Assessing the true incidence of mosaicism in preimplantation embryos

• Published in: Fertility and sterility Vol. 107; no. 5; pp. 1107 - 1112
• Main Authors: Vera-Rodriguez, Maria, Ph.D, Rubio, Carmen, Ph.D
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-05-2017
• Subjects: aneuploidy; blastocyst; Chromosome Disorders - embryology; Chromosome Disorders - genetics; Chromosome Disorders - mortality; Chromosome Disorders - prevention & control; embryo; Embryo Implantation - genetics; Embryo Transfer - mortality; Evidence-Based Medicine; Female; Genetic Counseling - methods; Genetic Counseling - statistics & numerical data; Genetic Predisposition to Disease - epidemiology; Genetic Predisposition to Disease - genetics; Genetic Testing - statistics & numerical data; Humans; Incidence; Internal Medicine; Mosaicism; Mosaicism - embryology; Obstetrics and Gynecology; Pregnancy; Pregnancy Outcome; Preimplantation Diagnosis - methods; Preimplantation Diagnosis - statistics & numerical data; preimplantation genetic diagnosis; Reproducibility of Results; Risk Factors; Sensitivity and Specificity; aneuploidy; Mosaicism; blastocyst; embryo; preimplantation genetic diagnosis
• ISSN: 0015-0282; 1556-5653
• DOI: 10.1016/j.fertnstert.2017.03.019

Modern technologies applied to the field of preimplantation genetic diagnosis for aneuploidy screening (PGD-A) have improved the ability to identify the presence of mosaicism. Consequently, new questions can now be addressed regarding the potential impact of embryo mosaicism on diagnosis accuracy and the feasibility of considering mosaic embryos for transfer. The frequency of chromosomal mosaicism in products of conception (POCs) of early miscarriages has been reported to be low. Mosaic embryos with an aneuploid inner cell mass are typically lost during the first trimester owing to spontaneous miscarriages. Most of the mosaics in established pregnancies would derive from placental mosaicism or placental aneuploidy, and mosaic embryos with aneuploid inner cell mass should be lost mainly due to first-trimester spontaneous miscarriages. The well described clinical outcomes of live births from mosaic embryos suggest a wide spectrum of phenotypes, from healthy to severely impaired. Therefore, there is a need to balance the risks of discarding a possibly viable embryo with that of transferring an embryo that may ultimately have a lower implantation potential.