植入前胚胎染色体嵌合型的初步分析

目的　应用荧光原位杂交 (FISH)技术对人类早期胚胎染色体的嵌合型进行初步分析 ,并探讨胚胎染色体嵌合型对常规体外受精 胚胎移植 (IVF ET)成功率以及植入前诊断的影响。方法　对IVF ET治疗周期中胚胎质量差、不适于胚胎移植和冷冻保存的正常受精胚胎以及在植入前胚胎性别诊断中诊断为男性胚胎、不能移植的 38个胚胎进行FISH。结果　 38个胚胎共有 2 93个核 ,杂交率为 96 .2 %。其中正常胚胎 12个 ,占 31.6 % ,二倍体胚胎 (正常胚胎 二倍体嵌合型胚胎 ) 2 8个 ,占73.7% ,嵌合型胚胎 (二倍体嵌合型胚胎 异常嵌合型胚胎 ) 19个 ,占 5 0 .0 %。在≤ 4细胞期胚胎中 ,嵌合型胚胎占 18.2 % ,但在 5～ 8细胞期和≥ 9细胞期胚胎中 ,嵌合型胚胎的比例分别增至 6 8.4%和5 0 .0 %。结论　随着卵裂次数的增加 ,嵌合型胚胎所占的比例也增加 ,但嵌合型胚胎中嵌合细胞的比例却随之而降低。胚胎染色体的嵌合型可能是影响常规IVF ET成功率的重要因素。应用FISH技术可准确地进行单细胞植入前性别诊断 ,但在进行植入前单基因诊断时 ,最好能同时活检 2个细胞 ,以增加准确度。

Preliminary Analysis of Chromosome Mosaicism in Preimplantation Embryos

OBJECTIVE: Using fluorescence in situ hybridization to analyze chromosome mosaicism in human preimplantation embryos and access the influence of mosaicism on in vitro fertilization-embryo transfer (IVF-ET) and preimplantation genetic diagnosis. METHODS: Normal fertilized embryos, which were not suitable for embryo transfer and cryopreservation, and male embryos in preimplantation gender diagnosis were analyzed by fluorescence in situ hybridization. RESULTS: Two hundred and ninety three nucleuses were found among 38 embryos. The hybridization rate was 96.2%. Twelve embryos (31.6%) were normal. Twenty-eight embryos (73.7%) were diploid embryos, which included normal diploid embryos and embryos with diploid moscaicism. In addition, 19 (50.0%) embryos were considered to be chromosomal mosaics due to diploid mosaicism and abnormal mosaicsm. The frequency of mosaicism increased from 18.2% in < or = 4 cell-stage embryos to 68.4% and 50.0% in 5-8 cell-stage and > or = 9 cell-stage embryos respectively. CONCLUSION: The frequency of Mosaicism increases with successive cleavage divisions. Moscaicism may be one of the important factors affecting the success rates in IVF-ET. Identification of sex by analysis of a single cleavage cell is accurate; however, it would be better to biopsy 2 cells to reduce errors in preimplantation genetic diagnosis of single gene diseases.