70. PREIMPLANTATION GENETIC TESTING FOR YQH-AUTOSOME TRANSLOCATION CARRIERS: ANALYSIS OF GAMETE SEGREGATION

Introduction Y-autosome translocations occur in approximately 1:2000 in population and represent special group of reciprocal exchanges. Due to a balanced nature they do not influence on phenotype in general. However, Y-autosome translocation can dislocate sex bivalent formation and chromosome synapsis in the first meiotic division prophase that led to gamete aneuploidy or pachytene arrest. More often Y-derived DNA, predominantly Yq12 band, is translocated onto the short arm of acrocentric chromosomes, mainly chromosomes 15 and 22 due to a strong correlation in their satellite DNA sequences. In women inheritance of such derivative acrocentric chromosomes could be associated with the risk of ovarian malignancy, but the particular mechanism of this pathological effect is not entirely clear since the Yq12 band consists of tandemly organized satellite DNA sequences. It can be associated with the transcription of satellite DNAwhich occurs during carcinogenesis. Material & methods Two families with Yq12/15p and one – with Yq12/22p translocations were analyzed during IVF cycle with PGT in International Centre for Reproductive Medicine. The mean age of men and women was 36±2.8 and 34.25±1.4 years respectively. Karyotyping analysis was performed using GTG banding technique on metaphase chromosomes from peripheral blood lymphocytes. Fluorescence in situ hybridization (FISH) was used to clarify the breakpoint on chromosomes and confirm the chromosomes-specificity of the probes. Additionally, seven chromosomes (13, 14, 15 or 22, 16, 18, 21, X), which are not involved in rearrangement, were analyzed. Results FISH with chromosome specific probes was performed on blastomere from cleavage-stage embryo. A total of 42 blastomeres were analyzed. In 43% of the blastomeres «adjacent-1» segregationwith derivate autosome and X or Y chromosomes was revealed. Segregation 3:1 was observed in 10% of the cells, with no predominant inheritance of the derivative autosome. In 21% of cells the type of chromosome segregation could not be determined due to mosaicismor polyploidy. 45% of the cells were aneuploid for autosomes, which are not involved in the translocation, which may be connected with interchromosomal effect. Conclusions Carriers of Yq12/15p or Yq12/22p translocations have a predominant inheritance of the derivative autosome, which can be associated with the disruption ofsex bivalent segregation. This research was supported by Russian Foundation for Basic Research (grant # 18-34-00279 ).