P-736 Balanced cryptic chromosomal rearrangement carriers detection by optical genome mapping (OGM)

Abstract Study question To evaluate diagnosis value of optical genome mapping (OGM) for potential preimplantation genetic testing in chromosomal structural rearrangement (PGT-SR) patients with cryptic rearrangement. Summary answer OGM is an efficient method detection. However, SVs near telomere and centromere regions could hardly be reported this method. What known already About 5∼10% infertility or sterility people carry balanced variations (SVs) high risks miscarriage birth defects resulting from imbalanced gametes when producing fetus. some specific location small fragments cannot detected by traditional cytogenetic techniques like G-banding CNV-seq. Currently, several optimized are able to detect typically abnormality. OGM, the molecular detection technique relying on new principle recent years, have overcome shortcomings former potentially capable both routine well. design, size, duration From 2019 2022, 12 couples The First Affiliated Hospital Sun Yat-sen University People’s Yunnan Province history offspring defect, recurrent unexplained unexpected copy number variation embryos previous PGT cycles were included re-analysis. Participants/materials, setting, methods Peripheral blood lymphocytes these collected karyotype analysis(G-400 banding), FISH, CNV-seq, third generation sequencing(Nanopore). results test compared accuracy structure vatiation. Main role chance In 11 bearing adverse pregnancy childbirth defect normal G-banding, discovered novel chromosome translocations inversion 9 (81.81%). 1 couple t(4:17)(q12;p13) diagnosed additional translocation t(17;19)(q12;p13), which produced repeated CNVs chromosome19 observed two cycles. For fragment translocation, terminal inversion, abnormal 500kbs. confirmed FISH sequencing (Nanopore) embryo mutation. breaking position Nanopore comparable. sum, further information 83.33% (10/12) duplication depletion abortus. Limitations, reasons caution Due limitation principle, abnormalities special locations (centromere, secondary constriction, etc.) detected. has sensitivity many mutations, requires examiners strong ability analyze counseling. price also limits promotion application. Wider implications findings can provide more precious result SVs, PGT-SR definitely improve outcome certain population rearrangements. shortcoming not been overcame yet, so it suggested as auxiliary beside conventional G-binding circumstances ART population. Trial registration Not applicable