辅助生殖技术中嵌合胚胎的发生机制及结局

随着胚胎植入前遗传学检测(preimplantation genetic test,PGT)的应用及其诊断方法的不断进步,嵌合胚胎作为整倍体胚胎、非整倍体胚胎以外的第三种胚胎类型,在移植前胚胎中的检出率越来越高。胚胎嵌合可导致流产、死产和遗传异常风险的增加,但也可发育为健康活产儿。嵌合胚胎在染色体异常类型、异常细胞比例和嵌合部位等方面存在很大差异性,为其移植的选择带来了巨大挑战,也使其移植后的结局具有极大未知性。减数分裂形成配子时发生的错误,将导致非整倍体胚胎的形成;而受精卵形成后细胞的有丝分裂错误,产生了嵌合胚胎。理解嵌合胚胎形成机制,了解其检出率及影响因素、发育结局,对避免错误地丢弃具有发育潜力的胚胎至关重要。

Clinical Outcomes of Mosaicism Embryos in Assisted Reproductive Techniques

With the application and improvement of preimplantation genetic test (PGT), the detection rate of mosaic embryos in preimplantation embryos， as the third embryo type other than euploid embryos and aneuploid embryos，is increased. Embryonic mosaicism can increase the risk of miscarriages，stillbirths and genetic abnormalities. However, some mosaic embryos can also result in healthy-live births. Mosaic embryos differ in the types of chromosomal abnormalities, the proportion of abnormal cells and the mosaic sites, which makes great challenge for the choice of transplantation and the uncertainty of clinical outcomes. Meiotic mistakes in gametogenesis lead to aneuploid embryos; mitotic errors during post-zygotic cell division contribute to mosaic embryos. It is very important to understand the mechanism of embryonic mosaicism, incidence, influencing factors and clinical outcomes, for us to avoid falsely discarding embryos with developmental potential.