## IVFโ Screening Test May โคNotโฃ Captureโค All Genetic โคIssues, New Research Suggests
A commonly used preimplantation genetic testing โfor โขaneuploidy (PGT-A) procedure may notโ detect all genetic abnormalities that develop in embryos, according to recent findings. The test, performed โapproximately 5 to 6 days afterโข fertilization, analyzes cellsโฃ from the embryo’s outerโ layer for extra or missing chromosomes – factors that โcan increase miscarriage risk. Though, researchers have discoveredโฃ that โgenetic changes canโฃ occur *after* this testing window, possibly leadingโค to inaccurate โassessments of โembryo viability.
Researchers at the University of cambridge, โled โby Ahmed Abdelbaki, utilized a light-sheetโ microscope โtoโฃ observe the development โฃof human embryos for 46 hours following thawing, mirroring the timeframe between โคPGT-A and implantation. This extended observationโค period was made possible byโ the light-sheet โmicroscope’s โฃreduced light โคexposure โcomparedโข to conventional methods,which can damage sensitive embryos. Previous studies were limited to approximately 24 โhours of imaging.Theโ team injected a fluorescent dye into 13โ human embryos to track genetic changes in real-time. Across 223โ observed cellโฃ divisions,โ theyโค found that โค8 percent of โฃcellsโ experienced chromosome misalignment โ- a critical event where chromosomes fail to properly align before โdividing. This misalignment considerablyโ increases โขtheโข risk โof cells with an incorrect number of chromosomes, potentially hindering implantation, raising โคmiscarriage risk, or leading to conditionsโฃ likeโ Down syndrome.
Lilli Zimmerman โคof Northwell Health in New York state, explains that the โคfindingsโข suggest “there may be later [genetic] changes inโ the โembryo after โคthe point at which we โขare screening with โฃPGT-A.”
Importantly, the observed errors were limited to the cells of the outer layer, which ultimatelyโ form the placenta, and not the inner cells that โฃdevelopโ into the fetus. previousโ research has indicated that embryos with some genetic abnormalities in placental cells can still โresult in accomplishedโ pregnancies. Thus, Abdelbaki suggests these newly observed genetic errors may not necessarily impact embryo viability.Zimmerman emphasizes โฃthe need for further research into embryo screening, stating, “What thisโค study, to me, really โshows is that there is still a lot more research needed in terms of screening embryos for whether [they] โคareโค genetically normal or abnormal.” She also notes the study’s limitedโฃ sample โขsize – only 13 embryos were observed – making it difficult to generalize the โฃresults broadly.The impact of these post-screening genetic โerrors on embryo viability remains unclear.
