WILL PREIMPLANTATION GENETIC DIAGNOSIS ASSIST PATIENTS WITH A POOR-PROGNOSIS TO ACHIEVE PREGNANCY

PGD (preimplantation genetic diagnosis) of aneuploidy for chromosomes X, Y, 13, 18 and 21 was carried out on 196 embryos from 36 infertile p atients classified with a poor prognosis due to (i) maternal age, (ii) repeated in-vitro fertilization (IVF) failures and (iii) mosaic karyo type, The percentage of abnormal embryos was comparable in the three g roups of patients: maternal age 63%, repeated IVF failure 57%, and mos aic karyotype 62%. The analysis of the overall data revealed an increa sed incidence of abnormal embryos in the older age categories (predomi nantly due to aneuploidy), even in embryos at the 7- to 8-cell stage, In addition, the percentage of chromosomally abnormal embryos was dire ctly proportional to the number of IVF failures, where the increase in chromosomal abnormalities was not correlated to aneuploidy but to oth er aberrations such as mosaicism and polyploidy, Following PGD, 28 pat ients had at least one embryo transferred that appeared normal by fluo rescent in-situ hybridization (FISH), Four clinical pregnancies result ed, with an implantation rate of 10% per normal embryo, In conclusion, the high rate of chromosomally abnormal embryos in poor prognosis pat ients may have been the cause of implantation failure in their previou s IVF cycles, Therefore, the possibility of transferring embryos with a normal FISH complement could improve the chance of pregnancy in this category of patients.