Genetic screening for miscarriage of pregnancy

If there is a history of early pregnancy termination, stillbirths of unknown genesis, or fetal malformations, it is advisable to conduct a genetic examination of the married couple in a medical genetic consultation or specialized laboratory.

Genealogical examination of a married couple is carried out according to the instructions of the Ministry of Health. Married couples with miscarriage often have a burdened pedigree with indication in the anamnesis of close relatives of spontaneous miscarriages, infertility, and the birth of children with developmental anomalies.

Until recently, dermatoglyphics was considered one of the informative methods of research in genetics. Clarification of the features of dermatoglyphics allows us 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 pattern of the palms occurs in the 3rd-4th month of intrauterine development in accordance with chromosomal influences. The 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 uniform features of dermatoglyphics that can be used for diagnostic purposes. An analysis of the skin pattern of the terminal phalanges of the fingers, finger and axial triradii, finger comb count, the end of the main palmar lines, the four-finger groove with its variants is carried out.

According to Henry's classification, three types of patterns are distinguished on the fingers: arcs (simple and tent-shaped), loops (radial, ulnar), and whorls. People with intact reproductive function are characterized by a variety of papillary patterns. The points of contact of three streams of papillary lines, going at an angle of 120 degrees to each other, form three radii. The palms are characterized by the presence of four subdigital triradii, the fifth (proximal) is located near the folds of the wrist. With the help of the triradius, it is possible to distinguish types of skin patterns and count the number of combs from the triradius to the center of the pattern or between two triradii, i.e. to conduct a comb count.

The angle (ATD) formed by connecting the straight lines of the proximal triradius and two subdigital (under the II and IV fingers) is also of diagnostic value. Normally, it is equal to or less than 45°. In dermatoglyphic analysis, it is recommended to conduct studies on both hands. Several methods of quantitative assessment of dermatoglyphic features are used. Quantitative characteristics of dermatoglyphic data include the following indicators: arcs, ulnar loops, radial loops, whorls, ridge palmar and finger count, ATD angle.

In cases of miscarriage, some dermatoglyphic features were revealed: radial loops were found on the fingers more often than in the control. Monomorphic hands along the ulnar loops were observed twice as often as in the control. On the palms, an axial triradius and an ATD angle greater than 60° were more often noted; in cases of miscarriage, an interdigital additional triradius was found 10 times more often. Shortening of the main palmar line was often found. "Pure" forms and variants of the four-finger groove were detected more often than in the control.

Due to the improvement of cytogenetic analysis methods, opportunities have emerged for more accurate analysis of genetic problems, both in the embryo/fetus and in the parents. Dermatoglyphic analysis in this regard is of historical interest and can be used where cytogenetic analysis is not possible.

In almost half of women, the immediate cause of miscarriage is a chromosomal abnormality of the embryo. Miscarriages with structural aberrations are relatively rare, more than half of them are inherited from parents, and do not occur de novo.

During meiosis, a disorder in the distribution of chromosomes rather than their structural integrity often occurs. Diagnostic signs of miscarriages of chromosomal etiology are early pregnancy miscarriages, abortions with an abnormal karyotype, the birth of a child with a chromosomal pathology (Down's syndrome, mental retardation, facial dysplasia), stillbirths, which may be caused by an abnormal set of chromosomes.

Chromosomal abnormalities in the fetus can be present in spouses with a normal karyotype. Conception of a fetus with an abnormal karyotype occurs as a result of a mutation during meiosis or during mitosis disorders. Chromosomal abnormalities can be from parents who are heterozygotes for translocation, inversion, mosaic. Carriers of aberrant chromosomes are phenotypically normal, with the exception of reduced reproductive function. Often, when detecting inversion, translocation of chromosomes, "mosaic" in parents, a geneticist writes a conclusion - a normal variant. For a given person, this may be a normal variant, and until the human genome is completely deciphered, it is very difficult to say what additional chromosome shares or shortening of some arms, etc. mean, but in the process of meiosis - the process of dividing the parental chromosomes into two parts and the subsequent fusion of the two halves of the chromosomes into one, these "mosaics" and inversions can create an abnormal set of chromosomes. Therefore, identifying karyotype pathology, which today is not considered normal but rather a “variant” of the norm, seems especially important if the cause of habitual early miscarriage cannot be identified.

In this regard, we believe that cytogenetic testing of spouses with habitual miscarriage in the first trimester is an important component of the examination. All patients with karyotype features should be informed that prenatal diagnostics is necessary in the event of pregnancy. This is especially relevant for parents over 35 years of age.

An important part of medical genetic counseling is the assessment of the HLA system of the spouses.

It is currently known that each human cell contains 5-6 million genes and each gene is a unique sequence of approximately 1000 nucleotide pairs. The nature of transcription, replication and maintenance of the human genome by each cell is very complex. And so that the nature of the genome is not violated, in the body there are genes in each cell - antigens that track "self" from "foreign" - the main histocompatibility complex, one of the most studied areas of the human genome, which is associated with the genetic control of the human immune response.

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

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