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Objectives: According to French recommendations, only the caryotype is carried out as a first line in candidates for gamete donation. The prescription of additional genetic tests for variants responsible for serious monogenic diseases is only recommended in the case of call points. However, cystic fibrosis remains the most common genetic disease with serious consequences in childhood. The purpose is to assess the different screening strategies in the Centres d'Études et de Conservation des Œufs et du Sperme humain (CECOS) regarding abnormalities of the Cystic Fibrosis Transmembrane conductance Regulator gene (CFTR)., Method: Our study is based on the analysis of data collected using a questionnaire. Private centres authorised to donate have been excluded from this work., Results: Twenty-six centres participated out of the 33 interviewees. Two centres carry out systematic screening in all their sperm donation candidates while only one centre practises it in its oocyte donation candidates. For the other 23 centres, research is carried out in case of strong clinical suspicions according to personal or family history and when one of the two members of the recipient couple has a known variant. Regarding the molecular analysis technique used, 56.5% of centres use PCR with commercial kits, whereas the other centers use next-generation sequencing., Conclusion: Targeted screening therefore remains widely practiced in France unlike other countries. Moving to expanded systematic screening raises ethical, financial and organisational issues., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Objective: Blastocyst biopsy has recently been implemented in our laboratory for PGT with a "freeze all" indication. The aim of this study is to compare PGT results between embryos biopsied at the cleaved and embryos biopsied at the blastocyst stage., Study Design: This is a retrospective cohort study conducted from January 2017 to December 2022 in France. All couples with a "freeze all" indication the day of hCG trigerring during the study period were included in the study. Patients were retrospectively assigned in one group of two groups based on the day of embryo biopsy: the cleavage group if a blastomere biopsy was performed on day 3/4 or the blastocyst group if a trophectoderm biopsy was performed on day 5/6. We evaluated and compared the results between the two groups for biological parameters and clinical outcomes., Results: In total, 325 PGT cycles (291 patients) were included in our study. Frozen-thawed embryo transfer was performed for 285 cycles, 122 in the blastocyst group and 163 in the cleavage group. The number of biopsied embryos per cycle is significantly higher in the cleavage group with a mean of 7.2 ± 4.1 embryos biopsied per cycle vs. 2.9 ± 2.8 embryos in the blastocyst group (p < 0.001). The rate of the useful embryos was similar between the two groups with 14.6 % of frozen healthy embryos among the 1352 cleaved embryos obtained in blastocyst group, compared to 17.1 % in the cleavage group. No significant differences in clinical pregnancy rate per transfer and implantation rate were observed between the blastocyst and cleavage groups (36.4% vs. 40.4 % and 33.1% vs. 33.2 % respectively)., Conclusions: For "freeze all" PGT cycles, the day of embryo biopsy (cleaved vs blastocyst biopsy) does not impact pregnancy outcomes. Knowing how to perform embryo biopsy at different stages helps to better organize daily laboratory activity and to rescue some undiagnosed embryos after day 3 biopsy., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023. Published by Elsevier Masson SAS.)