Subtle translocation does not affect euploid blastocyst rate or pregnancy outcomes during preimplantation genetic testing.

Research question: Do chromosomal translocation segment size and proportion affect embryo euploidy and pregnancy outcomes during preimplantation genetic testing (PGT) cycles in subtle translocation carriers?

Design: Retrospective cohort study including 207 couples with reciprocal translocation who underwent 232 PGT for structural rearrangements cycles; euploid blastocysts were selected for transfer. A total of 119 couples completed 155 warming transfer cycles, and 58 cycles resulted in clinical pregnancy. According to the size of the translocation segment (threshold 10 Mb), couples were divided into subtle translocation group 1 (translocation segment on either chromosome was <10 Mb) and control group 1 (translocation segments on both chromosomes were ≥10 Mb). Couples were divided into subtle translocation group 2 (proportion on either chromosome segment was <5% relative to the whole chromosome) and control group 2 (proportions on both chromosome segments were ≥5% relative to the whole chromosome). Rates of euploid blastocysts and clinical outcomes were analysed.

Results: No significant differences were found in the rates of euploid blastocysts, (37.11% versus 36.08%; P = 0.817) and clinical pregnancy (32.56% versus 39.28%; P = 0.438) compared with subtle translocation group 1 and control group 1, respectively. Similarly, no significant differences were found in the rates of euploid blastocysts (35.00% versus 36.75%; P = 0.572) and clinical pregnancy (34.28% versus 38.33%; P = 0.663) compared with subtle translocation group 2 and control group 2.

Conclusions: The size and proportion of a translocation segment did not significantly affect the rate of euploid blastocysts or pregnancy outcomes during PGT cycles for couples with chromosomal translocations.