Turner syndrome

Definition

Turner syndrome is a genetic condition that occurs only in females. Female cells normally have two X chromosomes. In Turner syndrome, the girl's cells are missing an X chromosome, or part of an X chromosome. There are a variety of signs and symptoms that can result, but the most common are short height, lack of developing ovaries, and infertility.

Causes, incidence, and risk factors

Humans have 46 chromosomes, which contain all of a person’s genes and DNA. Two of these chromosomes, the sex chromosomes, determine a person’s gender. Both of the sex chromosomes in females are called X chromosomes. (This is written as XX.) Males have an X and a Y chromosome (written as XY). The two sex chromosomes help a person develop fertility and the sexual characteristics of their gender.

In Turner syndrome, the girl does not have the usual pair of two complete X chromosomes. The most common scenario is that the girl has only one X chromosome in her cells. Some girls with Turner syndrome do have two X chromosomes, but one of the X chromosomes is incomplete. In another scenario, the girl has some cells in her body with two X chromosomes, but other cells have only one.

Turner syndrome occurs in about 1 out of 2,000 live births.

Symptoms

Possible symptoms include a combination of:

• Short height
• Webbed neck
• Drooping eyelids
• A "shield-shaped", broad, flat chest
• Absent or incomplete development at puberty, including sparse pubic hair and small breasts
• Infertility
• Dry eyes
• Absent menstruation
• Absent normal moisture in vagina; painful intercourse

Signs and tests

Turner syndrome can be diagnosed at birth or during childhood, puberty, or adulthood. It can be diagnosed before birth if a karyotype is performed as part of prenatal testing.

During a physical examination, the doctor will look for signs of underdeveloped breasts and genitalia, webbed neck, short stature, low hairline in back, simian crease (a single crease in the palm), and abnormal bone development of the chest.

Infants with Turner syndrome often have swollen hands and feet. This is probably from changes in the drainage of the lymphatic system.

The following tests may be performed:

• Karyotyping to look at chromosomes
• An ultrasound to look for small or underdeveloped female reproductive organs
• A kidney ultrasound to evaluate kidney abnormalities
• A gynecologic exam to see if the vaginal lining is dry
• Serum luteinizing hormone levels -- may be high
• Serum follicle stimulating hormone levels -- may be high
• An echocardiogram (heart ultrasound) and MRI of the chest are frequently performed after the diagnosis is made to evaluate possible cardiac defects

• estriol - urine
• estriol - serum
• estradiol

Treatment

• Growth hormone may be considered to help a child with Turner syndrome grow taller.
• Estrogen therapy is often started at 12 or 13 years old to stimulate the development of breasts, pubic hair, and other sexual characteristics.
• Donor egg programs are available for women with Turner syndrome who wish to become pregnant.

Support Groups

For additional information and resources, see www.turnersyndrome.org.

Expectations (prognosis)

Those with Turner syndrome can have a normal lifespan and productive life when carefully monitored by their physician.

Complications

• Heart defects
• Kidney abnormalities
• High blood pressure
• Obesity
• Diabetes
• Hashimoto's thyroiditis
• Cataracts
• Arthritis
• Scoliosis (in adolescence)
• Middle ear infections -- common with eustachian tube abnormalities

Prevention

There is no known way to prevent Turner syndrome.

Illustrations

Pectus excavatum

Page Content:

Bonnevie-Ullrich syndrome; Gonadal dysgenesis; Monosomy X ; dysgenesis gonadal; dysgenesis gonadal mixed; monosomy x