Genomic and structural abnormalities of the chromosome set of the fetus, depending on the age of pregnant women

Abstract

To study the frequency and spectrum of fetal chromosomal abnormalities in pregnant women, depending on age, a cytogenetic study of 2248 biopsies of the chorion and placenta, cord blood lymphocytes and amniocytes was carried out in 2016-2020. The work used the generally accepted methods of direct preparation of chromosome preparation and methods of cell cultivation. The analysis of the preparations was performed based on GTG, CBG staining method and FISH method, using DNA probes for centromeric regions 13, 18, 21 and X, Y chromosomes. Numerical and structural abnormalities of chromosomes were considered according to the ISCN 2013 system. As a result of the study, 272 (12.1%) cases of genomic and structural abnormalities of the fetus chromosomes of the fetus of pregnant women were registered. Genomic abnormalities were 69.1%, and chromosome structural rearrangements - 30.9%. Among genomic disorders, the frequency of the Down syndrome in the karyotype of the fetus was 58.5%. Frequency of occurrence of fetal chromosomal abnormalities varies significantly depending on the age group of pregnant women. The frequency of fetal chromosomal pathology in pregnant women under 20 years old was 4.4%, at the age from 20 to 34 years old - 7.6%, from 35 to 39 years old - 16.3%, from 40 to 44 years old - 19.8% , after 45 years figure increased significantly - up to 29.6%. In older pregnant women, when compared with pregnant women of the reproductive period from 20 to 34 years, when the highest level of pregnancy rate (54.6%) in the population is observed, there is an increase in the frequency of fetal chromosomal pathology by 2.1; 2.6 and 3.9 times, respectively.