title: Monozygotic twins with discordant karyotypes following preimplantation genetic screening and single embryo transfer: case report.
abstract: OBJECTIVE
  to report a case of monozygotic monochorial diamniotic twins with discordant karyotypes.
  
  
  RESULTS
  the pregnancy was achieved following a treatment cycle with intracytoplasmic sperm injection (ICSI) and preimplantation genetic screening (PGS) for chromosomes X, Y, 13, 16, 18, 21, 22. One embryo euploid for studied chromosomes was transferred. Prenatal ultrasonography revealed monozygotic twins. One fetus had growth retardation, multiple organ abnormalities and polyhydramnion. The other twin had normal ultrasound appearance. Delivery on week 29 of gestation resulted in the birth of two females, a stillborn twin with karyotype 45,XX,-13[12]/46,XX,r(13)[3] and a healthy twin with normal karyotype.
  
  
  CONCLUSIONS
  the discordance in the twins' karyotypes originated from a mosaic embryo. Structural chromosomal abnormality of the affected twin could not be revealed using standard PGS investigation. Embryo splitting occurred probably due to apoptotic process in an early stage of embryo development. Apoptosis represents one of the possible mechanisms which can explain the embryo twinning process globally.
authors.affiliation: REPROMEDA s.r.o., Brno, Czech Republic. gtauwinklova@repromeda.cz
authors.forename: Gabriela
authors.initials: G
authors.lastname: Tauwinklova
authors.forename: Renata
authors.initials: R
authors.lastname: Gaillyova
authors.forename: Pavel
authors.initials: P
authors.lastname: Travnik
authors.forename: Eva
authors.initials: E
authors.lastname: Oracova
authors.forename: Katerina
authors.initials: K
authors.lastname: Vesela
authors.forename: Lenka
authors.initials: L
authors.lastname: Hromadova
authors.forename: Jan
authors.initials: J
authors.lastname: Vesely
authors.forename: Petra
authors.initials: P
authors.lastname: Musilova
authors.forename: Jiri
authors.initials: J
authors.lastname: Rubes
authors.forename: Jitka
authors.initials: J
authors.lastname: Kadlecova
authors.forename: Iva
authors.initials: I
authors.lastname: Slamova
authors.forename: Eva
authors.initials: E
authors.lastname: Makaturova
authors.forename: Vladimira
authors.initials: V
authors.lastname: Vranova
mesh_terms: D000328:Adult; D002869:Chromosome Aberrations; D002882:Chromosomes, Human, Pair 13; D005260:Female; D006801:Humans; D009030:Mosaicism; D011247:Pregnancy; D019836:Preimplantation Diagnosis; D056826:Single Embryo Transfer; D020554:Sperm Injections, Intracytoplasmic; D014430:Twins, Monozygotic / Q000235:genetics*