Turner syndrome: Description
Turner syndrome is also known as monosomy X. It occurs in one in 2,500 newborns. Women with Turner syndrome lack functioning ovaries. Turner syndrome is called a syndrome because there are several signs of the disease that occur at the same time and are related. It is also referred to as a symptom complex.
The Turner syndrome symptoms were described as early as 1929 by the German pediatrician Dr. Otto Ullrich and in 1938 by the American physician Dr. Henry Turner. Therefore, the name Ullrich-Turner syndrome (UTS) is also used for the disease. However, it was not until 1959 that the missing sex chromosome was found to be the cause.
Monosomy X is relatively common. It is thought to cause one in ten spontaneous abortions in the first trimester of pregnancy. Overall, 99 percent of fetuses with chromosome set “45, X0” die during pregnancy.
Turner syndrome: symptoms
Patients with Turner syndrome are always female. Turner syndrome features are diverse and do not always occur completely in all female patients. They are also age-dependent, meaning that some symptoms appear before or shortly after birth, while other signs only appear later in life.
At all stages of life, Turner syndrome patients often have
- shortened metacarpals
- a low-set hairline and a widened skin fold on the side between the neck and shoulders (wing fur, pterygium colli)
- Malformations of internal organs: e.g. heart defects (e.g. aortic stenosis, atrial septal defect) or kidney malformations (e.g. horseshoe kidney)
Age-related Turner syndrome symptoms.
Newborns are often conspicuous for lymphedema of the dorsum of the hands and feet. These are fluid collections in the skin caused by defective lymphatics.
Infants with Turner syndrome often have the following symptoms:
- broad and flat chest (shield thorax) with widely spaced nipples
- many moles (nevi)
- incipient osteoporosis (bone loss)
In adolescence, the underactivity of the ovaries becomes noticeable. If ovaries are present, they continue to regress. In most cases, however, only strands of connective tissue (streak gonads) are present from the beginning. As a result, puberty does not occur.
Girls with Turner syndrome do not have menstrual bleeding. Doctors then also speak of primary amenorrhea.
Other Turner syndrome characteristics
Other signs that may occur with Turner syndrome include:
- Ear malformations
- Hearing loss
- Underdeveloped (hypoplastic) genitalia
Turner syndrome: Causes and risk factors
Turner syndrome: Explanation of terms
In order to better understand Turner syndrome, here are some explanations of terms.
Turner syndrome is based on a chromosomal aberration. Doctors understand this to mean that the number or structure of the chromosomes is disturbed.
Our genetic information is stored on the chromosomes. Normally, there are 46 chromosomes in each cell. These include two sex chromosomes. In the female karyotype (set of chromosomes) they are called XX, in the male they are called XY.
A normal karyotype is described as 46, XX and 46, XY respectively. If one chromosome is missing, it is called a monosomy.
Turner syndrome: different karyotypes
Different karyotypes can lead to Turner syndrome:
- 45, X0: About 50 percent of affected individuals have only 45 instead of 46 chromosomes in all body cells. In this case, one sex chromosome (X or Y) is missing. This is called monosomy X.
- 45, X0/46, XX or 45, X0/46, XY: More than 20 percent of patients have both cells with a complete set of chromosomes (46, XX) and cells with monosomy X (45, X0). This is referred to as mosaicism
- 46, XX: About 30 percent of affected individuals have a complete set of chromosomes (46, XX) in all cells, but one X chromosome is structurally altered
How does monosomy X develop?
Parents of a child with Turner syndrome do not have an increased risk that another child will also develop the disease. In addition, the age of the mother is not considered a risk factor for developing Turner syndrome.
Turner syndrome: examinations and diagnosis
Turner syndrome can be diagnosed at different times. Often, young children are the first to be noticed due to their short stature, so the pediatrician will order further examinations. As the condition progresses, gynecologists and human geneticists also play a role.
If your pediatrician suspects Turner syndrome, he will first ask you in detail about your medical history. He may ask the following questions, among others:
- Are there any known hereditary diseases in your family?
- Has your child always been smaller than playmates of the same age?
- Did you notice swollen hands or feet in your baby at birth?
Turner syndrome: physical examination
The main focus of the physical examination for Turner syndrome is inspection. The pediatrician looks closely at individual body parts and looks for abnormalities such as short metacarpals, wing fur (pterygium colli), moles (nevi), chest shape, nipple spacing and body size.
Turner syndrome: blood test
After a blood sample is taken, various hormone levels can be determined in the laboratory. Patients with Turner syndrome usually have high FSH and LH levels and very little estrogen in their blood.
In addition, the blood cells taken can be viewed under a microscope and the number as well as structure of the chromosomes can be analyzed. In this way, monosomy X can be easily detected because instead of two sex chromosomes, there is only one.
Turner syndrome: prenatal examinations
With the help of prenatal examinations (prenatal diagnostics), Turner syndrome can already be detected in children in the womb. This can be done with invasive procedures such as amniocentesis or chorionic villus sampling. The disadvantage of these procedures, however, is an increased risk of miscarriage, because an intervention on the part of the pregnant woman is required to take the sample (removal of amniotic fluid or a sample of the placenta).
Non-invasive prenatal blood tests (NIPT) such as the Harmony test, Praena test and Panorama test do not have this disadvantage. These tests only require a blood sample from the pregnant woman. Traces of the child’s genetic material can be found in it, which can be examined for chromosomal abnormalities such as Turner syndrome. The test result is quite reliable.
Turner syndrome: Treatment
In order to treat short stature, therapy with growth hormones should be started in infancy. In this way, an increase in length of 5 to 8 centimeters can be achieved. To achieve this, the growth hormone must be injected daily into the subcutaneous fatty tissue (subcutaneously).
At the age of twelve to 13, puberty should be initiated with medication by an experienced pediatric endocrinologist or pediatric gynecologist. For this purpose, estrogen preparations are taken daily for six to 18 months. A normal four-week cycle is then established in which deri weeks of estrogens are taken, followed by a one-week pause.
The short stature and lack of puberty are often very stressful for Turner syndrome patients, so the above therapies can improve well-being. In addition, estrogens help to counteract early-onset osteoporosis.
Turner syndrome: disease course and prognosis
The karyotype underlying Turner syndrome influences symptom expression and prognosis to some extent:
Patients who have a mixed karyotype with Y chromosome components (45, X0/46, XY) are at risk of ovarian (gonadal) degeneration to gonadoblastoma. Precautionary removal of the ovaries should be considered in these patients.
Patients with a mosaic chromosome set may have normal puberty with a regular menstrual cycle. Pregnancy is then possible.
Turner syndrome: risk for other diseases
In adulthood, Turner syndrome patients have an increased risk of developing
- high blood pressure (arterial hypertension)
- diabetes mellitus
- Obesity (adiposity)
- Osteoporosis (frailty of the bones)
- Thyroid disease (Hashimoto’s thyroiditis)
- Bleeding of the digestive tract (gastrointestinal bleeding)
to fall ill. Therefore, regular health checks should be performed to detect and treat the diseases as early as possible.
Turner syndrome: Pregnancy
If pregnancy is possible, the risk to the life of mother and child should be discussed with an experienced gynecologist. During pregnancy, a Turner woman has a 100-fold higher risk of suffering a rupture of the aorta (aortic rupture or dissection) compared to healthy women.
