Turner syndrome is a sex chromosome abnormality in which girls are born with one of their two X chromosomes partially or completely missing.
Turner syndrome is caused by the deletion of part or all of one of the two X chromosomes.
Girls with the syndrome are typically short and with loose skin on the back of the neck, learning disabilities, and an inability to undergo puberty.
The diagnosis is confirmed by analyzing the chromosomes.
Treatment with hormones can stimulate growth and initiate puberty.
Chromosomes are structures within cells that contain DNA and many genes. Genes are segments of deoxyribonucleic acid (DNA) and contain the code for a specific protein that functions in one or more types of cells in the body. Genes contain instructions that determine how the body is supposed to look and function. (See Genes and Chromosomes for a discussion about genetics.)
The sex chromosomes determine whether a fetus becomes male or female. A pair of X and Y chromosomes (XY) results in a male, and a pair of X and X chromosomes (XX) results in a female.
Worldwide, Turner syndrome occurs in about 1 out of 2,500 live female births. Almost all affected fetuses miscarry spontaneously.
Symptoms of Turner Syndrome
Some symptoms of Turner syndrome are noticeable at birth. Other symptoms are not noticed until the children are school-age or older.
Infants
Many newborns with Turner syndrome are mildly affected, but some have swelling (lymphedema) on the backs of their hands and tops of their feet. Swelling or loose folds of skin are often evident over the back of the neck.
Heart defects include narrowing of part of the aorta (coarctation of the aorta).
Other common abnormalities seen later include a webbed neck (wide skin attachment between the neck and shoulders) and a broad chest with widely spaced and inwardly turned nipples.
Infants are at a higher risk of a problem with the hip joint called developmental dysplasia of the hip.
Less common symptoms include drooping upper eyelids (ptosis), a low hairline at the back of the neck, moles (nevi), and poorly developed nails.
Older children, adolescents, and women
In most girls, the ovaries are replaced by connective tissue and do not contain developing eggs (gonadal dysgenesis), so these girls are infertile. Gonadal dysgenesis causes a lack of menstrual periods (amenorrhea) and breast development. Girls may not go through the changes of puberty or may not complete puberty. A small number of girls do have a normal puberty and reproductive function.
About 10% of adolescents have scoliosis.
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Other problems may develop. High blood pressure frequently occurs even if the girl does not have coarctation of the aorta. Kidney defects are common.
Occasionally, abnormal blood vessels in the intestine cause bleeding. Hearing loss may occur, and crossed eyes (strabismus) and farsightedness (hyperopia) are common.
Celiac disease, inflammation of the thyroid gland, and diabetes mellitus occur more frequently among girls with Turner syndrome compared to the general population.
Girls with Turner syndrome caused by a certain type of chromosome abnormality are at increased risk of a tumor of the ovaries called gonadoblastoma, which may be cancerous (malignant).
Many girls with Turner syndrome have attention-deficit/hyperactivity disorder and learning disabilities with difficulty assessing visual and spatial relationships, planning tasks, and paying attention. They tend to score poorly on certain performance tests and in mathematics, even if they achieve average or above-average scores on verbal intelligence tests. Intellectual disability is rare.
A girl or woman with Turner syndrome is often short compared with family members, and obesity is common.
Diagnosis of Turner Syndrome
Appearance at birth
Genetic tests
Imaging tests
Doctors may suspect the diagnosis of Turner syndrome if a newborn has lymphedema or a webbed neck. However, they may not suspect the syndrome until adolescence, when the girl is short and has delayed puberty with no periods.
To confirm the diagnosis, doctors do a blood test to analyze the chromosomes.
Doctors do echocardiography or magnetic resonance imaging (MRI) of the heart to detect heart problems and continue to screen for them regularly.
Treatment of Turner Syndrome
Surgical repair of heart defects
Growth hormone therapy
Estrogen therapy
Regular evaluations for other problems
There is no cure for Turner syndrome. However, some specific symptoms and problems caused by the syndrome can be treated.
Coarctation of the aorta is usually repaired surgically. Doctors monitor and repair other heart defects as needed.
Lymphedema can usually be controlled with support hosiery and other techniques such as massage.
Treatment with growth hormone can stimulate growth. Once satisfactory growth has been achieved, treatment with growth hormone is stopped.
Treatment with the female hormone estrogen is usually needed to initiate puberty and is typically given at age 12 to 13 but is usually not started until after satisfactory growth has been achieved. After girls have undergone puberty, they are given birth control pills that contain estrogen and progestin. These medications help girls maintain their female sexual characteristics. Estrogen therapy may also improve the girl’s ability to plan tasks, pay attention, and assess visual and spatial relationships and also helps the bones become dense and helps the skeleton develop properly.
Some girls who have Turner syndrome begin puberty normally without estrogen therapy, but this is more common among girls who are mosaic. Girls who have mosaic Turner syndrome have a mixture of two or more types of cells. Some of their cells contain two or more X chromosomes and some cells contain just one X chromosome. These people with Turner syndrome may become pregnant, and they should use contraception if they are sexually active and want to prevent pregnancy. Fertility may be limited, so if they wish to become pregnant, they usually require alternative fertility interventions.
Girls with Turner syndrome should have regular evaluations to detect problems that may result from this disorder. Evaluations include the following:
Heart examinations
Kidney function tests
Hearing examinations
Bone evaluations (for hip dislocations and scoliosis)
Eye examinations by a pediatric ophthalmologist
Thyroid function tests
Screening tests for celiac disease
Blood tests for glucose (sugar) intolerance (starting at 10 years of age)
