Basic concepts
Shereshevsky-Turner syndrome (Ulrich-Turner) is a genetic disease that is caused by a structural disorder or complete absence of one of the sex X chromosomes.
All information about a person is stored in DNA strands, which are completed into chromosomes. The genome of a healthy person consists of 46 chromosomes, 44 of which form 22 pairs of autosomes that are identical for male and female organisms. The last, 23rd pair of chromosomes, determines whether a person is male or female. In women, these DNA chains are designated as XX, and in men, XY, and the karyotype of a healthy person, as 46 XX or 46 XY. In Shereshevsky-Turner syndrome, the set of chromosomes is recorded as 45X0.
The syndrome got its name in honor of the doctors who first described this disease at the beginning of the 20th century, sometimes the disease is called gonadal dysgenesis, indicating the main symptom of the disease. The disease is rare, according to statistics, the syndrome is detected in 1 out of 3 - 5 thousand newborns. But the true prevalence of the disease in the population is difficult to determine, since the pregnancy of a woman who bears a fetus with genetic defects often ends with self-abortion.
A single X chromosome determines the female sex of a child. But a single nucleoprotein structure cannot provide normal sexual development. In addition, the "dropped out" DNA contains about 5% of all genetic information, a child with this genotype will inevitably have malformations and disruptions in the work of various organs.
There are many genetic syndromes that are accompanied by an excess of chromosomes, an increase in their number. But there is only one disease in which a child “loses” genetic information and remains viable - Shereshevsky-Turner syndrome. With a lack of nonsex chromosomes - autosomes, the fetus is doomed to death due to malformations incompatible with life.
Varieties of pathology
- lack of an X chromosome.
This form is the most severe and common variant (about 60% of cases). It is characterized by the complete absence of the sex chromosome, which leads to a pronounced classic clinical picture. The genetic material is not enough for the full development of the fetus, and starting from 3 months of pregnancy, initially normal ovaries undergo changes. Their structure is replaced by connective tissue, the fetus develops malformations;
- mosaic shape.
This variant of the disease accounts for about 20% of the total number of the disease. The disease proceeds more favorably, since some of the cells have a normal set of chromosomes, which means it compensates for the manifestations of pathology. The appearance of girls with a mosaic form of the disease may correspond to the classic manifestations of the syndrome, although the typical signs are less pronounced. Gross violations in the structure and function of internal organs appear less often, which greatly facilitates the course of the disease;
- violations of the structure of the X chromosome.
20% of patients with hereditary syndrome have an initially normal set of chromosomes, but one of them is distinguished by serious violations of the structure of the molecule. In such cases, women have signs characteristic of the classic form of the disease, but their severity is much less.
The literature describes rare cases of detection of Shereshevsky-Turner syndrome in men. This is due to chromosomal mosaicism, when cells with a different set of DNA molecules are present in the body.
Causes of the disease
The prerequisites for the development of the syndrome arise during the formation of the embryo. One of the chromosomes "falls out" or has an abnormal structure. The causes of the appearance of chromosomal diseases have not yet been sufficiently studied. It is believed that exposure to ionizing radiation, pollution of the environment, illness of parents before conception, and the use of medications increase the risk of having a baby with pathology. But situations of the birth of a baby with a genetic syndrome in absolutely healthy parents are described, which indicates the "accident" of the mutation.
No parents can be 100% sure that they will have an absolutely healthy child. No one is immune from the appearance of a genetic defect, which means that it is very difficult to prevent the disease. In most cases, children with Shereshevsky-Turner syndrome are born to parents with an uncomplicated history.
Sometimes when examining mothers and fathers of a sick baby, signs of "gonadal mosaicism", the simultaneous presence of normal and abnormal sex cells, are found. If a defective gamete was involved in the formation of the embryo, the child has chromosomal diseases.
Research proves that mother's age does not affect the appearance of Shereshevsky-Turner syndrome in a child. Almost all cases of the disease are associated with the loss of paternal DNA molecules.
Symptoms of the disease
Usually, the pathology is determined even in the maternity hospital, the neonatologist pays attention to the characteristic symptoms of the disease and establishes a preliminary diagnosis. The typicality of the clinical picture of the disease is associated with the common for all patients "lost" genetic information in the child, which was in the X chromosome.
Pregnancy of women carrying a baby with a genetic defect is usually difficult. There are frequent cases of toxicosis, threats of termination of pregnancy, premature onset of labor.
Signs of a genetic syndrome in a newborn
- short stature and birth weight.
Even if the baby was born from a full-term pregnancy, his physical development does not meet age standards. The child's body weight rarely exceeds 2500 g, and the body length is 45 cm. In the future, the growth rate of the baby remains reduced, the crumb gains poorly in weight, and the monthly increase does not correspond to the norm;
- wrong physique.
The limbs of the baby look disproportionate to the body, and the chest is wide. The cause of these manifestations is the pathology of the development of the skeletal system, deformation of the bones of the spine, sternum, the horizontal arrangement of the ribs. In a child, you can find anomalies in the development of fingers, shortening of the hands and aplasia of the phalanges, the nails of the crumbs are often flattened, deformed. When examining the oral cavity, the doctor draws attention to the high-positioned "Gothic" palate;
- deformities of the elbow, knee joints.
