Funding: this work was carried out at the expense of budgetary funds within the framework of research topic № 122032300370-1, “Study of Structural and Functional Features and Mechanisms of the Formation of Chromosomal Abnormalities and Genomic Imbalance.”

Author contribution: Yurchenko DA — study design, development of homemade DNA probes, FISH diagnosis and data interpretation, manuscript writing; Markova ZhG and Minzhenkova ME — FISH analysis with commercial DNA probes; Vorontsova EO — implementation of the protocol of FISH with homemade DNA probes; Shilova NV — study concept and design, discussion, scientific editing of manuscript.

Compliance with ethical standards: the study was approved by the Ethics Committee of the Research Centre for Medical Genetics (protocol No. 4/2 dated 19 April 2021). The patients submitted the informed consent to participation in scientific research.