title: Variable aneuploidy mechanisms in embryos from couples with poor reproductive histories undergoing preimplantation genetic screening.
abstract: BACKGROUND
  Preimplantation genetic screening (PGS) is used to determine the chromosome status of human embryos from patients with advanced maternal age (AMA), recurrent miscarriage (RM) or repeated implantation failure (RIF).
  
  
  METHODS
  Embryos from 47 such couples were investigated for chromosomes 13, 15, 16, 18, 21 and 22 using fluorescence in situ hybridization with two rounds of hybridization. The investigation included parental lymphocyte work-up, the screening of blastomeres on day 3 and full follow-up on day 5/6 of untransferred embryos.
  
  
  RESULTS
  The outcome of 60 PGS cycles is described, in which 523 embryos were biopsied; 91% gave results, of which 18% were diploid for all the chromosomes tested and 82% were abnormal. The pregnancy rate per cycle that reached the biopsy stage was 27%, and 30% per embryo transfer. Satisfactory follow-up was obtained from 353 embryos; all those diagnosed as abnormal were confirmed as such, although two false-positives were detected in relation to specific chromosome abnormalities. Meiotic errors were identified in 16% of embryos. Between the RM, AMA and RIF groups, there was a significant difference in the distribution of embryos that were uniformly abnormal and of those with meiotic errors; with an almost 3-fold increase in meiotic errors in the first two groups compared with the RIF group.
  
  
  CONCLUSIONS
  This complete investigation has identified significant differences between referral groups concerning the origin of aneuploidy in their embryos.
authors.affiliation: Department of Obstetrics and Gynaecology, University College London Centre for Preimplantation Genetic Diagnosis, and The Assisted Conception Unit, University College London Hospitals Foundation Trust, UK. a.mantzouratou@ucl.ac.uk
authors.forename: A
authors.initials: A
authors.lastname: Mantzouratou
authors.forename: A
authors.initials: A
authors.lastname: Mania
authors.forename: E
authors.initials: E
authors.lastname: Fragouli
authors.forename: L
authors.initials: L
authors.lastname: Xanthopoulou
authors.forename: S
authors.initials: S
authors.lastname: Tashkandi
authors.forename: K
authors.initials: K
authors.lastname: Fordham
authors.forename: D M
authors.initials: DM
authors.lastname: Ranieri
authors.forename: A
authors.initials: A
authors.lastname: Doshi
authors.forename: S
authors.initials: S
authors.lastname: Nuttall
authors.forename: J C
authors.initials: JC
authors.lastname: Harper
authors.forename: P
authors.initials: P
authors.lastname: Serhal
authors.forename: J D A
authors.initials: JD
authors.lastname: Delhanty
mesh_terms: D000026:Abortion, Habitual; D000328:Adult; D000782:Aneuploidy; D010064:Embryo Implantation; D004622:Embryo, Mammalian / Q000166:cytology; D005260:Female; D005820:Genetic Testing / Q000379:methods*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D008423:Maternal Age; D009693:Nucleic Acid Hybridization; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods*; D016896:Treatment Outcome