Assessment of numeric abnormalities of X, Y, 18, and 16 chromosomes in preimplantation XXXX embryos before transfer.

@entity1 @entity2007 @entity5700
OBJECTIVE: Our purpose was to determine the feasibility of ascertaining @entity2007 for chromosomes X, Y, 18, and 16 by use of multiple-probe fluorescence in situ hybridization in blastomeres from preimplantation @entity1 embryos. STUDY DESIGN: A short fluorescence in situ hybridization procedure involving the simultaneous use of four deoxyribonucleic acid probes detected with red, green, blue, or a mixture of red and green fluorochromes was developed to determine numeric abnormalities of chromosomes X, Y, 18, and 16. Embryos underwent biopsy, and all or most cells were analyzed to distinguish true @entity2007 from mosaicism and to assess technique variations within the same embryo (n = 64). RESULTS: The analysis of all the blastomeres of an embryo was achieved in 91% of the embryos. Successful analyses including biopsy, fixation, and fluorescence in situ hybridization were achieved in 87.8% of the blastomeres. Of the four chromosomes tested, numeric aberrations were found in 23% and 42% of normally and abnormally developing embryos, respectively, including @entity2007 , @entity5700 , haploidy, and mosaicism. When diploid embryos containing one or several tetraploid cells are counted as chromosomally abnormal, then 49% and 61% of normally and abnormally developing embryos, respectively, were chromosomally abnormal. @entity2007 consisted of two monosomies for chromosome 16, one for chromosome 18, and a trisomy for chromosome 16. There was a tendency for @entity2007 to increase with maternal age. CONCLUSIONS: Fluorescence in situ hybridization is a more efficient method than cytogenetic analysis to study specific aneuploidies at preimplantation stages of development in @entity1 embryos. In addition, the preimplantation genetic diagnosis of two blastomeres per eight-cell embryo may be sufficient to ensure successful analysis of @entity5700 , haploidy, and specific aneuploidies without endangering the survival of the embryo. The technique can be easily modified to consider other chromosomes, including 13 and 21. Because most chromosomally abnormal embryos do not develop to term, the use of this technique may increase the delivery rate per embryo by allowing only transfer of embryos normal for the tested chromosomes. This technique would be most useful for older @entity1 undergoing in vitro fertilization, because @entity2007 appears to increase with advancing maternal age.
