Turner syndrome, a condition that affects only girls and women, results from a missing or incomplete sex chromosome. Turner syndrome can cause a variety of medical and developmental problems, including short stature, failure to begin puberty, infertility, heart defects and certain learning disabilities.

Although Turner syndrome is usually diagnosed during infancy or early childhood, a diagnosis may be delayed for adolescent girls or young women with mild signs and symptoms.

Nearly all girls and women with Turner syndrome need ongoing medical care from a variety of specialists. Regular checkups and appropriate care can help most girls and women lead relatively healthy, independent lives.

Most people are born with two sex chromosomes. A boy inherits the X chromosome from his mother and the Y chromosome from his father. A girl inherits one X chromosome from each parent. If a girl has Turner syndrome, one copy of the X chromosome is missing or significantly altered. The genetic alterations 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 — a condition called monosomy.

  • 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, or they have one complete and one altered copy. This condition is called mosaicism.

  • Y chromosome material – In a small percentage of cases of Turner syndrome, 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 girls, but the presence of Y chromosome material increases the risk of developing a type of cancer called gonadoblastoma.

The missing or altered X chromosome of Turner syndrome causes errors during fetal development and other developmental problems after birth — short stature, ovarian failure and learning disabilities.

Signs & Symptoms

At birth or during infancy Signs and symptoms of Turner syndrome may vary significantly. In some girls, a number of physical features and poor growth are apparent early. Signs and symptoms that may be apparent at birth or during infancy include:

  • Wide or web-like neck
  • Receding or small lower jaw
  • High, narrow roof of the mouth (palate)
  • Low-set ears
  • Low hairline at the back of the head
  • Drooping eyelids
  • Broad chest with widely spaced nipples
  • Short hands
  • Arms that turn outward at the elbows (cubitus valgus)
  • Fingernails turned upward
  • Swelling of the hands and feet, especially at birth
  • Slightly smaller than average height at birth
  • Delayed growth

For some girls, the presence of Turner syndrome may not be readily apparent. Signs and symptoms in older girls, adolescents and young women that may indicate Turner syndrome include:

  • No growth spurts at expected times in childhood
  • Short stature, with an adult height of about 8 inches (20 centimeters) than might be expected for a female member of her family, without treatment
  • Learning disabilities, particularly with learning that involves spatial concepts or math
  • Difficulty in social situations, such as problems understanding other people’s emotions or reactions
  • Failure to begin sexual changes expected during puberty — due to ovarian failure that may have occurred by birth or gradually during childhood, adolescence or young adulthood and which results in little or no estrogen and other hormone production
  • Sexual development that “stalls”
  • End to menstrual cycles not due to pregnancy
  • For most women with Turner syndrome, inability to conceive a child without fertility treatment

Turner syndrome can affect the proper development of several body systems. A number of complications may occur, including:

  • Heart problems – Some people with Turner syndrome are born with heart defects or even slight abnormalities in heart structure that increase the risk of serious complications. Defects in the main blood vessel leading out of the heart (aorta) increase the risk of a tear in the inner layer of the aorta (aortic dissection). A defect in the valve between the heart and the aorta may also increase the risk of a narrowing of the valve (aortic valve stenosis).

  • Risk factors for cardiovascular disease – Women with Turner syndrome have an increased risk of diabetes and high blood pressure — conditions that increase the risk of developing diseases of the heart and blood vessels.

  • Hearing loss – Hearing loss is common among girls or women with Turner syndrome. In some cases, this is due to the gradual loss of nerve function. Also, slight abnormalities in the shape of the skull increase the risk of frequent middle ear infections and hearing loss related to these infections.

  • Kidney problems – About one-third of girls with Turner syndrome have some malformation of the kidneys. Although these malformations generally don’t cause medical problems, they may increase the risk of high blood pressure and urinary tract infections.

  • Immune disorders – People with Turner syndrome have an increased risk of certain immune system disorders, including a condition that causes an underactive thyroid (hypothyroidism). This disorder results in the low production of hormones important for controlling heart rate, growth and metabolism. There’s also an increased risk of wheat intolerance (celiac disease).

  • Dental problems – Poor or abnormal tooth development may lead to a greater risk of tooth loss. The shape of the roof of the mouth and lower jaw often results in crowded teeth and a poorly aligned bite.

  • Vision problems – Girls with Turner syndrome have an increased risk of weak muscle control of eye movements (strabismus) and farsightedness (hyperopia).

  • Skeletal problems – Problems with the growth and development of bones increase the risk of abnormal curvature of the spine (scoliosis) and forward rounding of the upper back (kyphosis). Women with Turner syndrome are also at increased risk of developing weak, brittle bones (osteoporosis).

  • Pregnancy complications – Some women with Turner syndrome can become pregnant with fertility treatment. However, most women with the disorder have relatively high-risk pregnancies. There’s an increased risk of the mother developing high blood pressure, gestational diabetes and aortic dissection.

  • Psychological issues – Girls and women with Turner syndrome may have an increased risk of low self-esteem, depression, anxiety, difficulties functioning well in social situations and attention-deficit/hyperactivity disorder.

Treatment

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

  • Growth hormone therapy is recommended for most girls with Turner syndrome. The goal of this therapy is to increase height as much as possible at appropriate times during your daughter’s childhood and adolescence. Growth hormone treatment is usually given several times a week as small, measured injections of somatropin (Humatrope, Genotropin).

  • Most girls with Turner syndrome need to begin estrogen and related hormone therapy in order to begin puberty and achieve adult sexual development. Estrogen replacement therapy usually continues throughout life, until a woman reaches the average age of menopause.

It’s important to help your daughter prepare for the transition from care with your family doctor or pediatrician to her own adult medical care. Her physician will continue to coordinate care among a number of specialists throughout her life. Regular checkups have shown substantial improvements in the quality and length of life for women with Turner syndrome. Particular problems that often arise during adulthood include hearing loss, high blood pressure, diabetes and osteoporosis.

Few 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. Therefore, it’s important to discuss timing of pregnancy with your doctor.

Some women with Turner syndrome can become pregnant with the donation of an egg or embryo. This requires a specially designed hormone therapy to prepare the uterus for pregnancy. In most cases, women with Turner syndrome have relatively high-risk pregnancies.

Source: MayoClinic.com