| Objective:To determine the feasibility of ascertaining aneuploidy for chromosomes 18, X and Y using of fluorescence in situ hybridization (FISH) in blastomeres from embryos, and analyze the ralative factors of chromosomal abnormalities. Develope an accurate and rapid PGD technique fit for our IVF centre.Methods:We choosed 72 abnormal developping embryos of 34 couples from 2010.8 to 2011.2 and thawed 40 cryopreserved embryos of 12 couples from 2007.6 to 2009.12 and analyzed all blastomeres after biopsy. The patients were informed consent for FISH analysis on their abanded embryos. All samples were divided into different groups by fertilization, woman age, protocol of COH, dosage of Gn, days of Gn. Embryos were biopsied by using Tyrode acid fluid, then fix blastomeres by using HCL/Tween-20+Methanol/glacial acetic acidmethod. Then a short FISH procedure was developed to all of the nucleus determine numeric abnormalities chromosomes involving the simultaneous use of chromose-specific deoxyribonucleic acid probes of 18, X and Y chromosomes marked with blue, green, red, respectively. Choose 20 amniotic fluid cells samples of DS high risk in serologic screening from 2010.6 to 2010.12 as control. FISH results were compared to the karyotype analysis.Results:91.96% of embryos were biopsied,86.48% of blastomeres were fixed and 89.82% were hybridazated successfully. Of the 3 chromosomes tested, numeric aberrations can be found including polyploidy, haploidy and mosaicism. No significant difference between abnormal developing embryos and good quality cryopreserved embryos were found in chromosome aberration rates(43.33% vs 35.90%, P>0.05) and mosaicism rates (21.66% vs 28.21%, P>0.05). Also, no significant difference between IVF group and ICSI group were found in chromosome aberration rates(38.71% vs 43.24%, P>0.05) and mosaicism rates (17.74% vs 27.03%, P>0.05). The chromosome aberration rates had no significant difference in older women than younger women (55.17% vs 34.28%, P>0.05), but the mosaicism rates was significantly higher in older women than in younger women (41.38% vs 17.14%, P<0.05). There were no significant difference between short GnRH-a propocol group and long GnRH-a propocol group in the chromosome aberration rates(36.17% vs 44.23%, P>0.05) and mosaicism rates (21.28% vs 26.92%, P>0.05). The chromosome aberration rates was significantly higher in group of Gn dosage≥24 than in group of Gn dosage<24 (53.33% vs 35.29%, P<0.05), but the mosaicism rates had no significant difference in the two groups (31.11%vs 18.52%, P>0.05). There were no significant difference between group of Gn days≥9 and group of Gn days<9 in the chromosome aberration rates(43.86%vs 35.71%, P>0.05) and mosaicism rates (21.05% vs 28.57%, P>0.05).Conclusion:FISH is an efficient method to study specific aneuploidies at preimplantation stages of human embryos. FISH is specific, exact, easy to judge, and rapid to achieve results not to affect the embryos transfer. There are not significant difference between good quality embryos cryopreserved and abnormal developing embryos. So slow cooling and/or thawing procedure maybe increase chromosome aberration, but more samples should be demonstrated. A part of normal fertilization embryos is of chromosomal abnormality, and quite a number of them are mosaicism. These embryos of Chromosome abnormalities may lead to low implantation rates and high abortion rate after transplantation. Aneuploidy appears to increase in older women (≥35 years) undergoing in vitro fertilization or larger dosage of Gn. So older women are suggested to detect aneuploidy using FISH to screen normal embryos to increase pregnancy rate and live birth rate and reduce abortion rate.
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