Number of embryos biopsied as a predictive indicator for the outcome of preimplantation genetic diagnosis by fluorescence in situ hybridisation in translocation cases.

This study aimed to investigate the optimum number of embryos to be biopsied in order to increase the likelihood of obtaining a balanced/normal embryo following preimplantation genetic diagnosis (PGD) by fluorescence in situ hybridisation (FISH) for translocation carriers. Patients with low number of fertilised oocytes (≤5) or low number of embryos available for PGD (<7) underwent multiple hormonal stimulation cycles and their embryos from each cycle were vitrified and accumulated to obtain at least three embryos for PGD. Fifty-seven PGD cycles were performed for translocation carriers by FISH on day 3 of embryo development. PGD and pregnancy outcomes were examined according to the number of embryos biopsied. The cancellation rates of embryo transfer for the reciprocal translocation carriers were 40% when more than eight embryos were biopsied and it was as high as 78% when low number of embryos (less than nine) were biopsied. For Robertsonian translocation carriers, when more than eight embryos were biopsied, there were no embryo transfer cancellations. This study showed that when there are more than nine embryos biopsied for PGD, the likelihood of obtaining a balanced embryo and positive pregnancy outcome is significantly higher (P < 0.05) in such the overall pregnancy rate was 63% for reciprocal and 86% for Robertsonian carriers. This was reduced to only 7% for reciprocal and 14% for Robertsonian translocation carriers when less than nine embryos were biopsied. One of the limitations of this study was that the analysis was performed by FISH and more studies should investigate the outcomes of embryo accumulation following comprehensive chromosome analysis.

Poor embryo development and preimplantation genetic diagnosis outcomes of translocations involving chromosome 10: Do we blame genetics?

Balanced reciprocal translocation carriers are usually phenotypically normal. Although the reproductive risk of these carriers varies, they generally have a lower chance to produce normal or balanced gametes. Preimplantation genetic diagnosis (PGD) is offered to these patients to increase their chances of becoming pregnant by selecting a balanced embryo for transfer. This study aimed to analyse the development and the PGD outcome of the embryos obtained from reciprocal translocation carriers focusing on ones with chromosome 10 rearrangements. In total, 27 reciprocal translocation carriers underwent 31 cycles of PGD. PGD was performed using multicolour fluorescence in situ hybridisation for 298 embryos and of these 136 were obtained from couples carrying translocations involving chromosome 10 rearrangements. Carriers of translocations involving chromosome 10 rearrangements have a lower chance of producing normal or balanced embryos compared with the carriers with other rearrangements. The development of embryos obtained from the patients with chromosome 10 rearrangements was impaired and only a limited number of embryos developed to the blastocyst stage.

Successful preimplantation genetic aneuploidy screening in Turkish patients.

Preimplantation genetic diagnosis is a preventive approach for identifying genetic abnormalities in early stages of reproduction. We used preimplantation genetic aneuploidy screening in 230 cycles of patients with indications of advanced maternal age, recurrent implantation failure, recurrent spontaneous abortions, or severe male factor. Biopsied blastomeres from embryos with six to eight blastomeres on day 3 were fixed and fluorescence in situ hybridization was utilized on chromosomes 13, 16, 18, 21, 22, X, and Y. Among 945 morphologically normal embryos, 314 were diagnosed as chromosomally normal. Trisomy and monosomy were observed in 36% of the cases (18% each). Embryo transfer was used in 144 cycles, resulting in 41 pregnancies. Thirty-seven healthy babies were delivered, with a take-home baby rate of 24.2% and an implantation rate of 22%. We recommend preimplantation genetic aneuploidy screening as a valuable technique to select normal chromosome embryos in order to avoid multiple pregnancies due to the multiple embryo transfers that are normally necessary to ensure pregnancy in poor prognosis in vitro fertilization patients.

Cytogenetic results of amniocentesis materials: incidence of abnormal karyotypes in the Turkish collaborative study.

The experience on prenatal chromosome diagnosis of four Turkish centers participating in a collaborative study on 6041 genetic amniocentesis performed during a 4-8 years period were reviewed. 5887 (97.5%) patients had strong clinical indications for prenatal chromosome studies and 154 (2.5%) were referred because of maternal anxiety and a bad history of previous gestations. The main indication groups were: advanced maternal age (3197 cases), positive serum screening (2011 cases), ultrasound-identified anomaly (492 cases), previous fetus/child with chromosomal aberrations (103 cases), a history of a previous abnormal and/or mentally handicapped child (70 cases) and a parental chromosome rearrangement (14 cases). The average maternal age was 33.9 years and average gestational age was 18 weeks. A total of 179 affected fetuses were detected in this collaborative study (3%) of which 133 were unbalanced (74.3%). Among the 124 (69%) numerical aberrations, 102 (82.3%) were autosomal aneuploidies, 20 (16.1%) were gonosomal aneuploidies and 2 (1.6%) were poliploidies. Among the 55 (31%) structural aberrations, balanced translocation was the most common (63.6%) and 11 cases of inversion, four cases of unbalanced translocation, two cases of marker chromosome and three cases of other abnormalities were found. The overall culture success rate was 99.7%. Pregnancy termination that is permitted by legal authorities was accepted by 94.7% (126/133) with parents at unbalanced cytogenetic result announcement.