When trying to straighten the baby's arm and lay it parallel to the body, the doctor may notice an increased angle of deviation from the longitudinal axis. This pathology is called hallux valgus and manifests itself in 40% of cases. Less often, the curvature occurs in the knee joints and significantly worsens the quality of life of the baby, the baby cannot learn to walk for a long time;
- swelling of the feet and hands.
Against the background of the baby's lag in physical development, edematous lower extremities are striking, less often the upper ones. The baby's feet look plump, the skin over them is stretched, this is due to the pathology of the development of the lymphatic vessels of the newborn. The low diameter of the capillaries that discharge the lymph leads to a violation of the outflow of fluid and the development of edema. With age, this symptom becomes more pronounced, the baby spends more time in an upright position, thereby increasing the load on the vessels.
- folds in the neck.
One of the main symptoms that allows one to suspect a genetic syndrome is a pterygoid fold in the neck. It is a membrane of skin cells that connects the area behind the ears to the upper back, the trapezius muscle. The severity of the pathological symptom may be different, but in more than 70% of cases, this defect is found in the baby. In addition, the neck itself looks wide and short, and the baby's hairline is low;
- abnormal ears.
One of the frequent manifestations of various hereditary diseases is the deformation of the auricle. This symptom is not specific for Shereshevsky-Turner syndrome, but in combination with other manifestations confirms the genetic nature of the disease. The baby's ears are located lower than those of other children, protruding, and the auricle itself may be deformed, underdeveloped;
- sexual infantilism.
At an early age, there may be no obvious signs of underdevelopment of the genitals, although gonadal dysgenesis is almost always observed. Due to the lack of sex hormones, the structure of the uterus and ovaries changes, but this cannot be determined without special examination methods. Changes in the external genital organs are manifested by an increase in the size of the clitoris, a narrower entrance to the vagina. A violation in the hormonal background can be indicated by widely located, hypoplastic, inverted nipples, which are determined in 80% of cases of the disease;
- malformations of internal organs.
In addition to external signs indicating the presence of a syndrome in a child, the disease manifests itself in the defeat of internal organs. Often, a child found heart defects and vascular abnormalities of the kidneys, ureters, gastrointestinal tract, sometimes there are lesions of sight and hearing girls;
- general symptoms.
The behavior of a baby in the first year of life may also differ. During feeding, the mother notices sluggish sucking, the baby can vomit out all the food eaten with a fountain. These children are prone to anxiety, cry for no reason. Lagging in mental development is manifested by late mastery of speech skills.
The classic triad of symptoms was described by Turner in 1938, according to an American doctor, the main manifestations of the syndrome are underdevelopment of the reproductive system, deformation of the elbow joints and a pterygoid fold in the neck.
Manifestations of the disease at an older age
As the baby grows up, the symptoms of the disease become more noticeable, new signs of the disease appear:
- developmental lag.
Girls with Turner syndrome Shereshevscky-lag far behind in physical development of their peers, with age, this difference becomes more pronounced. The body weight of children with this genetic syndrome is also not high. Such changes are explained by a disruption in the child's endocrine system, a lack of important hormones.
Mental development in most patients with this syndrome does not suffer. Sometimes there is a slight decrease in cognitive functions, memory, ability to concentrate, associated with a lack of thyroid hormones. Cases of a significant decrease in intelligence, the development of oligophrenia are extremely rare;
- violation of puberty.
The pathology of the reproductive system occurs in almost every patient with this genetic syndrome. A single sex X chromosome cannot ensure the normal development of the reproductive organs.
Ovarian pathology occurs even in utero, when the gonadal tissue is replaced by connective tissue. With such changes, ovulation is impossible; women with Shereshevsky-Turner syndrome very rarely have children. Menstruation occurs in only 5% of patients and is irregular.
The body changes that occur in normal girls during adolescence are associated with increased levels of sex hormones. Patients with genetic syndrome do not have normal puberty. Anomalies in the development of the mammary glands are manifested in a slight increase in the breast, a violation of the shape and paleness of the nipples. Hair growth is markedly insignificant, sometimes the hairline appears in places characteristic of men (arms, upper lip, chest). Internal genital organs: the vagina, uterus and fallopian tubes are also insufficiently developed;
- hyperpigmentation.
Violation of the endocrine glands leads to an increase in the formation of melanin pigment in the skin. Patients are characterized by the appearance of moles, age spots, which usually appear in childhood. Over time, their number and size may increase. In some patients, there is a general darkening of the skin, the woman looks dark;
- somatic diseases.
Malformations of internal organs lead to a violation of their function, the development of renal, cardiovascular failure. It is not uncommon for women with the genetic syndrome to suffer from hypertension. Possible variants of the course of the disease, which are accompanied by hearing loss, visual impairment, diseases of the osteoarticular apparatus, diabetes mellitus, hypothyroidism. Deformations auricles curving teeth on the neck skin fold considered as a cosmetic defect and corrected through surgery.
