74. NORMAL LIVE BIRTH FROM TWO CARRIERS OF RARE INSERTIONAL TRANSLOCATIONS UNDERGOING PGT

Abstract

Introduction Despite the use of more precise techniques that indicates greater incidence, meiotic segregation of interchromosomal insertion has rarely been studied. Theoretically, the risk to have a child at term with malformation or mental retardation is high but there are no tools to determine this risk. We have investigated the Preimplantation genetic diagnosis (PGT) management of patients with interchromosomal insertion (IT) by fluorescent in situ hybridization (FISH) to obtain a better understanding and improve the genetic counseling. Material & methods Two couples were enrolled in our PGT unit. The male of the first couple carries the IT 46,XY,ins(4;11)(q22;p12p13) and the female karyotype of the second couple is 46,XX,ins(2;10)(q21;q25.2q22). We have investigated, by FISH technique, the meiotic segregation analysis of the sperm of the IT male carrier and embryos providing from the two carriers. One FISH analysis round was performed for the male IT carrier. Five specific probes of chromosomes 4 and 11 were applied to nuclei from spermatozoa and blastomeres from embryo biopsy. An independent X2 test was used to compare abnormal spermatozoa from the patient and the control. Two FISH analysis rounds were performed for the female IT carrier. Six specific probes of chromosomes 2 and 10 were applied to blastomeres of PGT embryos. Result(s) The sperm-FISH segregation analysis showed a significantly increased percentage of unbalanced gametes (52.7%) compared with the control sperm (3.4%, p Conclusion(s) These results permit to reassure the physicians in the management of IT carriers and better guide the genetic counseling. PGT is a suitable diagnostic tool for IT carriers. Sperm FISH analysis contributes to a better IT behavior and segregation understanding. The reanalysis of not transferred whole embryos is essential to avoid misdiagnosis and therefore to contribute to a better IT behavior and segregation understanding. Several studies are needed to specify the risk to ITs carriers and to better assess the risk incurred by the couples.