The Turner syndrome occurs in approximately one in every 2000 – 4000 women born alive, is a chromosomal condition that describes girls and women with common characteristics, physical features and medical conditions caused by the complete or partial absence of the second sex chromosome. It was first described in the United States in 1938 by Dr. Henry Turner.
At the basic level, missing genetic material prevents the female body from growing and maturing naturally, Turner syndrome is variable, and each girl and woman will have unique health characteristics and needs. Most have two complete X chromosomes (the sex chromosomes for women). It is caused by the absence of all or part of the second sex chromosome in some or all of the cells of the body, the most consistent characteristics are short stature and lack of ovarian development, however, there are other symptoms and characteristics that can appear in varying degrees, depending on the unique genetic makeup of each person.
What is Turner syndrome?
Also known as 45, X or 45, X0, it is a chromosomal condition that alters development in women and where they tend to be shorter in size than average and generally cannot conceive a child (infertile) due to the absence ovarian function. Other characteristics of this condition that can vary among women who have Turner syndrome include: extra skin on the neck (webbed neck), swelling or swelling (lymphedema) of the hands and feet, skeletal abnormalities, heart defects, and kidney problems.
Turner syndrome occurs when part or all of one of your X chromosomes is missing, people with it can lead healthy lives but generally require constant and constant medical supervision to detect and treat complications. There is no way to prevent it, and the cause of the genetic abnormality is unknown.
Researchers have not yet determined which genes on the X chromosome are responsible for most of the signs and symptoms of Turner syndrome, but they have identified a gene called SHOX that is important for bone growth and development.
Symptoms of Turner syndrome
Signs and symptoms vary considerably, and can even appear before birth, including lymphedema, which occurs when fluid is not adequately transported around the fetus’s body organs, and excess fluid leaks into the surrounding tissue, resulting in that produces swelling.
Of the following common symptoms, a person can have any combination and is unlikely to have all of the symptoms.
- Short stature.
- Lymphedema (swelling) of the hands and feet of a newborn.
- Wide chest and widely spaced nipples.
- Low back hair.
- Low ears.
- Reproductive sterility.
- Gonadal streak of rudimentary ovaries (underdeveloped gonadal structures that later become fibrotic).
- Amenorrhea, the absence of a menstrual period.
- Weight gain, obesity.
- Short pastern IV.
- Small nails.
- Characteristic facial features.
- Palmate neck of cystic hygroma in childhood.
- Aortic valve stenosis.
- Bicuspid aortic valve (most common heart problem).
- Horseshoe kidney.
- Visual impairments: sclera, cornea, glaucoma, etc.
- Ear infections and hearing loss.
- High waist-to-hip ratio (hips are not much larger than waist).
- Attention deficit hyperactivity disorder (problems with concentration, memory , attention with hyperactivity seen mainly in childhood and adolescence).
- Non-verbal learning disability (problems with mathematics, social skills, and spatial relationships).
Other features may include a small lower jaw (micrognathia), cubitus valgus, soft upturned nails, palmar crease, and drooping eyelids, less common are pigmented moles, hearing loss, and a high arched palate (narrow jaw). Turner syndrome manifests itself differently in each woman affected by the condition; therefore, no two people share the same characteristics.
While most physical findings are harmless, significant medical problems can be associated with the syndrome, most of these important conditions can be treated with surgery and medications.
Despite the excellent postnatal prognosis, it is believed that 99% of Turner syndrome conceptions end in miscarriage or fetal death and up to 15% of all miscarriages have the 45, X karyotype. Routine amniocentesis or chorionic villus sampling, one study found that the prevalence among evaluated pregnancies was 5.58 and 13.3 times higher, respectively, than among live newborns in a similar population.
The rate of cardiovascular malformations among patients with Turner syndrome ranges from 17% to 45%. The variations found in the different studies are mainly attributed to variations in the non-invasive methods used for screening and the types of lesions that they can characterize. However, it could simply be attributable to the small number of subjects in most studies.
Different karyotypes can have different rates of cardiovascular malformations. Two studies found a cardiovascular malformation rate of 30% and 38% in a group of 45, X pure monosomy, considering other karyotype groups, reported a prevalence of 24.3% and 11% in people with mosaic X monosomy, and a rate of 11% in people with structural X chromosomal abnormalities.
The higher rate in the 45, X pure monosomy group is primarily due to a difference in the rate of aortic valve abnormalities and coarctation of the aorta, the two most common cardiovascular malformations.
Normal skeletal development is inhibited due to a wide variety of factors, mostly hormonal, the average height of a woman with Turner syndrome, in the absence of hormone treatment, is 4 feet 7 inches (140 cm).
The fourth metacarpal bone (fourth and ring finger) can be unusually short, as can the fifth.
Due to the inadequate production of estrogen, many of those who suffer from Turner syndrome develop osteoporosis, this can further decrease the height and aggravate the curvature of the spine, which can lead to scoliosis, it is also associated with increased risk of bone fractures.
About a third of all women with Turner syndrome have one of three kidney abnormalities:
- A single horseshoe-shaped kidney on one side of the body.
- An abnormal urine collection system.
- Poor blood flow to the kidneys.
Some of these conditions can be corrected surgically. Even with these abnormalities, the kidneys of most women with Turner syndrome function normally. However, as noted above, kidney problems can be associated with hypertension.
About a third of all women with Turner syndrome have a thyroid disorder, usually hypothyroidism, specifically Hashimoto’s thyroiditis. If detected, it can be easily treated with thyroid hormone supplements.
