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 in females.

Turner syndrome may be suspected prenatally based on prenatal cell-free DNA screening ― a method to screen for certain chromosomal abnormalities in a developing baby using a blood sample from the mother ― or prenatal ultrasound. Prenatal ultrasound of a baby with Turner syndrome may show:

• Large fluid collection on the back of the neck or other abnormal fluid collections (edema)
• Heart abnormalities
• Abnormal kidneys

At birth or during infancy

Signs of Turner syndrome at birth or during infancy may include:

• Wide or weblike neck
• Low-set ears
• Broad chest with widely spaced nipples
• High, narrow roof of the mouth (palate)
• Arms that turn outward at the elbows
• Fingernails and toenails that are narrow and turned upward
• Swelling of the hands and feet, especially at birth
• Slightly smaller than average height at birth
• Slowed growth
• Cardiac defects
• Low hairline at the back of the head
• Receding or small lower jaw
• Short fingers and toes

In childhood, teens and adulthood

The most common signs in almost all girls, teenagers and young women with Turner syndrome are Short stature and ovarian insufficiency due to ovarian failure. Failure of the ovaries to develop may occur at birth or gradually during childhood, the teen years or young adulthood. Signs and symptoms of these include:

• Slowed growth
• No growth spurts at expected times in childhood
• Adult height significantly less than might be expected for a female member of the family
• Failure to begin sexual changes expected during puberty
• Sexual development that "stalls" during teenage years
• Early end to menstrual cycles not due to pregnancy
• For most females with Turner syndrome, inability to conceive a child without fertility treatment

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.

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 ― a specialist in maternal-fetal medicine who focuses on high-risk pregnancies ― or a reproductive endocrinologist.

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.