P-561 Clinical outcomes following PGT-M and PGT-SR cycles
Authors: Hayat S , Hemingway V , Heath C , Cawood S , Kasaven L , Alchami A , Ozturk O , Seshadri S , Serhal P , Odia R , Ben Nagi J 
Published: July 2024

Abstract

Study question
Are the clinical outcomes following PGT-M Superior to PGT-SR and do female carriers of SR have more favourable outcomes than male carriers?

Summary answer
PGT-SR group was associated with improved clinical outcomes compared to PGT-M group. A higher PR and LBR observed amongst PGT-SR female carriers compared to males.

What is known already
Pre-implantation genetic testing for monogenic disorders (PGT-M) involves the genetic screening of embryos prior to transfer, where two individuals are carriers or affected by a specific genetic condition. Pre-implantation genetic testing for structural rearrangement (PGT-SR), however, tests for embryos in individuals who are carriers of Robertsonian or reciprocal translocations. The aim of both screening tests is to avoid passing on a known genetic condition to an offspring, resulting in fatal outcomes including physical or mental disabilities. Some studies have demonstrated improved clinical outcomes following PGT-M compared to PGT-SR. However, there is limited understanding of why this may be the case.

Study design, size, duration
Retrospective study of 916 patients who underwent PGD (M/SR) cycles carried out between 2015 to 2022 at a single fertility centre. There were (n = 759) who underwent PGT-M and (n = 157) PGT-SR. Clinical outcomes: pregnancy (PR), clinical pregnancy (CPR) and live birth (LBR) were determined following transfer of either an unaffected/euploid, or carrier/euploid embryo after PGT-M and transfer of a balanced/euploid embryo following PGT-SR. Subgroup analysis compared cycles including PGT-SR female carriers (n = 55) with male carriers (n = 102).

Participants/materials, setting, methods
Data was collected from the medical database (IDEAS). The overall mean age at oocyte retrieval was 32.9 (SD 3.7) years. SPSS software was used to determine whether PR, CPR and LBR were statistically significant when the two groups were compared. student t-test where (p &lt; 0.05) is statistically significant was applied.

Main results and the role of chance
Clinical outcomes for PGT-M vs PGT-SR were comparable and not statistically significant: PR (66% vs 69%; p = 0.310) CPR (60% vs 61%; p = 0.930), LBR (55% vs 59%; p = 0.359) respectively. PR (80% vs 63%; p = 0.02), CPR (69% vs 56%; p = 0.10) and LBR (69% vs 54%; p = 0.06) were superior following PGT-SR amongst female carriers (n = 44/55), compared to male carriers (n = 64/102) respectively. However, only the pregnancy rate was statistically significant when the female was the carrier. Quality of the blastocyst(s) transferred was also higher amongst PGT-SR cycles where the female was the carrier.

Limitations, reasons for caution
The sample size of the PGT-SR group for both male and female carriers were significantly lower compared to the PGT-M group. A larger and equal sample size is required in order to generalise findings.

Wider implications of the findings
The quality of the blastocyst transferred has a significant effect on clinical outcomes, despite the euploid status. Such findings can be used to counsel patients or couples who consider undergoing IVF for the purpose of PGT-M/SR genetic screening prior to embryo transfer.

Trial registration number
IRB-0001CRGH-CITY-FL-2024