Women with Turner syndrome have a moderately elevated risk of developing type 1 diabetes in childhood and a substantially increased risk of developing type 2 diabetes in the adult years. The risk of developing type 2 diabetes can be substantially reduced by maintaining a healthy weight.
Turner syndrome does not usually cause intellectual disability or affect cognition, however learning difficulties are common among women with the syndrome, in particular, a specific difficulty in perceiving spatial relationships, such as non-verbal learning disorder, this It can also manifest as a difficulty with motor control or with mathematics. Although it is not correctable, in most cases it does not cause difficulty in daily life.
Women with Turner syndrome can experience adverse psychosocial outcomes. Research shows a possible association between age at diagnosis and increased substance use and depressive symptoms.
Women with Turner syndrome are almost universally infertile, some women have become pregnant and have had full-term pregnancies, this is very rare and generally limited to those women whose karyotypes are not 45, X, even when such pregnancies do occur, there is a higher than average risk of miscarriage or birth defects, including Turner syndrome or Down syndrome . Some women who cannot conceive without medical intervention can use IVF or other fertility treatments.
Causes and risk factors of Turner syndrome
Most people are born with two sex chromosomes, men inherit the X chromosome from their mothers and the Y chromosome from their fathers, and women inherit one X chromosome from each father.
When a woman has this disorder, one copy of the X chromosome is absent or significantly altered. Various genetic alterations are possible.
Monosomy: An X chromosome is missing entirely, experts believe this is caused by an error in the father’s sperm or the mother’s egg. Every cell in the offspring’s body has a missing X chromosome.
Mosaic Turner syndrome, also called mosaicism or Turner mosaicism: During the early stages of fetal development, an error in cell division can occur, causing some cells to have two copies of the X chromosome, while others have only one.
Y chromosome material: A small number of people with the disorder have some cells with only one copy of the X chromosome, and others with only one copy of the X chromosome and some Y chromosome material. The individual develops as a woman but with an increased risk of developing a type of cancer known as gonadoblastoma.
The loss or abnormality of the X chromosome occurs spontaneously at conception when the egg is fertilized, the missing or altered X chromosome causes errors during fetal development and in development after birth. Having a child with the disorder does not increase the risk of having other children with the disease.
Complications of Turner syndrome
Some of the medical complications that may need to be considered include:
- Congenital heart defect: The various structures of the heart may not develop normally in the uterus, some of these are corrected, others need surgery.
- Hearing problems: Women with Turner syndrome can have some deafness caused by ear infections in childhood, they can also develop nerve deafness caused by degeneration of the auditory nerves.
- Middle ear infection (otitis media): Girls with Turner syndrome are more vulnerable to ear infections because their tubes are narrower than normal.
- High blood pressure (hypertension): This occurs most often in adolescent and adult women, it can be caused by a narrowing (coarctation) of the aorta (a main artery), which can be repaired surgically. However, no reason can be found for the increased pressure.
- Kidneys: An ultrasound may show some structural abnormalities in the kidneys, but these differences generally do not affect the function of the kidneys.
- Thyroid function and diabetes: There is an increased rate of type II diabetes and thyroid gland disorders in women with Turner syndrome.
How can Turner syndrome be diagnosed?
It is most commonly diagnosed during fetal life, in infancy, during the late pre-adolescent period (8-12 years), or in late adolescence / early adulthood. The age of diagnosis has decreased with better awareness in the medical community.
Usually there is something “different” about the girl or woman that prompts the father or doctor to investigate the possibility of this syndrome.
The final diagnosis is made by a blood test, called a karyotype, which examines an individual’s complete set of chromosomes, which determines if one of the X chromosome pairs is missing from the complete chromosome set, or if there are structural differences in the X chromosomes.
Before birth, a diagnosis can be made by a maternal serum examination, taking a sample of amniotic fluid or other fetal tissue to look at the fetal karyotype, or an ultrasound, because ultrasound and maternal serum (blood tests ) are not 100% reliable, genetic karyotype testing is essential after the baby is born in order to make confirmation.
There are a variety of health, developmental, social, and learning problems that can affect girls and women to varying degrees, so it is important to diagnose them as early as possible. Early diagnosis helps doctors determine if the girl or woman has health problems that require treatment or care.
What is the treatment for Turner syndrome?
During childhood and adolescence, girls may be under the care of a pediatric endocrinologist, who is a specialist in the childhood conditions of hormones and metabolism.
The injections of growth hormone are beneficial in some people, as they begin in early childhood and can increase final adult height are within a few inches.
The therapy estrogen replacement usually begins at the time of normal puberty, around 12 years to start developing breasts. Estrogen and progesterone are given a little later to start a monthly “period”, which is necessary to keep the uterus healthy, estrogen is also given to prevent osteoporosis.
Babies born with a heart murmur or narrowing of the aorta may need surgery to correct the problem. A heart expert (cardiologist) will evaluate and follow up on any necessary treatment.
Girls who have Turner syndrome are more likely to get middle ear infections, which can lead to hearing loss and should be evaluated by their pediatrician.
Regular health check-ups are very important, special clinics for the care of girls and women are available in some areas, with access to a variety of specialists, so early preventive care and treatment are very important. Almost all women are infertile, but pregnancy with donor embryos may be possible.
Having the proper medical treatment and support allows a woman with Turner syndrome to lead a normal, healthy, and happy life.
Caution and personal care
- Regular check-ups help improve the length and quality of life of the patient.
- There are particular problems that require a specialist such as hearing loss, high blood pressure, osteoporosis, eye problems, and diabetes.
- It is important to be under the close supervision of a cardiologist because heart problems are common in those with Turner syndrome.
- It is important to have healthy lifestyle habits, including a balanced diet and regular exercise.
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