Diagnostics
Usually, the syndrome is determined after birth, when the doctor notices changes in the baby's appearance characteristic of the disease. But a geneticist can suspect the possibility of a disease even before pregnancy. Therefore, the diagnosis of genetic syndromes should consist of several stages.
Medical and genetic counseling
If parents in families there were cases of the birth of a child with hereditary pathology, during pregnancy planning is necessary to consult with a physician-geneticist. The risk of developing the disease and fall women with a history there have been cases samoabortov place that may indicate the presence of a genetic defect in the fetus incompatible with life. To clarify the parents' genome, karyotyping is carried out, in which the quality and number of chromosomes is examined.
Screening research
Ultrasound and blood tests for specific markers are widely used to diagnose genetic diseases.
The timing in which the doctor recommends to undergo an examination is not accidental. It was at this time that specific signs of pathology in the fetus and changes in the blood test can be noticed. Assessing the research results in a complex, the doctor determines the further tactics of managing a pregnant woman.
Invasive methods
At high risk of birth of a baby with a woman should undergo pathology studies such as amniocentesis, cordocentesis, chorionic villus sampling. With the help of these methods, it is possible to obtain genetic material from a child and accurately determine its karyotype.
Although these methods are reliable in 99% of cases, their use is limited due to the risk of complications - termination of pregnancy, which occurs in 1% of patients.
Survey baby after birth
Diagnosis of ailment after the birth of a baby includes:
- collection of anamnesis.
When talking with parents, the doctor clarifies whether there have been cases of hereditary diseases in the family, what factors influenced the course of pregnancy. But these signs are not specific, a sick child can be born to absolutely healthy parents;
- inspection.
The characteristic symptoms of the disease can be detected already in the first minutes of a baby's life. This occurs in the classical course of the disease, when the diagnosis of the disease is not difficult. In the case of the mosaic form of the syndrome, the external manifestations are not very pronounced, often the girl's problems arise during puberty;
- karyotyping.
A cytological study of the structure and number of chromosomes will help to confirm the doctor's suspicions.The method is simple to perform (it is enough to take a blood test), and its reliability is very high. The karyotype of a child, recorded as 45X0, speaks of Shereshevsky-Turner syndrome in a baby;
- laboratory and instrumental methods.
These studies will help to detect the pathology of internal organs, in time to notice a violation of their function. It is recommended to comprehensively examine the baby, conduct an ultrasound, ECG, X-ray of the bones of the feet and hands, spine, blood and urine tests;
- consultation of specialists.
After the birth of the baby, a geneticist will help to confirm the diagnosis. In the future, depending on the clinical manifestations of the disease, the baby may need to consult a cardiologist, nephrologist, gynecologist, surgeon, traumatologist, endocrinologist and other specialists.
Treatment
Therapy of the syndrome is aimed at restoring the function of the affected organs, stimulating the growth of the child, and sexual development. Babies with a genetic disease receive nonspecific treatment that helps to accelerate the pace of physical development - massage, gymnastics, vitamin therapy, proper nutrition.
In preschool age, when the rate of development of the girl decreases, the endocrinologist prescribes injections of growth hormone - somatotropin. Daily subcutaneous injections of the drug help accelerate the growth of the child, increase the patient's final height to 150 - 155 cm. Usually, growth hormone is prescribed in combination therapy with anabolic hormones. Drugs such as oxandrolone can help your child gain muscle mass.
During puberty, it is recommended to use estrogen replacement therapy. Under the influence of these hormones, the formation of secondary sexual characteristics, the growth of the uterus and mammary glands occurs. Menstruation may occur, but fertility in women with the genetic syndrome is drastically reduced due to gross changes in the ovaries.
The volume and duration of hormone therapy is determined only by an endocrinologist. Inappropriate treatment can aggravate a child's hormonal imbalance.
Diseases of the internal organs that accompany the manifestations of the syndrome are treated individually. In the presence of gross defects, surgical treatment is often required, long-term dispensary monitoring of the baby's health by many specialists.
Recently, the IVF method has become increasingly popular, with the help of which a fertilized egg is transferred into the uterus of a woman with Shereshevsky-Turner syndrome. For these purposes, a donor oocyte is better suited than an egg from a sick woman, since there remains a high risk of developing fetal malformations.
Forecast and prevention
In the absence of gross malformations, women with the genetic syndrome live long lives, create families, and become sufficiently socialized. The quality of life is also greatly influenced by the adequacy of the treatment, which can significantly reduce the symptoms of the disease.
Preventive measures include medical and genetic counseling of families who are at risk for the development of hereditary pathology, examination of a woman during pregnancy.
Conclusions
Genetic diseases are rare, but their feature is a combination of pathology of various organs and systems, characteristic external manifestations. There are many reasons for the development of mutations in the genotype, and it is not always possible to find a factor that influenced the appearance of abnormalities in a child. No family is immune from the appearance of a baby with a genetic defect.
Parents of a child with Shereshevsky-Turner syndrome need to understand that correct, timely treatment started significantly improves the quality of life of the baby and reduces the severity of the main symptoms. In general, the prognosis for this disease is favorable, children with a genetic defect are able to socialize in society, get a higher education, and live a long life.
