BACKGROUND: While preimplantation genetic diagnosis (PGD) is well established for carriers of reciprocal terminal translocations, reports on PGD for insertional translocation carriers are lacking. Here, we report on the PGD of an insertional translocation carrier with karyotype 46,XX,ins(14;2)(q21;q31q35). Due to the possibility of crossovers within the inserted region, rather than a single probe, four probes are required for proper embryo selection. METHODS: Probes were generated for PGD using fluorescence in situ hybridization and two PGD cycles. RESULTS: Analysis of 10 embryos revealed four embryos to be normal diploid. Two embryos were consistent with 3:1 segregation of the theoretical quadrivalent and one was consistent with 2:2 or 1:1 segregation. Furthermore, one embryo was mosaic abnormal and one remained without diagnosis. CONCLUSIONS: With increased acceptance of PGD, it is likely that more carriers of complex translocations will enter PGD programmes. The present results suggest that a careful genetic work-up of complex translocations is essential for proper embryo selection. While theoretical modelling may predict that quadrivalents will form during the meiosis of insertional translocations, experimental proof for the occurrence of quadrivalents is still lacking and more research on the meiotic process of both female and male insertional translocation carriers is warranted.
BACKGROUND: While preimplantation genetic diagnosis (PGD) is well established for carriers of reciprocal terminal translocations, reports on PGD for insertional translocation carriers are lacking. Here, we report on the PGD of an insertional translocation carrier with karyotype 46,XX,ins(14;2)(q21;q31q35). Due to the possibility of crossovers within the inserted region, rather than a single probe, four probes are required for proper embryo selection. METHODS: Probes were generated for PGD using fluorescence in situ hybridization and two PGD cycles. RESULTS: Analysis of 10 embryos revealed four embryos to be normal diploid. Two embryos were consistent with 3:1 segregation of the theoretical quadrivalent and one was consistent with 2:2 or 1:1 segregation. Furthermore, one embryo was mosaic abnormal and one remained without diagnosis. CONCLUSIONS: With increased acceptance of PGD, it is likely that more carriers of complex translocations will enter PGD programmes. The present results suggest that a careful genetic work-up of complex translocations is essential for proper embryo selection. While theoretical modelling may predict that quadrivalents will form during the meiosis of insertional translocations, experimental proof for the occurrence of quadrivalents is still lacking and more research on the meiotic process of both female and male insertional translocation carriers is warranted.
Authors: Beata A Nowakowska; Nicole de Leeuw; Claudia Al Ruivenkamp; Birgit Sikkema-Raddatz; John A Crolla; Reinhilde Thoelen; Marije Koopmans; Nicolette den Hollander; Arie van Haeringen; Anne-Marie van der Kevie-Kersemaekers; Rolph Pfundt; Hanneke Mieloo; Ton van Essen; Bert B A de Vries; Andrew Green; Willie Reardon; Jean-Pierre Fryns; Joris R Vermeesch Journal: Eur J Hum Genet Date: 2011-09-14 Impact factor: 4.246
Authors: Cedric Le Caignec; Claudia Spits; Karen Sermon; Martine De Rycke; Bernard Thienpont; Sophie Debrock; Catherine Staessen; Yves Moreau; Jean-Pierre Fryns; Andre Van Steirteghem; Inge Liebaers; Joris R Vermeesch Journal: Nucleic Acids Res Date: 2006-05-12 Impact factor: 16.971