Future parents on reception at the geneticist of
the Geneticist are a doctor who is engaged in studying of hereditary diseases. Ideally the office of this doctor needs to be visited during preparation for pregnancy. If future parents of it did not make, then the married couple needs to address the geneticist when there is an increased risk of the birth of the child with hereditary pathology.
It is enumerable those circumstances which can become the reason for the request for consultation to the geneticist.
- the child`s birth with hereditary diseases or malformations;
- presence at one of spouses of a hereditary disease or malformation;
- kinship marriage;
- the age of mother is more senior than 35 years, the age of the father is more senior than 40 years;
- an adverse effect of factors of environment in early terms of pregnancy;
- existence of spontaneous abortions, still births;
- threat of interruption of pregnancy from early terms;
- reception of medicines in early terms of pregnancy.
After conversations with future parents and receiving results of analyses the doctor - the geneticist determines degree of genetic risk for each concrete family. The genetic risk is a probability of emergence of a certain hereditary pathology at addressed for consultation or at his descendants. It is defined by the calculations based on the analysis of genetic regularities, or by means of these carried-out analyses. An opportunity to calculate genetic risk depends generally on the accuracy of the diagnosis and completeness of the genealogical data (given about families of spouses) therefore the married couple has to be prepared for consultation: to remember what serious illnesses relatives of the husband and the wife had.the Genetic risk to 5% is estimated by
as low. The risk from 6 to 20% is considered to be as an average; in this case recommend application of methods of prenatal diagnostics. The risk more than 20% is considered high, application of methods of prenatal diagnostics is strictly obligatory.
Depending on character of a disease at consultation use various methods of inspection of the patient and his relatives, are basic of which clinic - genealogical, cytogenetic, biochemical, immunological, molekulyarno - genetic (DNA - the analysis), methods of prenatal diagnostics.
of Kliniko - a genealogical method , or the method of collecting and the analysis of a family tree, gives necessary information for statement of the diagnosis or establishment of a cause of illness.
the Cytogenetic method allows to study a set of chromosomes of the person (karyotype) directly. Definition of a karyotype is appointed to parents of children with malformations and intellectual backwardness; to the women suffering from the pregnancy not incubation having in the anamnesis of the deadborn or died of not clear reasons children at early age; to women with primary amenorey (lack of periods).
Methods of prenatal diagnostics
Introduction of methods of prenatal diagnostics considerably increased efficiency of the physician - genetic consultation and allowed to pass from health of posterity, probabilistic to the unambiguous forecast. Apply two groups of methods of prenatal diagnostics - noninvasive and invasive.
- of Noninvasive (not surgical) methods prenatal diagnostics is an ultrasonic research in I and II trimesters, definition an alpha - a fetoproteina, a horionichesky gonadotrophin and not conjugated estriol in serum of blood of mother in the II trimester of pregnancy, identification of pre-natal infection. They can be used at inspection of all pregnant women.
a Specific place in prenatal diagnostics is held by ultrasonic research (ultrasonography) . There is an accurate dependence between nature of defect and term of its identification by means of ultrasonography. A number of malformations can be diagnosed at the end of I - the beginning of the II trimester of pregnancy. Among them - the rough defects of a brain, extensive hernias of a forward belly wall which are not divided fruits, cherepno - brain and spinal hernias, polikistoz kidneys, etc. Accuracy of diagnosis of these malformations by the end of the II trimester of pregnancy approaches 100%. Accuracy of diagnostics of congenital defects of a fruit makes 87%, in group of the increased risk - 90%.the accurate organization of ultrasonic inspection is necessary for
For timely diagnosis of congenital malformations of a fruit: it all need to carry out pregnant not less than 3 times during pregnancy (in 10 - 12, 20 - 22 and 30 - 32 weeks), and according to indications (the anamnesis or suspicion on a malformation) - is more often (every 3 - 4 week) and with careful research of all bodies and systems of a fruit.by
Definition an alpha - the fetoproteina (biologically active agent which is produced a placenta) and other markers in serum of blood of the woman is made on 16 - 20 - y to week of pregnancy.to
contents Change an alpha - the fetoproteina in serum of blood of pregnant women gives the chance to distinguish from them women with risk of development of defect of nervous system of a fruit (crevices of a spinal cord, an anentsefaliya - lack of a brain), with risk of developing of chromosomal pathology. Further the diagnosis is specified by means of ultrasonography and definition an alpha - a fetoproteina in amniotic waters.
- by means of of invasive (surgical) methods are received by fruit cages for different types of the analysis.
In early terms of pregnancy to prenatal diagnostics applies by a biopsy of a horion . Make a puncture of a forward belly wall, a fetal bubble for receiving a small site of a horion (the placenta is formed further of it). For performance of this procedure the term of 8 - 11 weeks of pregnancy is optimum. Receiving fabric of a horion is necessary in the following cases:
- change of a karyotype (set of chromosomes) at one of parents;
- the age of mother is more senior than 35 years;
- existence in the child`s family with chromosomal pathology, the diseases linked to a floor (for example, hemophilia), metabolic disorders, gemoglobinopatiya.
Sometimes as diagnostic material use the placenta fabric received by means of of a platsentotsentez (research, similar to a biopsy of a horion) in the II trimester of pregnancy. Indications to carrying out a platsentotsentez the same, as to a biopsy of a horion.
Amniotsentez (a fence and the analysis of amniotic waters) in the II trimester of pregnancy as the method of prenatal diagnostics was widely adopted most. For its carrying out the term of 17 - 20 weeks of pregnancy is optimum. At research of amniotic liquid it is possible to define a fruit karyotype, level of content of various enzymes, hormones, an alpha - a fetoproteina; to carry out the analysis of DNA and thus to diagnose chromosomal pathology of a fruit, some autosomno - the recessive and inherited diseases linked to a floor, malformations of the central nervous system.
Receiving blood of a fruit from umbilical cord vessels - kordotsentez . It can be seen off since 17 - y weeks of pregnancy. Investigating fruit blood, it is possible to diagnose hereditary immunodeficiency, blood diseases, pre-natal infection of a fruit, exchange violations, to define a karyotype (set of chromosomes) of a fruit.In the II trimester of pregnancy carrying out a biopsy of skin of a fruit which is carried out for the purpose of prenatal diagnosis of some diseases of skin is possible
. At the same time it should be noted that there is a so-called technique of an embrioskopiya (from Greek embryon - a germ, skopeo - I look), applied in the I trimester of pregnancy. For its carrying out the special flexible fiber optics is used: the fiber-optical endoscope is entered into a uterus neck. This procedure can be carried out not earlier than in five weeks after conception. Thus it is possible to estimate blood circulation of a fruit and to directly observe a condition of an embryo for diagnosing of various violations of its development.
Invasive methods of diagnostics can have various complications, up to pregnancy interruption. Therefore they are applied only when the risk of developing of malformations of a fruit is rather high.