title: Karyomapping identifies second polar body DNA persisting to the blastocyst stage: implications for embryo biopsy.
abstract: Blastocyst biopsy is now widely used for both preimplantation genetic screening (PGS) and preimplantation genetic diagnosis (PGD). Although this approach yields good results, variable embryo quality and rates of development remain a challenge. Here, a case is reported in which a blastocyst was biopsied for PGS by array comparative genomic hybridization on day 6 after insemination, having hatched completely. In addition to a small trophectoderm sample, excluded cell fragments from the subzonal space from this embryo were also sampled. Unexpectedly, the array comparative genomic hybridization results from the fragments and trophectoderm sample were non-concordant: 47,XX,+19 and 46,XY, respectively. DNA fingerprinting by short tandem repeat and amelogenin analysis confirmed the sex chromosome difference but seemed to show that the two samples were related but non-identical. Genome-wide single nucleotide polymorphism genotyping and karyomapping identified that the origin of the DNA amplified from the fragments was that of the second polar body corresponding to the oocyte from which the biopsied embryo developed. The fact that polar body DNA can persist to the blastocyst stage provides evidence that excluded cell fragments should not be used for diagnostic purposes and should be avoided when performing embryo biopsies as there is a risk of diagnostic errors.
authors.affiliation: The Bridge Centre, London SE1 9RY, UK; School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK. Electronic address: cottolini@thebridgecentre.co.uk.
authors.forename: Christian S
authors.initials: CS
authors.lastname: Ottolini
authors.affiliation: The Bridge Centre, London SE1 9RY, UK.
authors.forename: Shaun
authors.initials: S
authors.lastname: Rogers
authors.affiliation: The Bridge Centre, London SE1 9RY, UK.
authors.forename: Karen
authors.initials: K
authors.lastname: Sage
authors.affiliation: The Bridge Centre, London SE1 9RY, UK; School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Summers
authors.affiliation: G.E.N.E.R.A., Centers for Reproductive Medicine, Marostica, Umbertide, Rome, Italy; GENETYX, Molecular Genetics Laboratory, Marostica, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Capalbo
authors.affiliation: School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK.
authors.forename: Darren K
authors.initials: DK
authors.lastname: Griffin
authors.affiliation: Reprogenetics UK, Institute of Reproductive Sciences, Oxford Business Park North, Oxford OX4 2HW, UK.
authors.forename: Jonas
authors.initials: J
authors.lastname: Sarasa
authors.affiliation: Reprogenetics UK, Institute of Reproductive Sciences, Oxford Business Park North, Oxford OX4 2HW, UK; Nuffied Department of Obstetrics and Gynaecology, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK.
authors.forename: Dagan
authors.initials: D
authors.lastname: Wells
authors.affiliation: The Bridge Centre, London SE1 9RY, UK; School of Biosciences, University of Kent, Canterbury CT2 7NJ, UK; Illumina, Capital Park CPC4, Fulbourn, Cambridge CB21 5XE, UK; Institute of Integrative and Comparative Biology, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Alan H
authors.initials: AH
authors.lastname: Handyside
mesh_terms: D000328:Adult; D001706:Biopsy; D001755:Blastocyst / Q000378:metabolism* / Q000473:pathology; D002970:Cleavage Stage, Ovum / Q000378:metabolism / Q000473:pathology; D055028:Comparative Genomic Hybridization / Q000379:methods; D004247:DNA / Q000378:metabolism; D004622:Embryo, Mammalian; D005260:Female; D006801:Humans; D007621:Karyotyping / Q000379:methods*; D008297:Male; D059705:Polar Bodies / Q000378:metabolism* / Q000473:pathology; D011247:Pregnancy; D019836:Preimplantation Diagnosis / Q000379:methods*
chemical_list: D004247:DNA
keywords: Karyomapping; PGD; PGS; aneuploidy; blastocyst biopsy; polar body