Genetic Signatures of Chromosome 20 Mosaicism in Recurrent Pregnancy Loss

Abstract

Recurrent pregnancy loss (RPL) causes an immeasurable physical, emotional, and economical impact on the couple. RPL is a complicated challenging scenario in front of gynaecologists working in the area of reprogenomics. Chromosomal aneuploidy and mosaicism are common causes of sporadic early pregnancy loss and play an important proportion in RPL in patients undergoing in vitro fertilization (IVF). In a single-center case series, we report five cases of RPL after implantation of embryos with mosaicism of chromosome 20. The female partners were of advanced maternal age and had a history of previous miscarriages. The couple’s blood karyotype reports were normal and there was no family history of any inherited disease. The chromosomal aneuploidies were screened in day 5 embryos with good morphological grades. The day five trophectoderm biopsies were subjected to Preimplantation genetic screening (PGS) using the next-generation sequencing (NGS) technique. The couples were genetically counseled and written informed consents were taken before implantation explaining all the associated risks. All the clinical parameters were normal and the patients were in close observation with regular follow-up throughout the treatment. These cases had chromosome 20 mosaic embryo transfer resulting in fetal loss in first trimester of pregnancy. Our findings strongly suggest that chromosomal mosaicism in embryos is one of the leading causes of RPL in females with previous miscarriages and advanced maternal age