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Genetic examination for miscarriage

 
, medical expert
Last reviewed: 19.10.2021
 
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If there is an abortion in the anamnesis in the early periods, stillbirths of unknown origin, malformations of the fetus, it is advisable to carry out a genetic examination of the couple in the conditions of medical genetic counseling or a specialized laboratory.

Genealogical examination of a married couple is conducted according to the instructions of the Ministry of Health. In married couples with miscarriages, a family tree with a history of close relatives of spontaneous miscarriages, infertility, the birth of children with developmental anomalies is often revealed.

Until recently, one of the informative methods of research in genetics was considered dermatoglyphics. The elucidation of the peculiarities of dermatoglyphics makes it possible to determine the most informative set of deviations in the structure of the skin pattern of the fingers and palms of a person. The formation of each figure of the palms occurs on the 3-4th month of intrauterine development in accordance with the chromosomal influences. Features of the patterns are due to the influence of the parents' genes or chromosomal aberrations in the fetus. In a number of diseases, there are similar features of dermatoglyphics, which can be used for diagnostic purposes. An analysis is made of the skin pattern of the terminal phalanges of the fingers, finger and axial triradius, digital scallop count, the termination of the main palmar lines, the four-finger groove with its variants.

On the fingers of the brush, according to Henry's classification, there are three types of patterns: arcs (simple and hipped), loops (radial, ulnar), curls. For people with intact reproductive function, a variety of papillary pattern is characteristic. The points of contact of three streams of papillary lines, going at an angle of 120 degrees. Each other, form three radii. Palms are characterized by the presence of four subalic triradius, the fifth (proximal) is located near the folds of the wrist. Using triradius, it is possible to distinguish types of skin patterns and count the number of combs from triradius to the center of the pattern or between two three radii, i.e. Hold a scallop.

Diagnostic value also has an angle (ATD), formed as a result of the connection by the straight lines of the proximal triradius and two sub-finger (under the II and IV fingers). Normally, it is equal to or less than 45 °. In dermatoglyphic analysis, it is recommended that the study be performed on both hands. Several methods of quantitative evaluation of dermatoglyphic features are used. The quantitative characteristics of dermatoglyphic data include the following indices: arcs, ulnar loops, radial loops, curls, crestal palm and finger count, angle of ATD.

When miscarriage occurs, some features of dermatoglyphics are revealed: radial loops are found on the fingers of the hand more often than in the control. Monomorphic arms along the ulnar loops are observed twice as often as in the control. On palms more often there is an axial triradius and an angle of ATD more than 60 °, with miscarriages 10 times more often an interdigital additional triradius. Often find a shortening of the main palmar line. More often than in the control, "clean" forms and variants of the four-finger sulcus are revealed.

In connection with the improvement of methods of cytogenetic analysis, it became possible to more accurately analyze genetic problems, both in the embryo / fetus and in the parents. Dermatoglyphic analysis in this regard is more of a historical interest and can be used where there is no possibility of cytogenetic analysis.

Almost half of the women's immediate cause of miscarriage is the chromosomal abnormality of the embryo. Miscarriages with structural aberrations are relatively rare, more than half of them are inherited from parents, rather than de novo.

In the process of meiosis, a disruption in the distribution of chromosomes occurs, rather than their structural integrity. Diagnostic signs of miscarriages of chromosomal etiology are miscarriages of early pregnancy, abortus with an abnormal karyotype, the birth of a child with chromosomal pathology (Down's disease, oligophrenia, facial dysplasia), stillbirths that can be caused by an abnormal set of chromosomes.

Chromosomal abnormalities in the fetus may be in spouses with normal karyotypes. Conception of the fetus with an abnormal karyotype occurs as a result of mutation in the process of meiosis or in the course of mitotic disorders. Chromosomal abnormalities can be from the parents of heterozygotes by translocation, inversion, mosaic. Carriers of aberrant chromosomes are phenotypically normal, with the exception of reduced reproductive function. Often, revealing from parents the inversion, the translocation of chromosomes, the "mosaic", the geneticist writes a conclusion - a variant of the norm. For a given person, this can be a norm option, and until the human genome is completely unraveled, it is very difficult to say what additional chromosome fractions or shortening of some shoulders etc. Mean, but in the process of meiosis - the process of dividing the parent chromosomes into two parts and the subsequent fusion of the two halves of the chromosomes into one, these "mosaics" and inversions can create an anomalous set of chromosomes. Therefore, revealing the pathology of the karyotype, which today is not regarded as a norm, but as a "variants" of the norm, seems to be important especially if the cause of the habitual miscarriage of early terms can not be identified.

In this regard, we believe that the cytogenetic study of spouses with a habitual miscarriage of pregnancy of the first trimester is an important part of the survey. All patients with karyotype characteristics should be informed that prenatal diagnosis is necessary in case of pregnancy. This is especially true for parents over the age of 35.

An important component of medical genetic counseling is the evaluation of the HLA system of spouses.

It is now known that each human cell contains 5-6 million genes and each gene represents a unique sequence of approximately 1000 nucleotide pairs. The nature of transcription, replication and preservation of the human genome by each cell is very complex. And that the nature of the genomane is broken, in the body there are genes in every cell - antigens that track their "own" from "alien" - the main complex of histocompatibility, one of the most studied areas of the human genome, which is linked to the genetic control of the human immune response.

The main histocompatibility complex encodes the HLA system. Antigens of the HLA system can be determined by serological testing methods (class I HLA-A-B-C) and genetic DNA-based polymerase chain reaction (class II DR, DQ DP).

trusted-source[1], [2], [3], [4]

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