PGD是否異常無法全然代表未來胚胎是否正常‧

PGD目前最被質疑之處為相當高比例本身同時具有正常與不正常之胚葉細胞(mosaicism ，10-90%不正常之胚葉細胞)
57%之Day 3胚胎 & 45%之Day 5胚胎具mosaicism現象

由於胚胎具自我修復異常細胞現象，PGD所檢驗胚葉細胞是否異常無法全然代表未來胚胎是否正常‧

http://humrep.oxfordjournals.org/content/21/1/223.full

Preimplantation genetic screening reveals a high incidence of aneuploidy and mosaicism in embryos from young women undergoing IVF

1. E.B. Baart ¹ , ⁴ , 
2. E. Martini ¹ , 
3. I. van den Berg ¹ , ² , 
4. N.S. Macklon ¹ , ³ ,
5. R-J.H. Galjaard ² , 
6. B.C.J.M. Fauser ¹ , ³ and 
7. D. Van Opstal ²

+Author Affiliations

1. ¹Division of Reproductive Medicine, Department of Obstetrics and Gynaecology and ²Department of Clinical Genetics, Erasmus MC, University Medical Center, Dr. Molewaterplein 40, 3015 GD Rotterdam and ³Department of Reproductive Medicine, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands

1. 4To whom correspondence should be addressed. E-mail: e.baart@erasmusmc.nl

 

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Abstract

BACKGROUND: In order to assess the frequency of aneuploidy and mosaicism in embryos obtained from IVF patients aged <38 years, preimplantation genetic screening (PGS) was performed after biopsy of two blastomeres. Furthermore, the reliability of this diagnosis was assessed by performing reanalysis of the embryo on day 5. METHOD: The copy numbers of 10 chromosomes (1, 7, 13, 15, 16, 18, 21, 22, X and Y) were investigated by fluorescence in situ hybridization (FISH) analysis. Embryos that were found to be abnormal or of insufficient morphological quality were cultured until day 5 and reanalysed. Results obtained were compared to the day 3 blastomere analysis. RESULTS: After analysis of 196 embryos (one cell in 38% and two cells in 62%), only 36% of the embryos were found to be normal on day 3. After analysis of two blastomeres, 50% showed chromosomal mosaicism. Comparison of the FISH results from day 3 blastomeres and day 5 embryos yielded an overall cytogenetic confirmation rate of 54%. CONCLUSIONS: The rates of mosaicism and aneuploidy in these embryos from young IVF patients are similar to those published for older women. We found the best confirmation rate after a diagnosis based on two cells, where both blastomeres showed the same chromosomal abnormality. In contrast, after a mosaic diagnosis the confirmation rate was low. The present study provides the first detailed reanalysis data of embryos analysed by PGS and clearly demonstrates the impact of mosaicism on the reliability of the PGS diagnosis.