Backgraund. In order to analyze the diversity of somatic mutations in the MED12 gene in the myomatous nodes of patients with multiple fibroids, to compare the occurrence of various types of such mutations in multiple nodes with data on the frequency of mutations in fibroids in general and the results of studies on the detection of such mutations in the myometrium. Materials and methods. samples of 62 patients with multiple uterine fibroids (from 2 to 14 operatively removed myomatous nodes, 264 nodes in total) were studied. After DNA isolation, PCR and amplicon sequencing, the obtained nucleotide sequences were analyzed for the presence of single nucleotide substitutions, as well as deletions and insertions of nucleotides in exon 2 of the MED12 gene. Results. The total frequency of detected somatic mutations in the MED12 gene in the studied sample was 56%. The obtained mutation rates in multiple nodes were compared with data on large samples of fibroids and data on the presence of such mutations in intact myometrial cells. The correspondence of the frequencies of different mutation variants was revealed. The data obtained on the distribution of somatic mutations in exon 2 of the MED12 gene in multiple uterine fibroids indicate frequent spontaneous mutagenesis in myometrial cells and a high probability of developing myomatous nodules with various mutations in multiple fibroids. The distribution of mutation frequencies in the MED12 gene of different types in the nodes of multiple fibroids practically does not differ from the distribution in the general samples obtained both in our work and taken from published data. The data on the detection of such mutations in the myometrium also generally repeat the distribution by type of mutations, which allows us to conclude that deletions occur with the same frequency in myometrial cells. Conclusions. Mutations in the MED12 gene are the most common trigger that causes myometrial cell degeneration. In the Russian population, the prevalence of such mutations in uterine leiomyoma nodules is 50—60%, while with multiple fibroids, patients have nodes with various mutations (both single-nucleotide and deletions), along with nodes that do not have such mutations.
Kuznetsova et al. (Fri,) studied this question.