Application of FISH method for preimplantation genetic diagnostics of reciprocal and Robertsonian translocations

Carriers of reciprocal (RCP) and Robertsonian (RT) translocations are known to be at risk for reproductive difficulties. Preimplantation genetic diagnosis (PGD) is one of the options these carriers have to try to fulfill their desire to have a child. The FISH technique is one of the best method to detect RCPs, and, together with the Next Generation Sequencing, to diagnose RTs. The aim of the present study was to assess the usefulness of the FISH method for rapid diagnosis of translocations in our center to improve the reproductive counseling.

From 2008 to 2012 one hundred and twenty seven fresh cycles of the in vitro fertilization (IVF; without freezing embryos) were performed in 42 couples with an RCP and 35 couples with an RT translocations. The patients were diagnosed before IVF as translocation carriers and therefore they opted for PGD. The classical FISH protocol has been applied with specific oligonucleotide probes.

In total 521 blastomeres were tested in order to determine the presence or absence of genetic anomalies resulting from one of the parents being a translocation carrier. Despite the large number of abnormal embryos (407 embryos - 78.1% of all examined embryos), 19.4% of blastomeres appeared to come from a normal or balanced embryos that may have been transferred to the uterus. In 63 of the 127 cycles embryo transfer (ET) was feasible and 24 women had a successful singleton or twin pregnancy. Thus, a live delivery rate of 18.9% per started cycles and 38.1% per cycle with ET was obtained.

FISH should be regarded as an optimal preimplantation genetic diagnosis method for specific RCP and RT translocation carriers to increase the chance of successful IVF procedure.