Changed or missing parts of one of the X chromosomes can occur. Cells have one complete and one altered copy. This error can occur in the sperm or egg with all cells having one complete and one altered copy. Or the error can occur in cell division in early fetal development so that only some cells contain the changed or missing parts of one of the X chromosomes (mosaicism).
  • Y chromosome material. In a small percentage of Turner syndrome cases, some cells have one copy of the X chromosome and other cells have one copy of the X chromosome and some Y chromosome material. These individuals develop biologically as female, but the presence of Y chromosome material increases the risk of developing a type of cancer called gonadoblastoma.

Effects of the missing or changed chromosome

The missing or changed X chromosome of Turner syndrome causes problems during fetal development and other developmental problems after birth — for example, short stature, ovarian insufficiency and heart defects. Physical characteristics and health complications that arise from these chromosomal issues vary greatly.

What are the treatments for monosomy x?

Because symptoms and complications vary, treatments are tailored to address the individual's specific problems. Evaluation and monitoring for medical or mental health issues associated with Turner syndrome throughout life can help to address problems early.

The primary treatments for nearly all girls and women with Turner syndrome include hormone therapies:

  • Growth hormone. Growth hormone therapy — usually given daily as an injection of recombinant human growth hormone — is typically recommended to increase height as much as possible at appropriate times during early childhood until the early teen years. Starting treatment early can improve height and bone growth.
  • Estrogen therapy. Most girls with Turner syndrome need to start estrogen and related hormone therapy in order to begin puberty. Often, estrogen therapy is started around age 11 or 12 years. Estrogen helps to promote breast development and improve the size (volume) of the uterus. Estrogen helps with bone mineralization, and when used with growth hormone, may also help with height. Estrogen replacement therapy usually continues throughout life, until the average age of menopause is reached.

Other treatments are tailored to address particular problems as needed. Regular checkups have shown substantial improvements in the health and quality of life for girls and women with Turner syndrome.

It's important to help your child prepare for the transition from care with your pediatrician to adult medical and mental health care. A primary care doctor can help to continue coordination of care among a number of specialists throughout life.

Health care team

Because Turner syndrome can result in developmental concerns and medical complications, several specialists may be involved in screening for specific conditions, making diagnoses, recommending treatments and providing care.

Teams may evolve as needs change throughout life. Care team specialists may include some or all of these professionals, and others as needed:

  • Hormone disorder specialist (endocrinologist)
  • Specialist in women's health (gynecologist)
  • Physician who specializes in genetics (medical geneticist)
  • Heart specialist (cardiologist)
  • Specialist in skeletal disorders (orthopedist)
  • Specialist in urinary tract disorders (urologist)
  • Ear, nose and throat (ENT) specialist
  • Specialist in gastrointestinal disorders (gastroenterologist)
  • Specialist in vision problems and other eye disorders (ophthalmologist)
  • Specialist in hearing problems (audiologist)
  • Mental health professional, such as a psychologist or psychiatrist
  • Developmental therapist, who specializes in therapy to help your child develop age-appropriate behaviors, social skills and interpersonal skills
  • Special education instructors
  • Fertility specialist (reproductive endocrinologist)

Pregnancy and fertility treatment

Only a small percentage of women with Turner syndrome can become pregnant without fertility treatment. Those who can are still likely to experience failure of the ovaries and subsequent infertility very early in adulthood. So it's important to discuss reproductive goals with your health care provider.

Some women with Turner syndrome can become pregnant with the donation of an egg or embryo. A reproductive endocrinologist can discuss options and help evaluate the chances of success.

In most cases, females with Turner syndrome have high-risk pregnancies. It's important to discuss those risks before pregnancy with a high-risk obstetrician ā€• a specialist in maternal-fetal medicine who focuses on high-risk pregnancies ā€• or a reproductive endocrinologist.

What are the risk factors for monosomy x?

The loss or alteration of the X chromosome occurs randomly. Sometimes, it's because of a problem with the sperm or the egg, and other times, the loss or alteration of the X chromosome happens early in fetal development.

Family history doesn't seem to be a risk factor, so it's unlikely that parents of one child with Turner syndrome will have another child with the disorder.

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