Application of the FISH Method for Analyzing Chromosome Segregation Patterns in Preimplantation Embryos from Robertsonian Translocation Carriers

Abstract

Robertsonian translocations (RTs) are very common balanced structural chromosome rearrangements in humans. Due to alterations in the chromosome segregation pattern and the formation of unbalanced gametes and embryos, the carriers of RTs have a significant risk of reproductive failure. For over 30 years, fluorescent in situ hybridization (FISH) has been used for preimplantation genetic testing for chromosomal structural rearrangement (PGT-SR) in carriers of RTs. The data obtained by performing FISH for PGT-SR can be useful for analyzing segregation patterns in preimplantation embryos. We analyzed chromosome segregation patterns in 964 embryos from 100 couples who were carriers of various types of RTs by performing FISH or using the array comparative genomic hybridization (aCGH) method. When the carriers were male, the predominant segregation mode was alternate (detected in 42.4% of embryos), whereas, when the carriers were female, alternate and adjacent types of segregation were detected in most embryos (32.3% and 26.6% of embryos, respectively). About 33% of balanced/euploid embryos in IVF cycles were formed when the carriers of RT were male, and about 24% of such embryos were formed when the carriers were female. No association was found between sperm parameters and malsegregation rates in male carriers of RT. In this study, we found that female and male RT carriers have different reproductive risks associated with chromosome segregation patterns and the rate of balanced/euploid embryos.